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Rheological studies on the interaction of xanthan and locust bean gum in aqueous dispersions Gatchair, Sonia Denise 1985

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RHEOLOGICAL STUDIES ON THE INTERACTION OF XANTHAN AND LOCUST BEAN GUM IN AQUEOUS DISPERSIONS  by SONIA DENISE GATCHAIR B.Sc,  Special,  University  of the West I n d i e s ,  A THESIS SUBMITTED IN PARTIAL FULFILLMENT  1979  OF  THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Food S c i e n c e )  We accept t h i s t h e s i s as conforming to the r e q u i r e d s t a n d a r d  THE UNIVERSITY OF BRITISH COLUMBIA M a r c h , 1985  © Sonia G a t c h a i r , 1985  2 1  In p r e s e n t i n g  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of  requirements f o r an advanced degree at the  the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and  study.  I further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may  be  department or by h i s or her  granted by  the head of  representatives.  my  It i s  understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be  allowed without my  permission.  Department of  pnnn RHTT'NTH'R  The U n i v e r s i t y of B r i t i s h 1956 Main Mall Vancouver, Canada V6T 1Y3 Date  DE-6  (3/81)  WioL  SLffj  Columbia  iqge,  written  -  ii  -  ABSTRACT  Aqueous tion,  show  dispersions  a  synergistic  concentrations, true  firm  g e l s when  phenomenon provide  some  properties  still  the  Moisture, as  the  from  the  capable  to  a s h and  of  the  two  properties  experiment.  More at  two  Solvent properties  of  conditions responsible system.  dipole  urea  were  bean  stabilizing  Hydrogen  bonding  the  and  a  solvent  hydrophobic  out  on  to  were  effect  of  ratio  steady  fractional  At  xanthan-1ocust  well  prepared  pH,  on  of  shear  factorial  the  effects  of  strength.  affected  appeared  as  treatments  The  strength,  ionic  gum s o l u t i o n s .  interactions  Rheological  content  bonds.  carried and  can  investigated.  concentration in  this  studies  dispersions  four  ionic  evaluated  in  polysaccharides  of  in  high forms  resulting  protein  properties  significantly  for  and  combina-  component  interaction.  individual  concentration  xanthan-1ocust  neither  and T h e o l o g i c a l  the  temperature,  in  sufficiently  processes  evaluated  studies  l e v e l s of  of  gum,  At  although  intermolecular  were  treatments  used,  the  and  detailed  viscosity.  elements  b l e n d were  gums  rheological  temperature  of  concentration,  bean  b l e n d were t h e r e f o r e  inorganic  weak  locust  understood  viscoelastic  disrupting  and  molecular  mechanism  viscosity  polysaccharide of  actual  the  Dynamic  polysaccharide mixing  The  in  formed,  polysaccharide  intrinsic  determined.  are  incompletely  clues  of  xanthan  increase  gels  alone.  are  of  the 20°C  be  the  bean  interactions  viscoelastic and  under  primary  gum  the force  interacting  seemed  to  play  less  important  increased solution  roles.  temperature, behavior  liquid.  interactions  may  dimensional  gel  strength comparable reflected the  two  the to  the  conditions  interactions  of were  low  ionic  lost  and  strength  polysaccharide  that  of  a viscoelastic solid  and  at  high  60°C  important  in  ionic  the  and  to  strengths,  that  of  a  hydrophobic  stabilization  of  the  three  viscosity  xanthan-locust  network. effects  solutions of  At  become  Temperature gum  the  passed from  viscoelastic  bean  Under  the  were  on  dependent  system.  In  reported  weakness  polysaccharides.  of  steady  the  shear on  the  general, behavior  concentration  steady of  interaction  of  flow  xanthan (dipole  and  ionic  properties solutions  interactions)  and  were so  between  -  iv  -  TABLE OF CONTENTS Page ABSTRACT  1i  LIST  OF TABLES  vi  LIST  OF FIGURES  vii  ACKNOWLEDGEMENTS  ix  INTRODUCTION  1  LITERATURE REVIEW  3  A.  General  3  B.  Molecular Structure Polysaccharides  C.  Xanthan-Locust  D.  Rheological  E.  Solvent  and C o n f o r m a t i o n  of t h e 5  Bean Gum I n t e r a c t i o n  Studies  13  Treatments  16  MATERIALS AND METHODS A.  B.  Chemical  9  18  Composition  and P h y s i c a l  Properties  18  1.  Moisture  18  2. 3. 4. 5.  A s h and I n o r g a n i c Components Nitrogen Content Intrinsic Viscosity D e t e r m i n a t i o n o f pH  18 19 20 22  Rheological 1.  2.  22  Sample P r e p a r a t i o n . . . . . . . . . . . . .  22  a)  V i s c o e l a s t i c Studies  22  b)  Steady  23  Rheological a) b)  3.  Studies  Shear  Flow S t u d i e s  Measurements  25  Viscoelastic Properties Steady Shear Flow P r o p e r t i e s  25 27  Statistical Analysis  29  a) b)  29 30  E v a l u a t i o n of V i s c o e l a s t i c P r o p e r t i e s Steady Shear S t u d i e s  -  v -  Page RESULTS AND DISCUSSION A.  B.  31  C o m p o s i t i o n of M a t e r i a l s  31  1.  Moisture  31  2. 3. 4. 5.  Ash and I n o r g a n i c Components Nitrogen Content Other Components. Intrinsic Viscosity  31 35 35 36  Rheological Studies  42  1.  P r o p e r t i e s of t h e P o l y s a c c h a r i d e s . . . .  42  Xanthan L o c u s t Bean Gum X a n t h a n - L o c u s t Bean Gum S o l u t i o n s F r e q u e n c y E f f e c t s on E n t a n g l e m e n t s and Cross-Linkages E f f e c t o f S o l v e n t T r e a t m e n t and T e m p e r a t u r e . . .  42 45 46  i) ii) iii) iv)  49 54 57 59  Viscoelastic a) b) c) d) e)  f)  Limitations i) ii) iii) iv)  2.  Steady a) b)  E f f e c t of Urea E f f e c t o f Added E l e c t r o l y t e s E f f e c t of A l k a l i Temperature E f f e c t s  69  F a i l u r e t o Meet Some A s s u m p t i o n s i n V i s c o e l a s t i c Theory E f f e c t o f Added S o l u t e s C h o i c e of Frequency Nature of t h e C r o s s l i n k a g e s  Shear Flow  48 49  Properties  General C o n s i d e r a t i o n s F l o w P r o p e r t i e s Under D i f f e r e n t  69 71 72 74 76  Conditions....  76 79  CONCLUSIONS  90  REFERENCES  92  APPENDICES  98  -  vi  -  LIST OF TABLES Page  Table  Table Table Table Table  1.  2.  3. 4.  5.  T r e a t m e n t c o m b i n a t i o n s f o r x a n t h a n - 1 o c u s t bean gum s o l u t i o n s f o r t h e f r a c t i o n a l f a c t o r i a l e x p e r i m e n t a c c o r d i n g t o t h e scheme o f Taguchi L27 (313)  24  Summary o f v a r i a b l e s and l e v e l s u s e d i n T a g u c h i ' s F r a c t i o n a l F a c t o r i a l Experiment  28  Summary xanthan  32  of n o n - c a r b o h y d r a t e c o m p o n e n t s and l o c u s t bean gum p o w d e r s  I n t r i n s i c v i s c o s i t y and pH f o r l o c u s t bean gum s o l u t i o n s  xanthan  for  and  Summary o f f l o w p a r a m e t e r s ( Y = 0 . 2 - 175 s"1) 1 obtained from T a g u c h i s f r a c t i o n a l f a c t o r i a l experiment  39  80  -  vii  LIST OF FIGURES Page Figure  1.  Pentasaccharide repeating  Figure  2.  Representative  s t r u c t u r e of  Figure  3.  Representation  of  interaction Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  4.  5.  6.  7.  8.  9.  10.  11.  12.  13.  14.  unit  xanthan  5  l o c u s t bean gum  xanthan-1ocust  ( f r o m Dea e t  of  bean  6  gum  a l . , 1977)  Combined H u g g i n s ' ( • ) and K r a e m e r ' s extrapolation to i n t r i n s i c v i s c o s i t y xanthan (0.1 M N a C l , 2 0 ° C )  10 (o) for 37  Combined H u g g i n s ' ( • ) and K r a e m e r ' s (O) extrapolation to i n t r i n s i c v i s c o s i t y f o r l o c u s t bean gum ( 0 . 1 M N a C l , 2 0 ° C )  38  Dynamic s t o r a g e and l o s s m o d u l i f o r x a n t h a n , l o c u s t bean gum and x a n t h a n - 1 o c u s t bean gum s o l u t i o n s (0.4% i n water at 2 0 ° C )  43  L o s s t a n g e n t f o r x a n t h a n , l o c u s t bean gum and x a n t h a n - 1 o c u s t bean gum s o l u t i o n s ( 0 . 4 % i n w a t e r a t 20 ° C ) ,  44  D y n a m i c s t o r a g e ( a ) and l o s s ( b ) m o d u l i f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r , 8 M u r e a , 0 . 6 M KC1 and 1 M K0H a t 2 0 ° C  50  D y n a m i c s t o r a g e ( a ) and l o s s ( b ) m o d u l i f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r , 8 M u r e a , 0 . 6 M K C 1 , and 1 M K0H a t 6 0 ° C  51  L o s s t a n g e n t f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r , 8 M u r e a , 0 . 6 M KC1 and 1 M K0H a t ( a ) 2 0 ° C and ( b ) 6 0 ° C  52  E f f e c t o f t e m p e r a t u r e on t h e s t o r a g e m o d u l u s x a n t h a n - l o c u s t b e a n gum s o l u t i o n s i n w a t e r  for 61  E f f e c t o f t e m p e r a t u r e on t h e l o s s m o d u l u s f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r  62  E f f e c t o f t e m p e r a t u r e on t h e l o s s t a n g e n t f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r  63  E f f e c t o f t e m p e r a t u r e on t h e s t o r a g e m o d u l u s f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n 0 . 6 M K C 1 . . .  64  vi i i  -  Page Figure  Figure  Figure  Figure  Figure  Figure  15.  16.  17.  18.  19.  20.  E f f e c t o f t e m p e r a t u r e on t h e l o s s m o d u l u s f o r x a n t h a n - 1 o c u s t bean gum s o l u t i o n s i n 0 . 6 M K C 1 . . .  65  E f f e c t o f t e m p e r a t u r e on t h e l o s s t a n g e n t f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n 0 . 6 M K C 1 . . .  66  Rheograms f o r x a n t h a n - l o c u s t a t 20°C p l o t t e d a c c o r d i n g to f l o w model  bean gum s o l u t i o n s t h e power l a w 77  E f f e c t of t e m p e r a t u r e on f l o w b e h a v i o r o f x a n t h a n - l o c u s t bean s o l u t i o n s  index 82  E f f e c t o f t e m p e r a t u r e on t h e c o n s i s t e n c y c o e f f i c i e n t o f x a n t h a n - l o c u s t bean gum solutions Effect  of  ( y = 50 s solutions  temperature _ 1  )  of  on t h e  apparent  xanthan-locust  83  viscosity  bean gum 84  -  ix  -  ACKNOWLEDGEMENTS  The Marvin  author  A.  Tung,  encouragement extended Shuryo for  to  as  the  is  also  Donald  and D r .  and  greatly  provided  the  parameters The  The  program  i s also gratefully author  also  and  Engineering  Research  for  members  appreciated.  computer  these  this  Council  studies.  his  the  to  Dr.  advice  and  Thanks of  are  Pathology  Department  of  and  also Dr.  Food S c i e n c e  thesis. Consultation of  the  the  Laboratory  Department of  Mr.  calculation  of  as  Food  well  Science  A.  Paulson,  who  of  viscoelastic  acknowledged.  wishes  Fellowship  for  work.  assistance  for  appreciation  Department  of  Statistical  from  this  the  Powrie  sincere  Science,  of  of  r e v i e w of  support  Food  Brooks  the  her  course  W i l l i a m D.  and  Scholarship  support  of  the  E.  g u i d a n c e of  help  express  Department  interest  The  to  throughout  Dr.  Nakai  their  wishes  to  acknowledge  Committee of  and  Canada  the the  for  Canadian Natural  provision  Commonwealth Sciences of  and  financial  - 1-  INTRODUCTION  Hydrophilic disperse few trap  in water  to  c o l l o i d s , also or  immobilize  Rheological  The is  have  the  ability  in  large  interactions.  classical  a  in  the  to  an  possessing  v i s c o u s and e l a s t i c  behavior. measure response  Dynamic of to  movements times.  both  These and  are  the  solid  lifetimes  information  on t h e  interacting  system.  this  nature  for  is  It  bonds  are  present  technique  Knowledge  bonds of  their of  dimensional  or  weight. these on  the  solution. matrix  described a  or  intermolecular in  Newtonian  that  is,  characterizing  non-disruptive  provides  frequencies)  of  to  A  which  information  adequately  liquid-like  properties of  networks  suitable  solid  effect.  or  terms fluid.  materials  properties.  and  (low  material  conditions,  dissolve  assessment  viscoelastic,  shear  stress.  long  rigid  provide  of  be  available  oscillatory  applied  at  strengths suitable  both  which  compared  a three  elastic  termed  techniques  can  form  cannot  they  Several  firm,  objective  development  of  are  form  an  Rheologically, both  polymers  these macromolecules in  materials  models  to  addition,  colloid  on  These  chain  proportions  provide  and  of  long  ability  and d i m e n s i o n s o f  dependent  the  are  a t h i c k e n i n g or v i s c o s i t y producing  water  properties  conformations  gel  give  measurements  functional  of  colloids  or  the  has  components  short  inherently in  the  the  forces forces  and  provides of  information  and  viscoelastic  on  (high  involved  molecular  frequencies)  system.  involved  material  dependent  potential in  a  on  Thus, for  the under  providing  stabilizing  and t h e i r  an  relative  - 2 -  importance atoms  or  can  provide  groups  of  an u n d e r s t a n d i n g Steady rheological  and  energy  factors  the  this  in  shear  of  in  of  interaction,  at  the  factors,  be  during  the  reported  between  contributing  or  in  to  characterizing  disruption rates,  used  in  stirring  as w e l l  useful  these in  as  Rheological material  operations of  weak  provides  predicting  processing  determination  of  it  properties.  therefore  such  as  properties  the  practical  system.  gum  The  properties this  system  in  shear  In  rheological  conditions  of  determined.  solvents  were  addition,  properties  c h o s e n , were  change  stabilization  were  different  information.  conformational  evaluated.  responsible for  interacting  on s t e a d y  evaluated.  shear  pouring  can  are  used the  organoleptic  The  provide  were  be  low  principal forces  bean  to  in  during  of  viscoelastic  order  could  but  interaction  thereby  technique  result  rates  them,  colloidal  study,  several  rates,  effects  the  dynamic  monitored,  can  filling.  xanthan-locust  Changes  effect  or  actual  gelation.  It  requirements  affecting of  of  another  shear  the  macromolecules,  behavior  higher  on  is  assessment  pumping  application  of  flow  interactions,  at  and  In  mechanism  on m a t e r i a l  properties,  extrusion,  the  shear  objective  behavior  on t h e  behavior.  information the  atoms  of  inter-molecular  for  information  the  at  low  such t h a t  the  xanthan  on  the  - 3 -  LITERATURE REVIEW  A.  General Hydrophilic  describe  colloids,  materials  produce  widely  suitable  products.  In  properties, coatings,  they  are  their  quantities colloids with  in  food  starch,  was  from  u s e d gums o r  gelatin,  these  chemical  structures,  but  in the  ides  ring  having  t y p e of  sugar  a  million  in  various  and  gelling  protective  in  world  pounds  1982). and,  only use  small  of  hydro-  (Glicksman,  comprising  the  are  not  nature  only  in the  orientation  (Aspinall,  1982).  unbranched  and  heterotypic  different  types  of  sugar  the  polymer  in nature.  inherently of  1982)  bulk  of  The  component  types  molecules  structures,  functional  formed  e.g.,  may  on  sugar  include  polysaccharides These  commonly  dependent  homopolysaccharides  units.  all  g l y c o s i d i c bonds  Structural  branched  starch;  linear,  of  with  of  hydrocol1oid,  polysaccharide  homopolysaccharides  more  to  additives  used  estimated  polysaccharides  relative  straight,  are  i.e.,  or  industries  as  food  are  proteinaceous  unit,  component  to  (Glicksman,  as  cellulose derivatives  hydrocolloids  of  each sugar  the  used  suspending  functions  role,  500  other  stabilizers,  considered  1979,  terms  used.  Apart  also  other  under  and  and  are  characteristics  emulsion  functional  just  food  gums  thickening,  of  in  or  textural  generally  Thus  gelatin  the material  properties  foods.  as  a host  important  in  the  their  used  are  in  and  to  as f o r  Hydrocolloids despite  used  structural  addition  as w e l l  hydrocolloids  to  their  residues and  from  polysaccharfrom  a  single  such as  cellulose;  the  amylopectin  which be  contain  arranged  two in  a  -  relatively  s i m p l e manner  agarose. not In  The r e p e a t i n g  be g e n e r a t e d alginates,  may a r i s e  forms  together  secondary  structure  t o form  structure members  Secondary  favorable  energy  bonding,  in  random locust  unlike  the  as i n o r may  et a l . 1982). sequences  bean  state  favorable  gum ( M o r r i s chains  structure  this  ribbon  family  form  from  and  residues  of  can lead  such  solvent  about  secondary  persist  in  al.  1982).  or  double  as  by a  hydrogen  effects.  regular  The  sequences  stabilization (Rees,  structures solution.  interactions  to the development  in solution, et  single  the polysaccharide  The o r d e r e d , may  et  likely  are s t a b i l i z e d  on l o n g ,  to bring  and W e l s h ,  t h e most  interactions  interactions  arrangements  (Rees  (Rees  in polysaccharides  but  these  polysaccharide,  an e x t e n d e d  d e f i n e s any  s e q u e n c e may a d o p t ;  organization  solvent-polymer  conformation  polysaccharide  linked  entropy  of t h e molecule  coil  of  are required  1977).  in the polysaccha-  t h e way i n w h i c h  level  between  chain  solid  i n space t h a t  resulting  ionic  interaction  more  flexibility  and  (Rees,  as h e t e r o t y p i c  secondary  carrageenan  structures  and W e l s h ,  instances,  or  of  the conformational  Rees  favored  a g-1+4  the  and  polysaccharide  1977;  a higher  balance  dipolar  co-operative  outweigh  as w e l l  structure;  defines  i s that  of  helices.  the  unit,  as i n A - c a r r a g e e n a n ,  bound monomer u n i t s  arrangement  For c e l l u l o s e ,  Various  sequences  the primary  regular  the t e r t i a r y  1977).  repeating  at a l l , e . g . , t h e galactomannans  sequence of c o v a l e n t l y  chain  pack  obvious  may be m a s k e d ,  homopolymeric  geometrically and  unit  a fairly  i n t h e same m o l e c u l e .  The ride  to give  4 -  and 1972;  a r e more In  and t h e  of a d i s o r d e r e d  The i n t e r a c t i o n  i n s o l u t i o n may l e a d  some  natural  e . g . , the galactomannans,  a l . 1981).  of  guar  o f l i k e and  t o t h e development  of  - 5 -  tertiary which  structures  give  r i s e to  Chemical functional  B.  modification  alginate)  This  functional  results  in  derivatization  such  as  water  or  acid  (Glicksman,  solution  c h a r a c t e r i s t i c s of  and  cellulose)  polysaccharides. serve  solubility  resistance  properties  to  improve  (cellulose  (alginate  to  to  propylene  1982).  Molecular Structure and Conformation of the Polysaccharides Xanthan  microorganism  gum  residues,  as  with in  mannose-glucuronic give  the  is  the  extracellular  Xanthomonas  polysaccharide  to  the  solution.  properties  carboxymethyl glycol  in  a  campestris.  backbone  cellulose,  but  acid-mannose  pentasaccharide  polysaccharide It  is  consisting having residues  repeating  > 4)-g-D-Glcp-(l  unit  a  of  glucose  on  glucose  other  in  Figure  1.  + 4 ) - 3 - D - G l c p - ( l -»• 3 + 1 a-D-Manp-6-0Ac 2 + 1 3-D-GlcAp 4 + 1 3-D-Manp  6  C"H7  Pentasaccharide  linked side  shown  repeating  ^COOH  unit  of  the  acidic  trisaccharide every  by  branched,  g-1+4  4 ^  Figure 1.  produced  xanthan.  chains  of  residue  -  Mannose with  acetate  residue  residues  residues  may  be  closest  6 -  to  the  main  (6-0-acetyl-D-mannose)  substituted  with  chain while  pyruvate  to  (4,6-(l'-carboxyethylidene)-D-mannose)  (Jansson  al.  and  1976).  according of  the  The to  (Sandford  cooperatively  with  Locust  rise  et  D-glucose,  branched  strain, to  differences Smith  et  D-mannose  bean  gum  The mannose  galactosyl  units  or D-xylose  (from  the  with  a  backbone  (McCleary  et  give  et  a  al.  conditions  unbranched  legume,  backbone  (Morris  3-1+4  and  F i g u r e 2.  of  3-1+4  et a l . 1977). siliqua)  linked  is  a  D-mannose  at 0-6 w i t h  A representative  structure  of  gum b i n d s  structure  a-D-Gal p 1 + 6 4 ) - 3 - D - M a n p - ( l •»• 4 ) - 3 - D - M a n p - ( l 6 + 1 a-D-Galp  Representative  history  properties  2.  a-D-Gal p 1 + 6 4 ) - 3 - D - M a n p - (1 6 + 1 a-D-Galp  et  varies  sequences of  i s partially substituted  a l . 1984).  Melton  Xanthan  Ceratonia of  ketal  substitution  1981).  residues  mannose  sugar  1975;  i n the s o l u t i o n al.  substituted  the terminal  acetate  fermentation  polysaccharides having  polysaccharide  in Figure  pyruvate  a l . 1977;  residues.  shown  of  the bacterial  gum and g i v e s  xanthan  linked  degree  may be  l o c u s t bean gum.  a-D is  -  Locust ides of  known  bean  of g a l a c t o s e  galactomannans from  are able  xanthan,  with  proportional  to In  substituted,  with  with et  xanthan,  which  to  interact  t h e degree  LBG,  only  of  of  differ  of  polysacchar-  i n t h e degree  with  other  interaction  galactose  about  the result  agarose  of t h e f a m i l y  and p a t t e r n  r e s i d u e s a l o n g t h e mannose m a i n c h a i n .  t h e degree  backbone.  -  gum (LBG) i s a member  as t h e galactomannans  substitution  7  that  being  the  roughly  at  on  D-mannosyl  3-dimensional  and c a r r a g e e n a n  polysaccharides  substitution  30% o f  The  inversely  the  mannose  residues  gel complexes  suitable  apart  are  can form  concentrations  (Dea  a l . 1972). The  molecular  properties native  low  have g e n e r a t e d  state,  persists  strength  intramolecular  handed  1977)  helix.  conformation, to  covalent  at  exist  a  1976;  ambient  to  et  Under  1977).  et  the ordered  al.  (1977)  structure  of  suggest down  form  in  ( H o l z w a r t h and is a the  and a l i g n e d w i t h  stabilized  by  (Rees,  diffraction  xanthan  that  of  u n d e r g o e s an  X-ray  form  which  conditions  disordered  and e l e c t r o n m i c r o s c o p i c e v i d e n c e that  In t h e  conformation  the molecule  a more  al.  solution  i n recent y e a r s .  temperatures.  change  Morris  suggest  rigid  and c o n s e q u e n t  i n an o r d e r e d  the side chains are folded  right  ordered t h e main  intra-molecular  non-  bonding. et  transition  agreement  xanthan  and i n c r e a s e d t e m p e r a t u r e ,  Morris  give  Norton order  molecules  e t a l . 1977)  Prestridge,  of  considerable interest  conformational  Holzwarth,  (Moorhouse  chain  xanthan  on d i s s o l u t i o n  ionic  1972;  conformation  with  a l . (1980) using  monitored  stopped  flow  a r e a c t i o n of t h e form  the salt  polarimetry.  (K+)  induced  Results  were  disorderin  good  -  8  Coil  where the f i r s t - o r d e r  -»• H e l i x  0  the  [1]  r a t e equation f o r the process i s given by  £n[a /(a  In  -  equation,  a  0  is  0  - x)] = ^ t  the  [2]  total  pentasaccharide  (based on a mean repeat u n i t of 1000  concentration  x i s the r e s i d u e c o n c e n t r a t i o n i n the h e l i x form The as  the  scattering stranded (1978) or  of  (Norton  a  and  length  between  6000  of  xanthan of  at time t .  properties.  model  Norton  coil  to  could was  et  helical  an o v e r a l l  broken-rod  1978;  Holzwarth  more  a l . (1984),  single-helix  disordered  electron  10,000A.  also  be  state  transition,  is a  single  and  Holzwarth  evidence  and  Whitcomb  and  et  a rigid, Based  (1981)  interpreted  after  light  microscopic  Jamieson  consistent  by  two  ( M o r r i s , 1977;  as  as well  i s m u l t i s t r a n d e d with  on  analysis  a l . 1982) rodlike the  have  molecule  hydrodynamic  p o i n t e d out t h a t  the  as a wormlike c h a i n ,  with  the of  concluded  sequences c o - e x i s t e d w i t h i n the structure.  monitored  ordered  state  in solution and  as  process  Prestridge (1977)  workers  Milas,  in solution,  xanthan  this  on  the  and  ordered  Other  exists  that  the  Rinaudo  weight  suggest  based  xanthan  conformation  for  strands  the  that  behavior  and  that  properties.  1978;  suggested  molecular  However, Holzwarth  three  hydrodynamic  in  a l . 1984)  et  have suggested  perhaps  with  increase  helix.  Macosko,  molecular weight) and  c o n c e n t r a t i o n independence of the t r a n s i t i o n  lack  residue  hydrodynamic  equilibrium that  data  ordered  same molecule  and  giving  -  The  conformational  interest.  Based  various et  al.  (1972)  extended coil  properties  on c o m p u t e r  researchers  on  conformation  model  related  suggested  ribbonlike  9 -  that  of  locust  in solution.  bean  of  xanthan  association  of  the  (Figure  3).  Locust  interaction  with  association  of  bean  xanthan.  Gel  unsubstituted regular  residues  unassociated  network  by  molecular leading cohesive  precipitation  to  occurs  in  Both  the  and  for gelation,  and t o o l i t t l e  with  preventing  a random  rigid,  but  Dea  and  gum  involves  bean  lightly  as  Morris a  substituted of  xanthan  conformation  a  result  containing  and  of  t o form  solubilization  associating  2-fold,  linkages.  of t h e galactomannan Regions  of  and Dea  and a d o p t e d  i t s ribbon-like  formation  and h e l p  are essential  or  work  a  t h e c e l l u l o s e - l i k e backbone  zones.  hydration.  locust  unsubstituted  regions  junction  (1973),  such  on the  long,  galactose of  the gel  non-associating  t o o much  association  the formation  of  a  network.  The has  extensive regions  to  with  with  gum r e v e r t s  structurally are  Morris  interaction  o f t h e LBG m o l e c u l e  in  about t h e g l y c o s i d i c  (1972),  regions  existed  i s not t o t a l l y  Xanthan-Locust Bean Gum I n t e r a c t i o n  co-operative  (1972)  The m o l e c u l e  restricted mobility  the  Rees  state  C.  (1977),  gum  no  and t h e  i n the solid  severely  Rees  generated  studies  polysaccharides,  conformation  to  have  building  has  According  LBG  number o f  n o t been  sugar  determined  mannan  oligosaccharides,  length  for stable  residues  as y e t . Rees  et  involved  Based al.  zone  formation  on t h e s o l u b i l i t i e s o f g a l a c t o -  (1982)  a s s o c i a t i o n of at l e a s t  in junction  suggested  10-15  a critical  residues.  chain  -  10  Mixed  can f i t to  ionic  the  linear  galactose the  The galactose  to  linked form  linear  ordered,  1972;  solubility  the  polysaccharide  of  is  mannans,  galactose  are  of  xanthan  substituents  on  the  with  mannan  structure  which are  difficult  or the  Thus  whereas  interaction  uniform  inter-molecular  soluble with  substituents  galactose  gum  Branching  insoluble,  of  of  1973).  polysaccharide.  interaction  arrangement  polysaccharides  p o s s i b i l i t y of of  bean  c r y s t a l l i n e arrays  Whistler,  reduces the  substituted  proportion  likely  1+3  (Rees,  charges  increases linked  or  together  separate  gel  R e p r e s e n t a t i o n of x a n t h a n - l o c u s t (Dea e t a l . 1977).  F i g u r e 3.  g-1+4  -  the  presence  association mannan,  a  of and  g-1+4  galactomannans,  solubility  i n c r e a s i n g as  increase. galactomannans  main  chain  substituents  decrease  increases.  which  as  the  The  most  facilitates  this  -  interaction block-like Baker  i s one i n w h i c h t h e manner  and W h i s t l e r  consisted  of  substituted residues. Dizet,  and  than  locust  bean of  action in  a  the  gum  al.  the  et  al.  a l t e r the  by  (1982)  would other  of  the  could leave  all  with  that  al.  of  the  interactions  interaction.  came t o  Since  the  that  However,  this  picture  in the  galactomannan  unsubstituted McCleary  out  that  side  of  locust  quite  different  the  model.  bean  most  mannose  regions for  proposed  between  in  gum  of main  inter-  However, molecules,  c o n c l u s i o n s on  crystalline  or  (1979),  sequences  the  unsubstituted  mannan  irregular  concluded  alternating  same  the  an  propor-  1984).  on  building,  high  regions  chain,  et  of  (McCleary,  l a r g e a r e a s of  (1979),  diffraction  al.  presence  pointed  conclu-  McCleary  in  are those  (1982)  Le  were  McCleary  triplets.  and  substituents  arranged  xanthan  mannan be  similar  manner.  the  average,  unsubstituted  X-ray  galactose  were  by  not  studies,  Courtois  to  using  random  molecules according to  consideration et  of  came  studies,  theory  Painter  (e.g.  in a  contiguous  s t u d i e s and c o m p u t e r model  D-galactose  and  a  his  but  contiguous  also  that  typified  "junction-zones"  residues  with  was  twenty-five  (1979),  residues  couplets  conformation  This  degradation  structure  substituted  in  From  degradation  other workers  concluded  manner.  were  studies, et  are arranged  l o c u s t bean gum, on an  eighty-five  that  galactose  c o n s i d e r e d to  Marchessault, nature  (1982),  substituted  galactose chain.  noted  chemical  there  and  Marchessault  random  form  lightly  which  enzymatic  Painter  that  rather  stable  using  From  concluded that  residues  using enzymatic  concluded  was n o t  1982).  in  (1982)  -  galactose substituents  on t h e mannan m a i n c h a i n  (1984),  Rees  mannose  However,  arranged  which  regions  1970),  studies  (1975)  Painter  sions.  tions  (Painter,  11  structure  the was  -  absent  in  workers  stretched  and d r i e d  considered  it  crystalline  regions  saccharide.  They  unlikely  organized  concluded  -  films  of  locust  that  the  bean  hydrated  g u m , he  gels  that  directly  with  the  possible  that  interaction  the D-galactose  D-mannose of  xanthan  of  with  contain  i n mannan  residues  residues  and c o -  would  i n t h e same way a s t h o s e  interact  the  12  on one c h a i n  another.  locust  poly-  bean  It  is  gum c o u l d  o c c u r by s u c h a m e c h a n i s m . The not  been  determined  junction when  zone  the  similar by  stoichiometry  stoichiometry  ranging  isolated greater  gel  higher  residue or  proportion.  Morris  and  (1973)  intramolecular  interaction  1980). of  the  locust  greatest  observations  attributed  interaction  a c t between  (Richards,  when of  equal  and  when  occurred  proportions. model  removed  A  presented  soluble  locust  a  bean  polygum i n  of p o l y s a c c h a r i d e i n the  proportion bean  gum.  locust  suggested  bean that  of  xanthan  Soluble  was poly-  gum was i n t h e a 1:1  stoichio-  likely.  non-covalent  which  These  were  xanthan  suggested  gel strengths  (1979)  Concentrations  that  (1973)  in the molecular  of  highest  to  concentrations  m e t r y was q u i t e  to  equal  nearly  McCleary  mixtures  were  in  assumed  5:1 to 1 : 5 .  Kovacs  s i n c e maximum  were  (1977).  t h e two p o l y s a c c h a r i d e s has  However,  1:1  i s also  gelling  from  than  saccharide  of  polysaccharides  from  between  conclusively.  Dea and c o - w o r k e r s  ratios  binding  stoichiometry  two  saccharide  of  molecules  the binding  forces.  and c h e m i c a l are  These  forces  arise  polar  groups  or  t h e two p o l y s a c c h a r i d e s  Secondary,  interactions  charged  of  groups  primarily in  non-covalent rise  to  inter-  electrostatic  in  nature  several  (multipole  giving  forces  ways  and i n c l u d e t h e  interactions  and Van  -  der  Waals  exclusion  forces), forces.  Unlike  interactions  arise  system r a t h e r  than  Rees for  from  which  are  little  relevance.  s t a b i l i t y of  important The the  the  presence  same d e g r e e a  for  small  by  that  (1982)  showed  of  t h e weakness of  gel,  of  the  the  xanthan  ionic  (monopole)  charge t r a n s f e r  inter-  nucleic acids probably  the  are  (0.1%  have  w/v)  was  is  (0.1%  w/v)  in  to  the  hydrolyzed  bean  at  that  i n t e r a c t i o n between  gum  He c o n c l u d e d t h a t  locust gum  co-operatively.  bean  B-D-mannanase.  xanthan  individually  act  locust  unsubstituted  measurements  interaction information  of on  xanthan gel  strengths gel  were  strengths  have with  of  measured were  been  the  the the  gum  only  molecule  "junction  observed  was  zones".  results  are  two p o l y s a c c h a r i d e s .  used  and  with  to  demon-  Kovacs  (1973)  'elasticity'  gum r a t i o ,  obtained  extensively  galactomannans.  strengths  bean gum g e l s a s a f u n c t i o n  maximum  interactions  Studies  "Rheological"  Gel  and  that  interpretation  pH.  and  and  i s , when t h e y  alternative  and  the  them  an  locust  in  s y s t e m i s a c h i e v e d o n l y when a l a r g e number o f  However,  presented  place  relevant  dipole  interactions  with  the  most  hydrophobic  interaction  strate  taking  hydrophobic  weak  an e n d o - h y d r o l a s e ,  Rheological  the  bonding,  in  D.  processes  that  involved  due t o  interactions,  and  so  absence  proportion  other  proteins  secondary  al.  and  the  interactions  attractions.  from  simultaneously favorable, McCleary et  hydrophobic  related  hydrogen  Contributions  actions  of  suggested  p o l y s a c c h a r i d e s were  that  most  entropy  1972)  -  bonding,  by C o u l o m b i c  (1969;  interactions.  are  hydrogen  13  total  of  xanthan-  gum c o n c e n t r a t i o n  a Bloom G e l o m e t e r .  For  with  bean  xanthanrlocust  a  1% gum  -  ratios  in  the  increasing obtained being  range  in  the  produced  a  by bean  contained  obtained  with  bean  using  Consistency  and  acid  a  the  the  Gel  solutions  at  with  of  with  strengths  were  in  gel  the  was  9:1  and  the  two  different  Model  LVT  increasing  gum  when  The  gums. gum  spectrum.  relationship  greatest 1:9.  strength  pH  force-deformation  of of  decline  sides  Tester,  ratio  Brookfield  rapid  gel  increased  xanthan-  least  elastic  Consistency  of  concentrations  were  Viscometer  (60  r.p.m.).  concentration  and  decreased  temperature.  locust  bean  Instron cell  et  and  using  (yield of  the  a  speeds  between  Model  of  10  1122  mm/min.  The  presence  of  guar  Dea  of et  and  this  network al.  in  similar  blends.  viscosity  using coaxial  to  were  a  of  20  N  primarily  gum  on  resulted  competitive  used o s c i l l a t o r y t e c h n i q u e s  the  results  Morris of  attributed  with  guar gum  plates  gel in  a  inhibi-  structure.  (1977)  enhancement  was  xanthan-  parallel  They  stresses). stress  of  equipped  added  gum  were o b t a i n e d  Tester  strengths  of  locust  of  samples  gel  effects  blends,  enhancement  crosshead  the  the  xanthan-guar bean  compressing  Materials  formation  marked  determined  demonstrating  yield  Although rate  by  Universal  strengths  of  (1980b)  gels  with  lowering  al.  gum  concerned  tion  alkaline from  strengths  Maximum a  proportions  gum  increased  Morris  load  in  equal  Gel  8 with  Colloids  were  4:6.  6 to  determined  gum  xanthan-locust  pH  the  Marine  and  -  concentration.  of  both  as  an  range  at  Elasticity,  gels  6:4  polysaccharide  noted  locust  of  14  et  dynamic  rigidity  have n o t  been  al.  xanthan-guar  (1980b) blends.  cylinder fixtures  and  demonst-  viscosity  presented also  to  for  xanthan-  demonstrated  Viscosity  with a shear  of  the  measurements  rate  of  10  s"1.  -  McCleary cartridge  at  (1979)  80  used  r.p.m.  a  and  investigate  the  of  xanthan  and  galactomannans  viscosities  were  highest  proportions  and  xanthan  effects  lowest  was  observed  with  amylograph  in Brookfield  in  ratio.  a 1:2  Consistency to  gum.  techniques  Gelometer, information. inadequate  of  instrument  different  the  proportion  A  used,  of  gel  interaction  bean  different  workers,  as  bean  gum  solutions  to  showing viscosity  An optimum was were  been  used  of  with  locust  bean  xanthan  Colloids do  behavior  not  of  comparison  these  i n equal  have  measurements  little  interaction  gum and x a n t h a n  viscosity  very  to  i n amylograph  point  result,  r.p.m.  strengths  Marine  flow  cmg  Amylograph  locust  Single  characterizing  350  gum w e r e  3-mannanase.  locust  and  e.g.,  bean  drop  t h e enzyme,  c o n s i s t e n c y when  the  gelling  polysaccharide rapid  a  proportions.  and l o c u s t  individual  viscosities.  on t h e  and  are  Gel  Tester,  provide are  fundamental also  these  Bloom  totally  non-Newtonian  c a n be made  with  the  valid  the  same  only  where  and t e s t i n g c o n d i t i o n s a r e u s e d . (1976;  1980)  food  carrageenan,  gelatin,  considered.  In  and  the  treatment  empirical  macromol e c u l a r  creep  a t . 20  mostly  As a  Mitchell by  viscometer  been  for  dispersions. results  as  demonstrate  have  Brookfield  measurements  extensively The  with  xanthan  i n the presence of  observed  Amylograph  in  when  -  Brabendor  enzymic  decreased  decreased  the  of  a  15  additives. pectin  addition  stress  reviewed  to  relaxation  and  rheological In  tests  particular  microbial  the empirical have  studies  agar,  polysaccharide  methods been  on g e l s  the  mentioned most  formed  alginate, gels  were  previously,  commonly  used  -  techniques  in  the  study  of  16  polysaccharide  h a v e been a p p l i e d t o o n l y a l i m i t e d  E.  gels.  Dynamic  shear  methods  extent.  Solvent Treatments Protein  of  -  gaining  important and  insights  the  or  valence  exception  have  such  three  general  heat,  solvents  in  terms  existing disrupt  ability of  hydrogen long  structure  of its  of  guanidinium  urea  to  to  This,  polymer-polymer  interactions  been  protein effect  attributed  in  solutions  turn,  part, when  to  in  more  in  in  the  involved  Denaturation salts,  terms  pure the  has  with  in  in  agents organic  explained  proteins  replacing  of  its  in  of  Salt  polymer-water  effects  solubility in  to  in the  polymer-solvent  the  water,  ability  Changes  nature  favorable.  with  been  water.  whether  differences  compared  change  to understand the  inorganic  directly  determines  become  form.  (1973)  i s considered  the forces  denaturant  and,  changes  these  addition  or have  of  the  to  its  on e l e c t r o s t a t i c i n t e r a c t i o n s . The  applied  salt  in  a  bind  a  hope  to t h i s end.  c h a r a c t e r i s t i c s of  leads in  to  as  interactions  interactions.  also  act  ability  linkages  of  salts,  have been e m p l o y e d  order  water  disulfide  folded  of  any c h a n g e  One a p p r o a c h t a k e n  i t s compact,  bonding  range  rule.  as  without  i s the determination  urea,  and d e t e r g e n t s  The both  pH,  in  of  the  and H a s c h e m e y e r  denaturation  structure,  with  and f u n c t i o n s  Haschemeyer  The b r e a k a g e  to t h i s  studied  properties  protein  dimensional  bonds.  the molecule  as  extensively  structure,  defined  mechanism of d e n a t u r a t i o n , holding  been  macromolecules.  (1978)  conformation  has  on t h e  biological  Lapanje  primary  denaturation  to  use of  these  dissociating  polysaccharides.  agents  Dintzis  have et  been  al.  less  (1970),  extensively based  on  -  determinations molecular  of  xanthan  solutions  of  in 4 M urea.  found  viscoelastic  that  viscoelastic to  heat  et  al.  after  solid  (1983) heat  generally hydrogen  Attempts  tions  of  of pH  et  al.  dynamic  network  associations  primarily taking to  various  water for  (to ionic  bonds)  made  ionic  molecules protein.  strength Lowering  treatment work  fish  solvent test  bonds),  (to  differences were  inter-  study  (Gibbs  levels  during  M urea test  (to for  in the  monitored  by  Southwick  and  changes  conformation effects  were  intra-molecular  in  et  al.  1968;  the  viscoelastic  Welsh  to  et  condi-  al.  strength  1980;  enhanced  increased intermolecular  used  in  (1979). frozen  The  this He  test ionic  degree of measuring  for bonds  after  treatments  hydrogen  adapted  subjected included  0.6  M KC1  (to  bonds  and  cross-linking in  being  changes  used,  and o t h e r s ) .  changes  were  studied chemical  storage  solvent  study  non-specific association forces), 8  and  These  pH and i n c r e a s i n g i o n i c  treatments.  for  subjected  i n a random c o i l  of  a  being  (1982)  solutions.  of  and m o l e c u l e s .  to  Matsumoto  protein  (1983)  electrostatic repulsions.  and of  et a l .  a g l y c o s a m i n o g l y c a n , under d i f f e r e n t  by s u p p r e s s i o n o f  in  al.  p r o p e r t i e s and w e r e a t t r i b u t e d  and 1 M KOH  Matsumoto,  disruption  have  from the  place  s a l t - f r e e 4 M urea the  et  existed  aggregates  1980a).  Solvent  Jamieson  xanthan  been  poly-  after  urea.  to  Ross-Murphy  the  liquid  i n xanthan  and  (1982),  heating  macro-  a viscoelastic  4  in  after  true  passed from t h a t  in  M  only  that  (0.5%)  hyaluronic acid,  Morris,  al.  concluded  xanthan  of  concluded that  bonding  et  formed  p r o p e r t i e s of  attributed  properties  Frangou  that  treatment  weight,  were  to  treatment  -  molecular  xanthan  saccharide  17  the  non-polar  In t h e  between  test  the  solubility  study  of  protein of  the  -  18  -  MATERIALS AND METHODS  A. Chemical Composition and Physical Properties In  order  molecular  level  materials  of  latter of  locust  gum  defined  principal  Inc.,  taking  composition  of  Merck  should  Inc.,  York,  NY)  components  and pH o f t h e s a m p l e s w e r e  at  be u s e d .  the or The  available  samples  San D i e g o ,  CA) and  were  and  also  place  pure m a t e r i a l s  Commercially  New  inorganic  events  of t h e s y s t e m ,  study.  Division  Gums  on  behavior  in this  Kelco  (Tic  viscosity  analyzed  nitrogen  for  content.  determined.  Moisture AOAC vacuum  to  determine  (2  g)  of  diameter  h,  the  each x  15  desiccator  until  very  weighings.  moisture  ashing  contents  accurately  mm d e e p )  which  in a  Drying  and w e i g h i n g  weighed  were  were  difference  of  the  into  in were  aluminum  been  weight carried  dried,  for  to  ( 6 5 mm  cooled at  a  for  moisture  1 h  between  in  100°C  minimize  additional  existed  Samples  dishes  i n t h e oven  quickly  repeated  1 4 . 0 0 2 ) was u s e d  polysaccharides.  dried  and w e i g h e d  Four d e t e r m i n a t i o n s  content  of  1980, Section  had p r e v i o u s l y  Samples  desiccator  little  method  (AOAC,  gum w e r e  Ash and I n o r g a n i c Ash  oven method  and w e i g h e d .  cooled  pick-up.  2.  well  was u s e d  ash,  The  3  the gross  (Keltrol,  moisture,  conclusions  a reasonably  bean  Intrinsic  draw  from  approach  xanthan  1.  to  periods  successive  o u t f o r e a c h gum.  Components the  o f t h e AOAC  polysaccharides (AOAC,  was  1980, Section  obtained 14.006).  using  the  Crucibles  dry were  -  acid  washed,  cooled were a  in  then  a desiccator,  weight were  was  and  obtained,  mL  0.5%  using  an  Plasma  Atomcomp  dilutions  of  bean  were  gum)  sodium  using  (Perkin  3.  the  Nitrogen  of  flasks  g  of  the  which  (190:4  addition  digested  by  heating  was  diluted  was  36 h .  plasma Co.,  550°C, cooled until  Four  residual  for  a  constant  a s h was  range  of  Jarrel-Ash  MA).  and  10  determinations  spectrophotometer,  diluted  inorganic  spectrometer,  xanthan  in  determinations  Waltham,  x for  overnight,  polysaccharide  repeated  The  Further  x for  of  locust  potassium  Perkin  Elmer  and 306  CT).  organic clear  with  quantitatively  10 to  was  carried  Soltess  (1973).  polysaccharides  had  w/w)  by  flask  (100  absorption  and  followed  of  coupled  of  and a s h e d a t  analyzed  0 . 5 % HNO3 f o r  Norwalk,  Concon  Kjeldahl  traces  g)  Scientific  determination  0.15  mixture  (1  550°C  Content  balance,  HgO  Samples  process  and  solutions  made w i t h  Nitrogen technique  ca.  polysaccharide.  (Fisher  Elmer C o r p . ,  at  approximately  inductively  atomic  furnace  crucibles  This  HN0 3  above  an  muffle  into the  each  -  weighed.  w h i c h was  for  with  components  a  reweighed.  c a r r i e d out 100  in and  a c c u r a t e l y weighed  desiccator  to  heated  19  been  was  of  2.3  with  material  and mL  added mL  to  had  distilled,  were  the  digested cooled  deionized  volumetric  flask  a  micro  Mettler  weighed  sample  addition  When  the  and  of  the  and  and made  This  until  solution the then  up  to  dry  g K2S0lt  samples  (30%)  slightly,  water  2.3  The  H2O2  and  clean,  mixed.  H^SO^.  Kjeldahl  analytical  into  A catalyst,  concentrated  been  using  Using  washed.  periodic  colorless.  a 25 mL  acid  out  -  was were all  in  the  digest  was  transferred volume.  An  -  aliquot a  of  this  Technicon  NY).  The  of  diluted  obtained  for  Model  by  mixing  s o l u t i o n s were the  the  xanthan  solution then  solubilities, and  an  with  of  water  insoluble of  galactose  association the  locust  considered  most  well  as m i n i m i z e  or  unsuitable  e.g.,  for  30  min  for  these  at  1973;  likely  oxidative  or  to  reasons.  (Dea  (ca.  Polytron  were  0.1%)  were  Homogenizer,  NY)  into  Locust  10 min a t  three  80°C,  fractions  fraction,  a  on  the  0.1  bean  M gum  in order  to  molecules  maximize  for and  et  or  min  differ-  water  soluble  correspond main  chain  al.  at  70°C  Morrison,  1975)  with  substit-  hydration  1977).  dissolution  to  increase.  lightly  restrict  reactions.  90  of  substituents  unsubstituted  Morris  hot  fractions  galactose  hydrolytic  stirring 80°C  of  gum  gum  Westbury,  These  between  bean  was  min,  substitution  number  used  1978),  weight  1981).  residue.  (Whistler,  workers  stirring for  soluble  cold  solubility  other  Tarrytown,  content  sodium a z i d e .  a  decrease  by  0.02%  c o n s i s t s of  i n c r e a s i n g as t h e  regions  (2  gum t y p i c a l l y  solubility  uted  using  b a s e d on d r y  nitrogen  bean  Inc.,  and L a u n a y ,  degrees  interchain  gums,  containing  different  Strong  of  locust  Instruments  heated  bean  and  individual  gum ( D o u b l i e r  Locust  fraction  of  Brinkmann  sodium c h l o r i d e  ing  Systems,  % N values  estimates  content  sample.  solutions  PT10/35,  dissolve  nitrogen  Industrial  converted  Five  for  Viscosity  Stock prepared  (Technicon  were  used.  each  Intrinsic  4.  II  values  polysaccharide  -  s o l u t i o n was a n a l y z e d  Autoanalyzer  nitrogen  20  of  The the  method gum  Some methods (Sharman were  and  et  as  used al.  considered  -  The min t o  remove  The  air  and u n d i s s o l v e d  i n xanthan  stock  well  to  0.1%  as  0.1  for  locust  Fenske,  calibrated  carried  out  meter  to  viscometers tion  was  constant,  bean  No.  for  200  in the  constant term,  kinematic  constant supplied  k2/t2  formed  was  considered  the  stock  (mol  wt  cut-off  (Eq.  4)  and H u g g i n s  functions and  of  of  a  viscosity  P  in  small (Van  obtained  12,000 (Eq.  with  of  these  a No.  by  chloride  solutions (Z13)  capillary  Calibration for  the  as  Cannon  evaluations  solving  to  and  100  Cannon-Fenske  oils  process.  xanthan  Additional  =  k  l  t  +  were visco-  of  the  calibra-  ^ I  5)  -  good  agreement The  fraction Wazer  et  methods  converting  s p e c i f i c v i s c o s i t i e s (nsp)«  al.  against were  with  kinetic  (<0.06%)  by d r y i n g  14,000)  after  C 3 ]  centistokes.  manufacturer.  negligible  s o l u t i o n were  =  was  the  only  sedimentation  M sodium  behavior.  standard  viscosity in  ki  by  flow  no  15  equation  p  The  0.1  Viscosities obtained  1 0 , 4 0 0 xg f o r  general,  to 0.075% f o r  calibrated  Newtonian  at  centrifugation  with  viscometer.  checked w i t h ki  where u i s the  were  capillary a  diluted  gum.  In  this  range 0.004  solution  using  check  were  in the  M NaCl  residue.  solutions after  solutions  concentrations  0.005  -  p o l y s a c c h a r i d e s o l u t i o n s were c e n t r i f u g e d  was o b s e r v e d  give  21  of  1963).  distilled  relative  calibration  energy the  kit  correction term  Concentrations  and w e i g h i n g  u s e d t o model to  the  after  water. the  and of  dialyzing Kraemer's  concentration  viscosities  (nrel)  -  (An  npel)/c  nsp/c  The  mean  nSp/c  5.  of  the  against  intercept  Duplicate solutions  of  Measurments Meter  of  were  taken  Sample  gum  used  with  for  and  (ca.  [n]2  graph  of  [4]  c  [5]  {in n r e - | ) / c i n m3  pH w e r e  against  c  and  kg"1.  using  in  obtained  for  distilled,  a Fisher  Pittsburgh,  0.1%  and  deionized  Accumet  Model  0.4% water.  230  pH/Ion  PA).  gum  in  by  water,  potassium  polysaccharide  and  prepared  in  a  determinations.  distilled  water,  only,  potassium  first  were  viscosity  in  xanthan  distilled M  0.4%)  prepared  for  prepared  2  20°C  intrinsic  were  bean  in  + k"  c  Viscoelastic Studies  Dispersions  were  Cn]2  Preparation  a)  locust  at  S c i e n t i f i c Company,  1.  chloride  of  polysaccharides  Rheological Studies  solutions  + k'  pH  B.  those  the  determinations the  (Fisher  = [n]  = [n]  from  -  i n t r i n s i c v i s c o s i t y IT\1  c gave the  Determination  22  1  dispersing heating hydroxide  potassium  reasons  the  required  twice to  dissolve  to  hydroxide.  the  as  case,  Solutions  then  of  diluting  concentration bean  of  later),  concentration  Xanthan-locust  to  M potassium  discussed  before,  required  this  0.6  hydroxide.  (for  similar  In  8 M urea,  M potassium  hydroxide  manner  gum  of  blends  were  made  then  held at  a  by  mixing  vacuum  on  bubbles.  After  each  blends  against  and  distilled  the  behavior dilute, were  this over  easy t o  water,  drying  of  of were  o r 1 M NaOH j u s t  weight,  the  80°C, Pulling  removal  of  air  concentrations  obtained  after  in  dialyzing  weighing.  total  polysaccharide  (1)  they  showed  range;  (2)  p o s s i b i l i t y of  by  weight  were  linear viscoelastic they  were  entanglements  relatively  and  (3)  they  shown  and  or  in to  a  bean  Table the  1  M NaCl  be  The  Samples f o r were their  by m i x i n g  ratio.  evaluated ionic  each  pH  concentrations  similar  of  for  desired  at  gum a t  manner  to  viscosity  prepared  i n the d e s i r e d  in  blending.  on 0.1  locust  combinations  blending.  effects  were  Studies  Samples  before  after  water  Flow  had  adjusted  blends  the  studies.  s o l u t i o n s were  gum  were  at  a i r bubbles.  polysaccharide  frequency  prepared  as  deionized  0.4%  remove  solutions  facilitated  and  because:  xanthan  concentrations  temperature  ca.  accessible  experiment  appreciably  10 min t o  solutions  then  prepared  handle.  shear  factorial  for  test,  minimizing  0.05%  dynamic  the  rheological  Steady Shear  and  of  individual  the  Solutions 0.10  weights  also  experiment  thereby  b)  -  samples  Concentrations chosen f o r  23  t h i s temperature  small  the  equal  -  those  in  the  strengths  experimental  ( T a b l e 1)  pH o f  to  the  with  prepared natural  solutions  in  pH. of  used  fractional and  either  urea The  1 M HC1  not  change  evaluation  either  of  distilled,  Xanthan-locust  equal  for  unit.  samples d i d  t h e more d e t a i l e d  0.20,  bean  concentration  by  -  Table 1.  24  -  T r e a t m e n t c o m b i n a t i o n s f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s f o r t h e f r a c t i o n a l 1 | a c ^ o r i a l e x p e r i m e n t a c c o r d i n g t o t h e scheme o f T a g u c h i L 7 (3 ). 2  Factors Concentration (% w/w)  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27  Temperature  25 25 25 35 35 35 55 55 55 25 25 25 35 35 35 55 55 55 25 25 25 35 35 35 55 55 55  0 0.05 0.10 0 0.05 0.10 0 0.05 0.10 0 0.05 0.10 0 0.05 0.10 0 0.05 0.10 0 0.05 0.10 0 0.05 0.10 0 0.05 0.10  0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05  From T a g u c h i ' s L 7 2  Ratio,  (°C)  Ionic Strength (M added N a C l )  xanthan:  (3  pH  Gum R a t i o 2  Urea Concentration (M)  1 4 1 1 4 1 1 :1 4 1 1 :4 4 1 1 4 1 1 4 :1 1 4 1 :1 1 •4 1 1 4 1 1 1 4 1 1 4 1 1 4 1 1 4 4 1 1 4 1 1 1 4 1 .1 4 1  0 2 4 4 0 2 2 4 0 4 0 2 2 4 0 0 2 4 2 4 0 0 2 4 4 0 2  6 3 9 3 9 6 9 6 3 3 9 6 9 6 3 6 3 9 9 6 3 6 3 9 3 9 6  ) f r a c t i o n a l f a c t o r i a l design  l o c u s t bean gum.  (Taguchi,  1957).  -  2.  Rheological a)  Viscoelastic Properties  gum  and  viscoelastic blends  of  properties  the  two  Weissenberg Rheogoniometer, Regis, in  England).  the  different  manner. Data  Samples  were  frequency  for  20  evaluated at  collected  at  nine  the  equally  parameters  the  distilled  water  and 0 . 6 M  500 pm.  and  plate  thickness  or  and i f  simply bar  (9.4  Saddle  Brook,  NJ)  60°C  range  in  water of  of  the  0.6  to  and  in  range  0 to  60°C  for  60  s"1.  the  effect  blend,  of  data  5°C then blends  of  preliminary  at  evaluated  similar  intervals  were  also  a  at  the were  10  C°  prepared  in  KC1.  plate  when  cm i n d i a m e t e r ,  effects The  to  less  are  was u s e d t o m a i n t a i n  were  geometries  1975).  difficulty  PG2  platen  used w i t h  generally  was  a flow  of  as  cone  required  gap  than w i t h  the  c a n be  supported  c i r c u l a t i n g bath  a gap  advantageous such  The  s i g n i f i c a n t , these  upper  A Haake  are  other  (Walters,  and v a r i e d w i t h  Pa c m 3 / p m ) .  fixtures  compared  cylinders  mathematically.  torsion  blends  and  evaluation  a  polysaccharide  intervals.  Parallel  inertial  in  using  Bognor  spaced, logarithmic  7.5  co-axial  20°C  logarithmic  properties  fixtures,  testing  c a n be s e t  geometries  temperature  plate  oscillatory  spaced,  For  over  for  equally  viscoelastic  at  locust  Ltd.,  frequency  blend.  intervals  of  the  solutions  Viscoelastic  thickness  over  gum  only f i v e  Parallel  obtained  individual  on  xanthan,  (Sangamo-Schlumberger  at  were  of  obtained  solvents  the  solvents  R19  were  the  were  different  Model  water  solutions  of  the  of  in  of  Viscoelastic properties  collected  evaluations  more  -  Measurements  Dynamic bean  25  treated by  (Haake  f l u i d through  other  the  a  #7  Inc., lower  - 26 -  platen  (a  desired  modified  polysaccharides to  0.23  60°C.  experiments  exhibited  at  20°C,  Therefore,  dynamic  increasing  function erratic  resulted  from  decided  to  results  could  during  modulus  of  appearing  time,  behavior out  to  meter of  of  the  relatively be  of  aqueous  1.9  runs  (see  s"1 were  to  produce  solutions strain  and 0 . 0 4  the  of  the  range  of  0.19  at  to  carried  leave  the  slow at  after  this  Excess  a thin  out  with  a  loss  modulus  (G"),  the  loss  tangent  (tan  5 h at  1  20°C.  possibly  h  it on  was the  the  viscoelastic  and c o n s i s t e n t  reproducible  placed  around  removed  was  Model  used  (stress)  at  to  the the  703A  sample time  of  digital  monitor  voltage  signals  (G1),  a measure  the and  signals. the  s t o r a g e modulus  during a cycle  a measure 6), the  slowly  Therefore, for  A Tronotec NJ)  a  This  change of  was  and o u t p u t  v a l u e s of  elastically  film.  was  after  edge.  was  oil  Franklin,  p h a s e d i f f e r e n c e b e t w e e n t h e two  the  time  I)  h.  aging  r a t e of  Silicone oil  (strain)  energy  3  sample at  the  the  off  the  Inc.,  From t h e s e d a t a ,  level after  (Tronotec input  to  observed  period. only  Appendix  was  samples  obtained. aging  stored  that  experimental  T h i s was b e c a u s e t h e  the  measurement  amplitudes  the  evaluate  p a r a m e t e r s was  phase  order  l i n e a r v i s c o e l a s t i c i t y in the  storage  drying  rheogoniometer.  edge  in  0.19.  The  60°C,  indicated  using a frequency  all  maximum s t r a i n o f  At  fixture)  temperatures. Preliminary  0.04  Ferranti-Shirley  of  ratio  the of  were c a l c u l a t e d u s i n g a program w r i t t e n  of  energy energy  for  sinusoidal  deformation;  d i s s i p a t e d as h e a t lost  an A p p l e  to II  of  energy  and  stored,  microcomputer.  -  b)  Steady Shear Flow  Steady  shear  Synchro-lectric Lab.  Inc.,  sheared  from  the  at  lowest  the  attained.  Scale  rotational  speed.  the  0.2  175  evaluated  and  range  10  using  and  a  10  C°  Inc.,  surrounding  the  at  xanthan-locust  formed their  under  these  natural The  College,  PA).  stress  and  bean  were  S60  shearing  value  decreasing  used  and  was  treatment  was  steps  varied with the  and l o w e r  in  of  geometry the  range  combination  l e v e l s of  evaluated  over  Temperature RM3  were  pumped  gum b l e n d s Equal  at  was  (Brinkmann a  were  since firm  proportions  achieved  through  No d a t a  0.2%  temperature  bath  fluid  viscometer.  concentra-  the  control  circulating  all  calibrated with  (1.044  Calibration  at  were  the  with  were  experiment.  which  of  Samples  of  the  jacket obtained  gels  two  were  gums  at  oils,  S6  used.  constant  values  NY)  conditions.  viscometers  poise)  2)  Engineering  constant  using  each  upper  Model  cylinder  pH w e r e  (0.7775  calibration  outer  of  speeds  nearly  recorded  intervals.  Westbury,  a  Brookfield  (Brookfield  rotational  viscometer  the  using  cylinder fixtures.  factorial  (Table  Lauda-Brinkmann  10°C for  the  out  LVT  range covered  subsamples  strength  60°C at  Instruments  rate  of  fractional  and  until  then  corresponding to  ionic to  were  model  RVT  highest  speed  shear  Four  the  Samples tion  The  carried  co-axial  the  highest  s"1. for  to  were  Models  with  readings  fixtures  to  studies  MA)  -  Properties  Viscometers,  Stoughton,  continued  of  flow  27  could the  was be  poise), checked used  to  rotational  viscosity  (Cannon at  both  convert speeds  standard  Instrument 25  and  scale for  the  Co.  40°C.  The  readings RVT  to  State same shear  viscometer.  -  However, tional two  a different  speed  of  temperatures  Table 2.  28 -  c a l i b r a t i o n constant  t h e LVT  viscometer.  The  was r e q u i r e d calibration  for  each  constants  rotaat  the  w e r e e s s e n t i a l l y t h e same.  Summary o f v a r i a b l e s Fractional Factorial  and l e v e l s Experiment  used i n  Taguchi's  Level Variable  1  C o n c e n t r a t i o n (% w/w) Temperature ( ° C ) Ionic Strength (M added N a C l ) pH Gum R a t i o ( X : L B G ) U r e a (M)  Shear (n,  Pa  s)  purpose (Fox fit  calculated  together  and G u i r e , o f t h e power  with  m  behavior (Haugen value  is  1976).  using  0.05 55  0 6 1:4 0  0.05 3 1:1 2  0.10 9 4:1 4  using  Least  l a w model  the  index. and  0.10 35  squares  (Eq.  values  of  the  was  the flow  program  viscosity  written  statistical  for  package  this MIDAS  r e g r e s s i o n was u s e d t o e x a m i n e  6) t o t h e t r a n s f o r m e d  coefficient  The K r e i g e r - M a r o n 1976),  of  n = l o g m + (n - 1)  consistency  Tung,  ( Y , S " 1 ) and a p p a r e n t  a computer  the f a c i l i t i e s  log  where  0.20 25  s t r e s s ( a , P a ) , shear rate  were  3  2  (Pa  data.  [6]  log y  sn)  and  n  is  c o r r e c t i o n f o r non-Newtonian  applied behavior  to  recalculate  index  the  each  evaluated  from  the  flow  behavior  shear  rate  the  data.  -  The  coefficients  goodness rate  3.  of  of  fit  of  evaluated  using  were  plot,  four  calculated  apparent  power  solvent  as  a measure  viscosity  law  at  a  of  shear  parameters.  the  performed  on t h e  of  main  package  for  UBC  computer.  over  was  20  which  r e p l i c a t i o n s of rerun  examined.  loss  Genlin  The  at  the  60°C,  The  two  temperature  the  four  three  times.  (Greig  analyses  and  the  and B j e r r i n g ,  were  performed  within  This  gave  combination  of  loss  were  treatments  each t r e a t m e n t  Analyses  moduli  viscoelastic  and  each t r e a t m e n t - t e m p e r a t u r e  frequency and  on  design.  plots  experiment  storage  solutions  experimental  as t h e  entire  treatments  gum  T h e r e were t h r e e  levels  UBC  of  the  bean  split-plot  nine observations  statistical  were  Viscoelastic Properties  the  considered  and  of  of  of  a  five  the  r2,  Values  xanthan-locust  randomized.  the  model.  -  Analysis  effects  properties  total  the  Evaluation  The  were  determination,  50 s " 1 w e r e c a l c u l a t e d f r o m  a)  a  of  Statistical  levels  of  29  variance  tangent  1980),  at  were  using  the  available  separately  a  for  on  each  frequency. The as  the  normality  form. the  logarithmically  The  unclear fully  as  met.  balanced  treatment  to  whether  However,  design,  interpreted  assumption  variability  different  with  transformed  the  was  between  well  the  confidence.  was  assumption  because results  met  the of  the  were when  standard  combinations the  data  the  large  homogeneity  analyses analyses  were of  for  data  deviations  fairly  of  used  analysis  were  of  the  and of  in  this  means  this  made  variance  performed variance  the  on  could  a  for it was  fully  still  be  -  Means analysis  for  of  standard  the  variance  errors  difficulties significant  and  arose  Steady  The  the  evaluated.  Shear  of  gum  The of  of  total  ratio  and  levels  variance  of  at  rate  of  50  difficulties  the  not  in  presence  of  compared  after  estimating  degrees  involving  gum urea  the  were  coefficient,  shear  were  the  appropriate  of  freedom.  missing  data  These  as  well  as  replications.  Studies  consistency a  of  associated  because  effects pH,  Analyses  because  -  treatments  i n t e r a c t i o n terms  b)  strength,  various  30  - 1  on  steady  factors  carried  flow  s  concentration,  behavior  .  The  shear  used  out  are  on index  flow  data  and  was  the  ionic  behavior  summarized  the  analyses  temperature,  in  Table  obtained  2.  for  apparent  performed  were  the  viscosity  for  a  3-level 13  fractional outlined  factorial by  Taguchi  program  written  Systems  Inc.,  properties at  two  levels two data  of  the  apparent  coefficient  Genlin and  logarithmically  bean  at  a  (Greig the  before  scheme  were  carried  calculator  effects  gum s o l u t i o n and  ionic  plots  over  Analyses  coefficient, shear  rate  and B j e r r i n g ,  apparent the  1880  the  on  in  strength  which  of the of  50  s  1980).  viscosity  were  at  50  a n a l y s e s were c a r r i e d  shear  s  - 1  out.  flow and by  temperature  performed  Data f o r  a  Business  combinations  using  ))  using  evaluated  the  behavior  _ 1  out  proportions  v a r i a n c e were flow  (3  2  steady  Again  all  (L 7  (Litton  equal  in a s p l i t - p l o t design.  whole  consistency  Model  Temperature  randomized.  viscosity UBC  NJ).  concentration  the  according  Computations  Munroe  experiment  were  the  the  xanthan-locust  constituted  for  package  for  levels  factors  (1957).  Orange,  of  conducting  experiment  index  of  the  on  the  and  the  the  statistical  the  consistency  were  transformed  -  31  -  RESULTS AND DISCUSSION  A.  Composition of Materials Mean  nitrogen their  1.  values  contents  standard  for  for  xanthan  errors  ash,  major  metallic  elements  and l o c u s t bean gum s a m p l e s a r e  in Table  and  shown  with  gum  were  3.  Moisture The  moisture  approximately water  of  bonding  contents  11%.  hydration  amorphous  state,  2.  A s h and I n o r g a n i c  of  potassium  the  ions  biological  commercial reverse  humidities  normal  tend  to  a strong  of  contain  (Glicksman,  bean 8-10%  unsatisfied  easily.  Thus,  water.  using the  water  as  In  an  1982).  numerous  for  was removed  for  locust  xanthan bean  It  hydrogen  completely is  dry  unlikely  oven-drying  processing  gum  some  (Table of  chief  However, the of  polysaccharide  nature  s o d i u m as t h e  systems.  situation  hydrate  affinity  polyelectrolyte over  have  locust  that  technique.  Components  content  that  and  at  hydration  ash  than  sequence  of  xanthan  polysaccharides  have  the water  greater  both  Typically,  which  all  The  of  polysaccharides  positions  polysaccharides  for  moisture,  food  in processed foods.  3).  This  xanthan.  The  counterion  addition  of  products Thus,  the  was  considerably  may  be  a  predominance  present,  is  higher  results  of  expected  sodium c h l o r i d e  usually  con-  during in  concentration  the of  -  32  -  Table 3. Summary o f n o n - c a r b o h y d r a t e c o m p o n e n t s f o r x a n t h a n and l o c u s t bean gum p o w d e r s b a s e d on d r y w e i g h t s o f polysaccharides.  Xanthan Moisture  Ash  (%)  Data  Locust  Bean Gum  11.5 (0.23)1  11.0 (0.05)  10.6 (0.23) 3.5  1.4 (0.16) 0.36  K  (%)  Na  (%)  1.6  0.13  Ca  (%)  0.090  0.105  Mg  (%)  0.104  0.048  Al  (ppm)  70  50  Fe  (ppm)  20  10  Cu  (ppm)  10  10  0.37 (0.073)  0.84 (0.055)  Nitrogen  1  (%)  the  (%)  i n parentheses are  standard  errors.  - 33 -  potassium  was n o t u n e x p e c t e d  chloride  were  not  added  f o r xanthan  during  the  as l a r g e  quantities  processing  of  of  xanthan  sodium  (Pettitt,  1982). Combining for  xanthan,  calculated amount  the molar  a total  from t h e percentages  known.  However,  acetate  substitutents,  neutralization  for  pyruvate  in  not  present.  utents with  fourth  and  locust  gram o f  effective  at  conformation.  are present repeat  valid  that  pyruvic  (1978)  of  to  of  acid  or  1.98  a  for  moles/gram  et  al.  1977).  the ion content of  obtained carboxylic  a l a r g e excess of ions i s  sample  substitution.  suggested  sites  10"3  the carboxylic  the  i s not  polysaccharide  neutralization  that  concentration,  x  The  containing  available  (Sandford  relate  used  units  p e r gram  to  unit  either  neutralized  potassium  substit-  corresponds  to  For comparable  Sandford pyruvate  acid  et  al.  values  (1977)  substituent  one  on  and every  unit.  combined  bean  ions  analysis.  sample  repeating  x 1 0 " 3 moles  every  suggests  of  M i l as  repeating The  per  also  incompletely  and  and p o t a s s i u m  i n the  moles  t h e r e s u l t s do s u g g e s t  a low degree  Rinaudo  1.11  of  a n a l y s i s to the degree  It  are  sodium  from  in  residues  number  i s not c o m p l e t e l y  substituents,  sodium  in the elemental  pentasaccharide  substitutents  residue  the elemental  acid  of  it  obtained  pyruvate  the  can range  no p y r u v a t e  Although  of  assuming  where  of  o f 1 . 5 5 x 1 0 " 3 m o l e s p e r gram o f p o l y s a c c h a r i d e was  or d i s t r i b u t i o n  a  contributions  molar  gum b l e n d s  in  polysaccharide. lower At  contribution equal  of  calcium  proportions  Holzwarth  concentrations concentrations  than as  (1976) Na+, low  ions  i s about found  for  2.4 x 1 0 " 3  that  Ca2+  in stabilizing as  xanthan-  0.0005  M  moles  was more  the  xanthan  CaCl2,  the  - 34 -  conformation at  of  purified  temperatures  and  Milas  towards  of  (1978)  also  found  that  counterions,  effects  of  have  n o t been  ions  have  some  might  polyuronates  effect  (polyanions) Ca2+.  gel network The  significant  decreasing  the s o l u t i o n  transition  Thus,  the  into  xanthan  to  with  compared  to  properties  ionic  If  for, of  with  these  of  (Milas  no e x t e r n a l  for  salt  This  added w e r e  are  by  to the of  c a n make  and d e c r e a s e s not  taken  can  and f o r  transition is  into  be  drawn i n the  xanthan, process.  independent  own c o u n t e r i o n s  In t h i s  a  Ionic  i s important  viscosity  xanthan  1979).  rise  solution.  conclusions  of t h e p o l y m e r ' s  and R i n a u d o ,  by t h e  1982).  the  order-disorder  temperature  of  binding  solution  effects  the polymer.  the  of  these  f o r the formation  concentration  misleading  once t h e c o n t r i b u t i o n  account  polymer  induced  cation  et a l .  strength  gum  Gelation  is  that  responsible  such as i n t r i n s i c  temperature  system.  chains giving  (Rees  bean  i s possible that  and p e c t a t e  considered  is  increasing  properties  It  in a polyelectrolyte  the  corrected  transition  concentration taken  when  Rinaudo  selectivity  xanthan-locust  o f two p o l y m e r  concentration.  and  of  is  zones,  present  the  interacting  polysaccharides  contribution  determination  of  in these  increases  the  it  junction  counterions  consideration  the  However,  of  on  e . g . , alginate  and g l y c o s i d i c o x y g e n s  about  changes.  greater  calcium,  in detail.  on  carboxyl  b o x " model  ions  studied  of  with  t o be s t a b i l i z e d  rotation  exhibited  especially  presence  strength  xanthan  divalent  interaction  the  by o p t i c a l  appeared  counterions.  The  "egg  ( 0 . 6 mg m L " 1 )  8 0 ° C as j u d g e d  divalent  monovalent  xanthan  study,  c o n s i d e r e d t o have  of are  solutions low i o n i c  -  strengths. tion  was  used  roughly shear of  In d y n a m i c  the  studies,  counterions solution  3.  to  The Table  protein  content  gives  xanthan.  protein  the  4.  the  of  major  the  the  bean  a higher  xanthan  2.28%  over  the  contribution solution  gum  is  and  may  and 5 . 2 6 % gum  to In  have steady  narrow  of  the  still  for  locust  procedures  bean  probably  gum  range polymer  influence  protein  of  protein  for  a  known  than and  xanthan.  be The  effect  of  (% N x  twice  removal  therefore  in  Nitrogen  or that  would  associated with  Complete  The  shown  content  legume  a r i s e from d i f f e r e n c e s i n the manufacturers.  gum  respectively.  from  would  than  of  bean  s a m p l e was more  derived  proportion  isolation  locust  estimates  bean  i n t e r a c t i n g system i s not  The  of  varied  extracellular polysaccharide.  content  Other  strength.  crude  locust  a c c e p t e d by t h e d i f f e r e n t on t h e  of  into  values  of  have  similar  difficult  ionic  However,  contents  Locust  bacterial  using  solution was  expected  the p o l y s a c c h a r i d e s .  nitrogen  to  be  strength  3 c a n be c o n v e r t e d  expected  would  to  0.2%.  ionic  of  solutions  concentration  -  same p o l y s a c c h a r i d e c o n c e n t r a -  Content  This  the  0.05 the  6.25).  of  all  contributions  behavior  Nitrogen  so  solution  approximately  -  shear s t u d i e s , the  throughout  same  35  of  it  be than  protein  somewhat  more  differences  quality  in  standards  protein  content  specifically.  Components pure  polysaccharides in  p o r t i o n of  the  question  remainder of  the  are  considered  samples a n a l y z e d .  to  comprise  However,  it  -  is  possible  hydrolytic  5.  that  small  estimates  of  shown  Figure  were  2.07  method 1.52  and  4  m3 k g " 1  intrinsic  Huggins'  and  The  of  Figure  5,  corresponding mean  these  visosity  polymer m o l e c u l e s to  of  values  these  either  the  It  molecular  effects  dependent  on  is  obtained  the  particle  sufficient  would  at not  molecular  and  can  information  Additional dimensions  from  present.  alone  be is  of  the be  of  used  n  ~ n  limit  different  gum,  using  Kraemer's  gum w e r e  shown  in  these  1.43  Table  4,  s  of  volume  and as  accurate estimate  and R o s s - M u r p h y , contribution It  of  a of  1981). individual  i s defined  as  s c  n  m L  and  n , the  The and  provide  viscosity  s  infinite  present.  to  kg"1  a more  the  xanthan  bean  is  (Morris  polymer  weight,  of  d i l u t i o n where  intrinsic shape  of  estimates  the  inter-  viscosity  the of  J  is  macromolethese  where  available.  complications  vary with  m3  locust  may p r o v i d e  slightly  and l o c u s t bean gum as  solution viscosity.  concentration  solvent.  cular  be  For  and 2 . 1 6  values  i s a measure  overall  xanthan  for  two  c+o  is  might  respectively.  [n] = l i m  c  disaccharides  provided  both  method  two m e t h o d s  v i s c o s i t y than  Intrinsic  where  or  lipids  equations  using Huggins'  the  kg".  combination  mono-  as r e s i d u a l  intrinsic viscosity for  while  nr  of  Viscosity  Kraemer's  in  -  quantities  r e a c t i o n s as w e l l  Intrinsic  36  changes i n  arise  for  polyelectrolytes  ionic strength.  At  because  low i o n i c  coil  strengths,  - 37 -  Figure  4.  C o m b i n e d H u g g i n s ' (•) and K r a e m e r ' s (O) e x t r a p o l a t i o n i n t r i n s i c v i s c o s i t y f o r xanthan (0.1 M N a C l , 2 0 ° C ) .  to  - 38 -  Figure  5.  C o m b i n e d H u g g i n s ' (•) and K r a e m e r ' s (O) e x t r a p o l a t i o n t o i n t r i n s i c v i s c o s i t y f o r l o c u s t bean gum (0.1 M N a C l , 2 0 ° C ) .  - 39 -  Table 4.  I n t r i n s i c v i s c o s i t y and pH f o r x a n t h a n and l o c u s t bean gum s o l u t i o n s .  Xanthan  Intrinsic viscosity (m 3 k g - 1 0 . 1 M NaCl  pH  (0.1%  ^ata  solution,  Locust  Bean Gum  2.12  1.47  6.0 (0.27)1  6.1 (0.10)  20°C)  H20,  i n parentheses  20°C)  are standard  errors.  -  the  molecule  compact  adopts  form  repulsions  as  an e x p a n d e d  the  are reduced.  as t h e c o n c e n t r a t i o n compensate NaCl.  Rinaudo  strength  is  which  polymer  effect,  and M i l a s  collapses to  increased  in solution  and  ionic  intramolecular  strength  i s decreased.  is  have  reported  of xanthan  change v e r y  little  Newtonian  fluids,  intrinsic  that  the  reduced  In o r d e r  i n t r i n s i c v i s c o s i t y was d e t e r m i n e d (1978)  a more  to  in 0.10 M  conformational  above i o n i c s t r e n g t h s  of  M. For  shear  rate.  intrinsic ated  to  However  conditions  sufficiently independent The  of shear Huggins  highest tion  locust xanthan  of  the  bean  under  Morris  sity  m3 k g  1.67  so  behavior,  rates  shear.  should Low  no e x t e r n a l l y  capillary that  for  xanthan  at higher  data  be  shear  viscosities  of for  extrapolrates  applied  viscometers  viscosity.  interactions;  are  pressure.  will  provide  areessentially  f o r xanthan  slight  curvilinearity,  This  i s p r o b a b l y due  thus  for  among t h e v a l u e s  This  A range of v a l u e s a variety  shows  concentrations.  effect  (1981)  xanthan,  was l e s s  h a v e been  reported  the  used f o r e s t i m a pronounced  f o r the i n t r i n s i c v i s c o s i t y  of c o n d i t i o n s  and R o s s - M u r p h y - 1  data  was n o t i n c l u d e d  solutions.  obtained  rates  flow  shear  zero  with  intermolecular  intrinsic  literature. of  plot  concentration  of  to  i s independent  rate.  pronounced  presence  at f i n i t e  t h e c h o i c e of  shear  viscosity  i s non-Newtonian  viscometers  that  low  b e c o m i n g more the  there  the  corresponding  in capillary  i s anticipated  to  if  v i s c o s i t i e s obtained  generated It  conformation  For p o l y e l e c t r o l y t e s ,  of  for this  properties 10'2  ionic  40 -  in of  reported  in the  an i n t r i n s i c  visco-  gum i n t h e p o t a s s i u m  s a l t form  at 0.10  -  ionic m3  strength.  range  viscosity value  of of  values  l o c u s t bean 2.71  However, t h i s by  of  extrapolating  from  present.  Doublier  with  kg"  reports,  chloride  solvent.  v i s c o m e t e r were locust  solution  of  bean  gum  200 c a p i l l a r y  No.  100.  sensitivity.  this  the  of 8 . 0 0  intrinsic  Sharman  e t a l . (1978)  gum a t  a shear  flow  of  reported  rate  of  1 s"1.  value  of  1.47  locust  values  m3  bean  i n water  expansion,  using  the  higher than solutions,  0.02%.  ranging  except  since  longer  In c o m p a r i s o n in  this  viscosity.  sodium  chloride  dimensions  and  highest  a  solution  capillary  than  100 f o r  concentration. below  concentra-  v i s c o s i t i e s obtained lower  is  solution.  200 C a n n o n - F e n s k e  the  somewhat  0.77  gum i s l i k e l y t o be l o w e r  in the salt  Intrinsic were  from  k g " 1 obtained  intrinsic  coil  No.  both  a r e l i k e l y t o be  t h o s e o b t a i n e d w i t h t h e No.  u s i n g t h e No.  gave  0.10% where  behavior  reported  t o be l o w e r  viscometer  Data o b t a i n e d as  for  s o l u t i o n s , t h i s t r e n d was s e e n o n l y  approximately  No.  accurate  reported  concentration  (1981)  than  obtained  somewhat  However f o r x a n t h a n tions  high  v i s c o s i t y of  Molecular  Viscosities  a value  s a m p l e s o f l o c u s t b e a n gum.  the  h i s c o s i t y w o u l d be e x p e c t e d  all  bean  and n o n - N e w t o n i a n  and L a u n a y  intrinsic  sodium  poorer  been  seems t o be a r e a s o n a b l e e s t i m a t e o f  The in  also  gum s o l u t i o n s .  for different  literature  experiment  has  a rather  interactions  1.00 m  reported  s h o u l d n o t be c o n s i d e r e d r e l i a b l e a s i t was o b t a i n e d  molecular  to  (1981)  i n 0.80 M NaCl.  m3 k g " 1 f o r l o c u s t  value  -  Holzwarth  k g " 1 f o r u n p u r i f i e d xanthan A  a  In c o n t r a s t ,  41  those  using the using  the  100 c a p i l l a r y w e r e c o n s i d e r e d more  efflux  times  and  showed  greater  -  B.  Rheological Studies  1.  V i s c o e l a s t i c P r o p e r t i e s of In  modulus bean  Figure (G")  gum  tangent  are  and  the  shown  blends  i s shown  a)  6,  for  dispersions  could  be  frequencies,  the  development  of  in  curves  and  The  or  the  The  had  frequency  is  and  for  the  xanthan,  plot  the  plateau  of  moduli  distinct and  loss  contrast moduli  changed  value  for  of  of  of  region  polymer  are  in  over arise  molecules.  be c r o s s - l i n k e d .  xanthan  loss locust  the  loss  about  present.  the  or  from  However,  in  with  0.4.  At  range of  time at  long time  gum  those  of  increasing highest  polysaccharide  are  the becomes  (Ferry, or  by  result more  1980).  coupling  entangled  periods,  inter-  increased  with  interlocking periods,  bean  the  curves  frequency  with  molecular  weight  the  frequency.  total  which  low  slowly  than  little  G"-frequency  At  locust  Interactions  physical  short  changed  larger  0.4%  gum  indicated  increasing  molecular  G',  a wider  At.  systems  xanthan  regions.  with  very  at  of  moduli  were  increased sharply with  concentration  Entanglements  In  tangent  behavior  and e x t e n d s  two  storage  average  loss  i n which the moduli  time.  typical  polymer  and  storage  region,  entanglements  pronounced  to  (G1)  corresponding  into  the  loss  an  solution  increasing  appear  The  storage  of  of  the moduli  concentration,  segments  of  modulus  7.  or  values  moduli.  frequencies,  that  two.  the  a plateau  the  frequency  actions  the  divided  frequency  solutions, loss  functions  in Figure  curves  the  storage  Xanthan  The  changes  -  the Polysaccharides  dynamic as  of  42  of  molecules  entanglements  -  F i g u r e 6.  43  -  D y n a m i c s t o r a g e and l o s s m o d u l i f o r x a n t h a n , l o c u s t bean gum and x a n t h a n - l o c u s t bean gum s o l u t i o n s ( 0 . 4 % i n w a t e r 20°C).  at  -  44  -  oo  CM  r-j  -0.5  ,  0.0  1  1  1  0.5  1.0  1.5  1  2.0  FREQUENCY (LOG SCALE) F i g u r e 7.  Loss tangent f o r xanthan, l o c u s t bean gum and x a n t h a n - l o c u s t bean gum s o l u t i o n s ( 0 . 4 % i n water at 2 0 ° C ) .  -  differ  from  because  of  1977). cular ent  chemical thermal  Coupling forces  involves tions the  c r o s s - l i n k s in  motions is  and  usually  (Ferry,  chemical  results  in  that  the  the  and  in  The  increase' in  loops  interactions  and  presence  of  untie  lost  than  implies  rubber  the  can  are  rather  Cross-linking  linkages. an  -  topological  1980).  interactions,  covalent  45  (Bird  due  to  somewhat  polymer  et  perman-  rheology,  usually  or  elastic  a l . ,  intermole-  more  entanglements  s o l i d - l i k e or  themselves  interac-  properties  of  solutions.  b)  Locust  The  storage  increased  rapidly  with  those  loss  moduli  studied, the  loss  1980).  of  At  0.4%  energy  and  with  were  tangent  and  of  total  the  comparable  locust  be  bean gum.  in  solution  polysaccharide  was d i s s i p a t e d  as h e a t  to  is  during  no i n t e r a c t i o n s  (Ferry,  gum  at  differences  the  same  in t h e i r  of  the of  amorphous the  a  random a  all  polymer  of  The  value  polymers  solution of  locust  (Rees,  1972).  proportion  process.  solutions  of  (Ferry,  expected  coil  the  frequencies  3.  greater  deformation  compared  values  l i k e l y conformation  This  in which  of form  little  1980).  viscoelastic properties  solution  at  solutions  were  The  c l o s e to  concentration,  or  bean  that  blend.  with  gum  curves  moduli,  of  The most  is typical  in the  that  bean  when  being  correlated  v i s c o e l a s t i c behavior  Differences  storage  tangent  of  occur  locust  frequency,  the  loss  can  for  polysaccharide  than the  behavior  molecules  moduli  increasing  was  of  loss  larger  values  This  gum  Gum  xanthan  with  conformation bean  Bean  concentration,  solution conformations.  of  can  xanthan be  and.locust  correlated  Xanthan e x i s t s  in  with  solution  -  as  an e x t e n d e d ,  (Morris  et  1978).  There  al.  aggregates  1977; is  in  Southwick  helically  et  a  coiled  Whitcomb strong  solution  al.  1979;  entanglement  solutions  of  ences  the  i n the  differences reported xanthan  bean  of  of  (MW  *  1.4  some d i f f e r e n c e s  -  different  Locust  viscoelastic properties  Bean Gum  s i m i l a r , i n some r e s p e c t s , t o  moduli those the  for for  weight  the  blend  xanthan  loss  the  frequency  were  higher  gum s o l u t i o n s  tangent  were  as  In in  amorphous  that  differ-  Rinaudo  the  However,  of  and  Launay,  samples used were  exist  between  to the  unaggregated  and M i l a s ,  1978) 1981)  and are  not  estima-  molecular  weights  Solutions  of  xanthan-locust  t h o s e of  xanthan  bean  gum  solutions  solutions.  However,  r e g i o n was c o n s i d e r a b l y more p r o n o u n c e d , w i t h over  solu-  sources.  The  value  of  1977).  of  polymers.  Doublier  may  1977;  pronounced  solutions  two  1970;  of  al.  al.  more  form  and l o c u s t bean gum a r e due  the  106,  et  c o u l d be a r g u e d ,  molecular  al.  molecular weights  and  of  the  et x  It  in  et  Milas,  and  development  (Morris  than  xanthan  for  Dintzis  the  and  align  Morris  considerably  molecules  Xanthan  plateau  in  are  c)  constant  of  values  p o l y s a c c h a r i d e s from  were the  The  however,  results  configuration  Rinaudo  molecules to 1970;  molecular weight  2 x 106, gum  comparable. ted,  the  1978;  al.  same m o l e c u l a r w e i g h t .  literature (MW *  locust  rod-like  the  a rod-like  and r i g i d i t y  phenomena  solution behavior in  et  This  addition,  of  for  (Dintzis  considerable structure  polymers  Macosko,  tendency  1980).  -  molecule with and  tions with  rigid,  46  range and  alone,  much  as  of  the  0.6 loss  with ten  to  19  an e s s e n t i a l l y  s"1.  moduli  were  the  result  that  times  lower  than  The  storage  lower the  than values  those  for  -  xanthan an  solutions.  average  quoted  value  by F e r r y  -  The v a l u e s o f t h e l o s s of  around  0.03.  This  tangent  i s close  with  bean  less  gum  energy  solutions  of .more  numerous  or stronger  xanthan-locust  bean  weight  entangled  The e n h a n c e m e n t  seen.  properties  between  specifically  functional  and 1972;  to  xanthan  more  when c o m p a r e d  with  suggests the presence When  compared  to  that  of  either  cross-linked  high  polymeric  covalent  in  t o non-bonded localized  up when a single  in rigidity  rise  rubber in  bring  and r e d u c t i o n  that  about  the  in the viscous  of s p e c i f i c  cross-  bean gum s y s t e m s a r e n o t c o n s i d e r e d  bond  formation  elastic  regions  polysaccharide  of  to junction  order. zones.  sequences  polysaccharide chain 1977).  of  o r t o be o f t h e  theory  (Treloar,  gel  i n t e r a c t i o n s between  the ordered  R e e s and W e l s h ,  to  t o the development  i n xanthan-locust  used  were  solutions, i t i s unlikely  sufficiently  of  and l o c u s t bean gum (Dea e t a l . 1 9 7 7 ) .  resulting  giving  developed  attributed  involve  type  "cross-links" attributed  have  i s therefore  Cross-links  built  0.01  the v i s c o e l a s t i c behavior  or t o l i g h t l y  t h e same a s i n t h e i n d i v i d u a l  changes  involved  of  considerably  i n the blend.  corresponded  systems  would  leading  This  (1980),  gum s o l u t i o n s  entanglements  linkages  with  S i n c e p o l y s a c c h a r i d e c o n c e n t r a t i o n s and m o l e c u l a r w e i g h t  essentially  to  interactions  t h e s y s t e m s d e s c r i b e d by F e r r y  networks.  small,  the value  b e i n g d i s s i p a t e d as h e a t ,  s o l u t i o n s o f t h e same c o n c e n t r a t i o n .  molecular  to  showed  xanthan  with  were v e r y  (1980), f o r l i g h t l y c r o s s - l i n k e d polymers.  Xanthan-locust elasticity  47  The  have  been  two o r more c h a i n  A three sugar  interacts  1975).  formation  Several  sugar  with  are  several  segments  residues  dimensional  residues  tetra-  network  are is  interrupted  others  (Rees,  -  d)  Frequency  In and At  cross-linked  cross-links high  from  significance  to  these  configurational  entanglements  are  longer value  much  the  the  in  comparison  terminal  and  differences  The  the  it  possible  frequencies  to  the  that  A pronounced  a r e of  greater  times.  At  place  are  the  contrast,  not by  systems,  the  giving  rise  becomes phase  unchanged.  do  characterized  frequency  stored  low  beyond  entanglements  negligible  angle  the Thus,  uncross-1inked  not  observed and t h i s  viscoelastic  that  of  a lightly  experiments  allow the  frequencies),  polymeric  and  transition  between  moduli the  systems  for  greatest  are  seen  at  1980).  bean gum b l e n d s ,  to  and  network.  substantial  the  take  changes  In  relatively  zone was  that  which  heat  90°.  c r o s s - l i n k e d and  terminal  corresponds  as  a  In  relaxation  energy  the  (high  decreasing  region,  dissipated  (Ferry,  blends  this  remain  between  xanthan-locust  is  In  of  entanglements  short  with  entanglements  make  much.  uncross-1inked  sharply  both  moduli  behavior  These  approaches  systems  conclusion  add  significance  For  fall  that  to  moduli.  times.  zone. to  low f r e q u e n c i e s  not  changes  greater the  strain  cross-linked  for  to  moduli  to  stress  of  relaxation of  may  rise  that  entanglements  glasslike  give  Cross-Linkages  elastic  c h a n g e s w h i c h o c c u r between  and  and  assumed to  times),  frequencies,  contribute  is  cross-links  rubberlike  configurational  it  additively  (short  whereas  -  on E n t a n g l e m e n t s  systems,  contribute  frequencies  contribution, zone  Effects  48  were  observation  minimum was  of  observed  in  the  curves  lends  behavior  of  the  additional of  the  support  carried  the  terminal  in the  curve  to  polysaccharide  c r o s s - l i n k e d network. not  moduli  out  However,  at  low  enough  the  loss  moduli  zone. of  -  at  12  s  - 1  .  This  was  also  The minimum v a l u e a p p e a r e d frequency  and so was n o t  expected (Ferry, the  in  the  1980).  plateau  minimum which  G"  in  -  the  Effect  of  The  storage  Figure  9 as f u n c t i o n s  water.  Corresponding  The  moduli  F-ratios  and  Appendix  the  II,  temperature  by  used  Effect 20°C,  very  (0.6  increased  of  to  of the  little 19  the  KOH,  expected  loss  tangent.  to  that  A minimum  is  systems  e n c o m p a s s most  in  a specific  at  polymeric  to  point  and  of  frequency.  The  relaxation  process  Temperature  evaluated  for  and  the  at  urea  along  a n a l y s i s of  shown  Figure  8  and  blends  tangent  are  shown  in  variance for  the  storage  loss  the  in  xanthan-  curves f o r  in  Both temperature  Tables  Al,  and s o l v e n t  variation.  interaction  20 and 6 0 ° C f o r  are  with  summarized  s o u r c e s of  The  A2  indicated treatment  Figure  and  and  loss  A3  treatments  s i g n i f i c a n t (p  in  of  were  <  0.01)  e f f e c t s were  not  temperatures.  Urea storage with  s"1).  sharply.  the  polysaccharide chain.  KC1  are  entangled  single  due  frequency  values  solvent  same a t t h e two  changed  in  respectively. (p < 0 . 0 1 )  At  a  is  Treatment  tangent  significant  i)  of  of  minimum  probably  from the  loss  curve f o r  r e p l i c a t i o n s c a r r i e d out  curve  and l o s s m o d u l i  gum b l e n d s  in the  three  just  Solvent  bean  the  not  was  locust  10.  this  a r o s e f r o m movements  e)  in a l l  frequency  and  curve  reflected  -  considered a spurious occurrence.  However,  region  49  This  and  loss  moduli  i n c r e a s i n g frequency However, was  at  the  comparable  for over  highest to  urea  the  the  treated frequency  frequency, behavior  the of  samples range moduli aqueous  Figure  8.  Dynamic s t o r a g e (a) and l o s s (b) m o d u l i f o r x a n t h a n - l o c u s t i n w a t e r , 8 M u r e a , 0 . 6 M K C 1 , and 1 M KOH a t 2 0 ° C .  bean gum s o l u t i o n s  Figure  9.  Dynamic s t o r a g e ( a ) and l o s s ( b ) m o d u l i f o r x a n t h a n - l o c u s t i n w a t e r , 8 M u r e a , 0 . 6 M K C 1 , and 1 M KOH a t 6 0 ° C .  b e a n gum s o l u t i o n s  -  52  -  d qd  F i q u r e 10.  L o s s t a n g e n t f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r , 8 M u r e a , 0 . 6 M KC1 and 1 M KOH a t ( a ) 2 0 ° C and ( b ) 6 0 ° C .  -  solutions. slightly moduli those This  Values  lower than and  of  the  of those  loss  aqueous  the  indicates that  storage  of  aqueous  tangent  solutions more  53  for  -  moduli  solutions.  urea  over  is  entire  being  bean  results  gum i s  although tions,  not  suggest  greatly  between  urea  (Kauzmann,  and  1959;  tion  of  that  hydrogen  in  the  i n t e r a c t i o n of  system  does  take  molecules The  could  be  end  are  plays only a minor  considerably weaker,  such t h a t  they  suitably  orientated  strongest  when t h e  decreasing increase  However,  somewhat  (Richards,  for  in  unless the  can a p p r o a c h each o t h e r hydrogen  very  bond  larger  than  for  blends  with  locust  at  20°C,  urea  solu-  hydrogen  bonds  In  as  in  preference  be t h a t  These  the  1980).  importance  of  hydrogen  orientation  of  hydrogen  angle  xanthan-locust  aqueous shapes  solutions,  of  the  closely with  Therefore,  bonding bonding  in atoms  the  two  system  bonded  hydrogen  hydroxyl  Hydrogen  be  i n a l a r g e number o f  are  groups  bonds  are  strengths  participating  could  bean  molecules  a p o s s i b l e reason f o r this  suggest  s t r o n g l y hydrogen  formation.  between  aggrega-  results  p a r t i c i p a t i n g atoms a r e c o l i n e a r , w i t h bond as  studied.  8 M urea  formed  r o l e in the  solid  state.  loss  water.  place.  inhibited.  were  the  range  r e s u l t would  structures are  were  b o n d s become d i s r u p t e d  1978).  urea  both  xanthan  p r e s e n c e of  P o l y s a c c h a r i d e molecules form  bonds  blends frequency  gum i n t e r a c t i o n . i n the  20°C,  solutions in  by t h e  polymer  molecules  bonding  the  hydrogen  Lapanje,  polymer  the  disturbed  some d i s r u p t i o n  i n t e r m o l e c u l ar  that  in  d i s s i p a t e d as h e a t  made i n u r e a s o l u t i o n s when c o m p a r e d w i t h The  blends At  treated  the  energy  for  groups  the lack  of  unfavorable cases.  -  U r e a may a l s o have a s m a l l bonds  (Kauzmann,  saccharides  develop  Rees,  1969).  give  rise  appear  1959;  that  systems.  Although  molecule  (Holzwarth  et  a l . 1977),  not  known  exists  in  extended with  saccharide alkyl are  as  (Dea e t  carries  al.  1972,  a large  substituents,  coil  found  be  minimal of  Moorhouse bean  suggested  molecule,  in the s o l i d  1977).  In  proportion  of  so t h e p o s s i b i l i t i e s  it  and  the  would  this  is  interacting  helically  coiled  e t a l . 1977;  Morris  gum i n s o l u t i o n  that  locust  which  on  addition,  to  the  interaction  neither  side  is  bean gum  reverts  state,  non-polar for  poly-  (Kauzmann, 1959;  results,  as a  locust  h a s been  random  conformation  of  on  polysaccharides could  the  solution  1977;  conformation  a  From  would  in  and P r e s t r i d g e ,  It  coiled  hydrophobic  sites  helices  conformations  exists  certainty.  ribbon  xanthan  solution  xanthan  solution  coiled  interactions  the exact  with  of  interactions.  proposed  i n weakening  Hydrophobic  of two h e l i c a l l y  hydrophobic  with  1978).  on t h e i n t e r i o r  hydrophobic  consistent  direct effect  Lapanje,  Interlocking  to  54 -  poly-  groups, e . g . ,  hydrophobic  interactions  limited.  ii) For were  Effect both  almost  o f Added  Electrolytes  KOH and KC1 t r e a t e d  linearly  increasing  functions  moduli  i n c r e a s e d much more  rapidly  moduli  being  the  both cross  greater  cases.  At  over,  so  becomes  larger.  than  intermediate that  at  the  The changes  samples, the storage  than  storage  in  the  frequency.  the loss moduli  frequencies, highest  of  moduli,  at  lower  the storage  frequencies, storage  and l o s s  the  and l o s s  The with  moduli storage  the  frequencies  loss in  and l o s s  moduli  storage  moduli  moduli  c a n be  -  interpreted  as  a  change  from  frequencies  (long  times)  to  higher  frequencies  moduli  When  blends  were  lower  at  higher  for  both  values  the  loss  as  bean  occur  are  high f r e q u e n c i e s ,  cloud  In  solutions  of  tions  during  polar  of  Van  Waals f o r c e s  high  formation  between  ionic  xanthan-locust appear play  that  a major  in  bean  dipole role  or This  of  compared,  all  at  low  behavior  were  frequencies  than  at  changes  in  the  entanglements urea  ionic atoms  become  minimizes charged  induced  groups  From  chains  blends  interactions stabilizing  in of  the  also of  the  gel  or  to  or  by  a  degree  of  moduli  at the  M  KOH,  stabilizing interacRichards,  development dipolar in  viscoelastic  structure.  systems  1.0  1959;  the  reduced  general  The  samples.  and o t h e r  different  a rather  water.  electrostatic  leading  xanthan-  s i m i l a r l y to  (Kauzmann,  are  a comparison  in  0 . 6 M KC1  or  energy  for  storage  surrounded  ionic  dipoles  the  treated  e.g.,  similar  Thus  strength  in  values  cross-linked  contribute  and KC1  strength  made  for  similarities  20°C than  greater  those  behavior  at  larger  storage  difference  studied.  was  for  the  little  samples,  tangent  deformation  The  with  treated  (London d i s p e r s i o n f o r c e s )  gum  in  are  urea  KC1  polysaccharide  strength.  water  loss  at  water,  oppositely  The  actions  the  that  groups  1980).  behavior  solid-like  frequencies,  the  where  high  counterions.  liquid-like or  viscoelastic  for  or  elastic  and  cyclic  made  in  moduli  between  der  and  suggest  the  on  lowest  apparent.  of  charges  two  frequencies  cross-linking  more  KC1  water,  gum b l e n d s  low  a  As w i t h  differences  at  values  the  in  heat  viscous  in  moduli  samples  dissipated  greatest  at  -  times).  made  frequencies.  for  locust  (short  55  Dipole  inter-  solutions  of  properties  of  solvents, nature  of  are  it  would  likely  to  interactions  -  are  probably  bonded most  of  interactions likely  carboxyl  group)-dipole  to  and a r e fact  a  Steric carrageenan  fit  is  permanent  as  system  number  the  same  interaction  Bulky  are  owes  The  charged  dipole-dipole  however t h e  stronger latter  are  relatively  its  stability  interactions  contributor  to  substituents  can  It  approach  the  is  weak  to  are  more  1973).  two,  to  the  the  formed  that  xanthan  would  greater  of  gelling  c l o s e l y than  This  a level  stability  diminish  possible  each o t h e r  (Morris,  between  (e.g.,  considerably  1980),  these  1969).  type  causes.  induced  are  hydrogen  1977).  gels.  can  and  interactions  of  specific  monopole  probably  important  (Rees,  from  (Richards, These  more  fundamental  interactions  The  an  pectin  molecules of  of  like  and  can  two  enhance  than  the  that  seen  molecules. The  results  xanthan-locust (1980).  In  obtained  bean  gum  an e m p i r i c a l  saccharide  concentration,  increasing  salt  range  well  as  ( R e e s and W e l s h ,  and  bean  molecules  in  arise  large  drastically  degree  similar  interactions  very  co-operatively  locust  arise  from  the  probably  easily disrupted.  ability  than  o c c u r more f r e q u e n t l y .  that  -  importance  Monopole-dipole  dipole-dipole  likely  which  interactions  interactions. than  greater  56  0  to  saccharide possible  in  are  evaluation  concentration  when  The  proportion  study  i s much  differences the  the  proportion  in of  effects  opposite  found  in this  differences  gels  he  4%.  that  here f o r  of  gel  of  the salt  gel salt  added  higher  than  that  electrolyte  reported at  1%  strengths  electrolyte that  total  used  to by  reached  on  by  Symes  total  poly-  increased  concentration  conclusion to  added  strengths  that the  to  of  was  with  in  total Symes. are  polysaccharide.  the poly-  It due  is to  Jeanes  -  et  al.  the  (1961),  effects  only  on  of  At  than  of  in  in  the  system,  The  those  values in water  frequencies. may  ments (Ferry, blends  have  varies  This  1980). were,  The on  the  water,  and  the  serves  noted  solutions but  also  that  depend  on  the  not  pH  or  about  of those  high  pH o f  as  this  of  the  1973). KC1 for  KOH,  storage  and t h e  other  suggests  that  purpose of  The is  KC1  in  also  the  polar  close  larger  system  as  interactions,  s i m i l a r i t y of  consistent on t h e  results is  with  nature  solvent the  concentration of  in greater  capable  moduli  somewhat.  average,  were  tested.  of  this  the and  cross-links  here.  solvent  recovery  frequencies  tangent  disruption  and  drawn  all  loss  similar  the  KOH  at  hydroxide  tested.  a  (Whistler,  decreased with  xanthan  have  b l e n d s made i n p o t a s s i u m  frequencies  s y s t e m can a l s o be drawn  bonds.  tions  bonds  for in  moduli  brings  the  (1983)  concentrations,  blends  all  s i m i l a r to  interacting  than  of  curves  However,  of  al.  polyanion.  hydroxide it  G' , G " - f r e q u e n c y  the  et  Alkali  at  hydrogen  conclusions  of  loss  water  that,  including  viscosity  the  Southwick  storage moduli  the  Potassium KC1,  on  those  both  t h o s e of  and  of  20°C the  -  (1980)  polysaccharide  Effect  lower  Values  or  ionization  iii)  than  salt  salt  degree of  were  Symes  57  for  of  entanglement The  or  number  molecular  non-dialyzable  somewhat  higher  disrupting  blends  treatments  or  d i s r u p t i o n of  in even  at  the in  density  of  solids  covalent  were  density  weight  than  KOH  the  KOH  lower highest solu-  entangle-  of  the  polymer  from  KOH  treated  those  of  the  other  -  solvent  systems  solubility lower the  of  except  cause of t h e  linkages the  is  above  have  hand  up t o pH 11 this  that  are r a p i d l y  base  brought  alkali  et  known  degraded The  reduction of  a l . 1961;  Rocks,  specifically.  above  pH 1 0 . 5 ,  glycosidic  linkage  presence  of  electron  withdrawing  elimination  reaction  reaction  begins  s u c c e s s i v e sugar  in  a stepwise  manner.  to  competing  reactions  produced  by s i d e  This  occurs.  Isosaccharinic  hydrolysis  reaction  However,  the  samples,  were  water  or  proceeded the  and  solids  KC1,  on  the  not  of  t o be  reaction  No f u r t h e r acids  these  are  end o f  expected  to  after  dialysis,  average  somewhat  larger  smaller  as  would  extent.  viscoelastic  be  expected  However, t h i s  studies.  It  is  base  and  the molecule susceptible unit  c a n be if  this  from  the  on  those if  the  molecule,  the  than  in a  proceed  lost  under  The  from  for  (Dea and  1982).  produced  be  other  stable  sugar  are  stability  groups,  will  of  fairly  on t h e  is particularly terminal  is  e.g.,  the  stripped  192)  weight  its  (Aspinall,  degradation  (M.W.  glycosidic  heated  functional  being  stable  if  conditions,  reducing  base  but  generally  recovered  to a s i g n i f i c a n t  results  the  type of  reactions.  is  certain  residues  and a  1971)  c a n be i n i t i a t e d  at  the  solutions  especially  under  strongly  of  Galactomannans  However,  with  greater  Therefore,  in the molecular xanthan  conditions.  proceeds  the  are u n l i k e l y  hydrolysis  alkaline  degradation  to  1973).  i n the system  viscosity  (Jeanes  1975).  catalyzed  due  (Whistler,  catalyzed  about  The  pH i s n o t  Morrison,  probably  difference.  possible  could  in  is  of p o l y s a c c h a r i d e s  polysaccharides.  stable  This  polysaccharides  concentrations  It  urea.  58 -  dialysis.  KOH  treated  prepared  in  hydrolysis  had  i s not c o n s i s t e n t  with  possible  that,  hydrolysis  -  reactions  resulting  entanglements, suggested  the  have  that  Association  repulsion  meters  hydroxide  of  The  changes at  and  samples  larger  than  moduli  for  tangent other  but  samples  the  these  KC1,  urea  urea  of  (1969), groups.  reduced  Alternatively, of  by  by  could  viscoelastic  be  para-  potassium  fairly  strong  KC1.  parameters  those  of  and  temperature  the  temperature  the  the  fewer  obtained  the  KOH  values  The  20°C. were and  very  values  values  increasing  similar.  also  the  at  storage  very  were  from  20°.  moduli  the  became  at  somewhat  l i n e a r l y with  loss of  were  Except generally the  loss  The  loss  c l o s e to  of  KC1  each  treated  frequencies.  over  Over  Rees  a mechanism  disrupted  different  greater  temperature.  with  hydroxyl  disruption  Values  blends  for  the  treatments  quite  effect  tangent  blends.  values  gum  loss  of  corresponding  bean  and  values  increased almost  xanthan-locust detail  of  Such  viscoelastic  modulus.  corresponding  When t h e  gum  than  in water,  were  the  compared w i t h  storage  samples  at  the  in  and  ionization  l i n k a g e s not  smaller  prepared  mechanism.  groups.  about  and l o s s m o d u l i  water  of  in  were  molecules,  Effects  6 0 ° C when  storage  cause  in  bean  i o n i c type  Temperature  some o t h e r  charged  brought  iv)  frequency for  or  weight  p o l y s a c c h a r i d e c h a i n s becomes  reduction  have  by  can  of  similarly the  may  different the  alkali  -  molecular  place  xanthan-locust  electrostatic  of  taken  interaction  for  of  smaller  strong  and  responsible  in  59  blends  in  in  water  and  range  water  temperature  on t h e  of  0,6  in  5 to  were  range  viscoelastic properties  60°C,  most  5 to  M KC1  were  the  storage  sensitive  20°C,  the  examined  to  moduli  changing  storage  moduli  -  for  samples  the  moduli  i n water decreased  shape  (Figure  values  of t h e l o s s  with a  viscoelastic  (Figure solid  5 t o 5 0 ° C , then curve  (Figure  moduli  for  temperature tangent  14). 15)  KC1  under  elevated ordered tion  is  required et  al.  pi a c e .  1977),  a  the  the loss  viscoelastic  very  little  difference  tangent  liquid.  over  than  appeared  (Figure  to  16).  At  in the other  The  in the  storage  60°C,  range  G'-frequency than  Values  change  of  of  little  values  the loss the  loss  over  the  the  loss  of  These  in the e l a s t i c  or  changes  in  solid-like  i n KC1 a t 6 0 ° C .  viscoelastic  of  under  et  properties  temperature  interaction  1977).  of  interaction  low  lost  xanthan-locust properties ionic ionic  ordered  with when  xanthan At  strength,  the  conforma-  conformation  locust the  of  bean  strength.  and a random c o i l  The  xanthan is  and  of  i s disrupted  al.  of  the solution  conditions  of xanthan  and t h e  increased  the temperature  solvents.  i n d i c a t e an i n c r e a s e  (Morris  in  corresponding values at 20°C w h i l e the reverse  prepared  the  changed  passed from t h a t  region developed  samples  conditions  adopted  little  evaluated.  5 to 50°C  conformation  very  while  a l l frequencies  temperatures,  for  of  c a n be c o r r e l a t e d w i t h  different  be  curves  at  of b l e n d s in  frequency  temperatures,  a l s o became l a r g e r  behavior  Changes gum s o l u t i o n s  12),  G'-  higher  The s t o r a g e m o d u l i  f o r samples  characteristics  to  but at  V i s c o e l a s t i c behavior  that  treated  range  viscoelastic  (Figure  i n KC1 c h a n g e d  became l o w e r  was t r u e  and t h e  appeared  13).  to  little,  at 6 0 ° C , a plateau  (Figure  tangent  There moduli  f o r blends  very  gradually  11).  temperature  moduli  changed  60 -  bean  is  gum (Dea  transition  takes  - 61 -  m CN CM  F i g u r e 11.  E f f e c t o f t e m p e r a t u r e on t h e s t o r a g e m o d u l u s x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r .  for  - 62 -  F i g u r e 12.  E f f e c t o f t e m p e r a t u r e on t h e l o s s m o d u l u s f o r b e a n gum s o l u t i o n s i n w a t e r .  xanthan-locust  -  Figure  13.  63  -  E f f e c t o f t e m p e r a t u r e on t h e l o s s t a n g e n t f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n w a t e r .  -  Figure  14.  64  -  E f f e c t o f t e m p e r a t u r e on t h e s t o r a g e m o d u l u s f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n 0 . 6 M K C 1 .  -  65  -  o  •  o A  + X  0 V  °C 5 10 20 30 40 50 60  in  9-|  !  -0.5  1  0.0  0.5  1  1.0  1  1.5  FREQUENCY (LOG SCALE) Figure  15.  E f f e c t o f t e m p e r a t u r e on t h e l o s s m o d u l u s f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n 0 . 6 M K C 1 .  —  2.0  -  Figure  16.  66  -  Effect o f t e m p e r a t u r e on t h e l o s s t a n g e n t f o r x a n t h a n - l o c u s t bean gum s o l u t i o n s i n 0 . 6 M K C 1 .  -  Xanthan-locust al.  (1977)  which  reported  bean  that  increase with  gels  ionic  known.  strength It  occurs  at  Snoeren  is  increasing  and  same  Payens  time  scattering  and o p t i c a l  point  saccharide. increased both  Both  of and  the  the  cation concentration. melting The  in  temperatures ordered  It  helix  transition  change  would  then,  dominant are  forces  probably  resulting not  the  to vary  strengths that  as  to  correlate  of  the  poly-  temperature,  concluded  temperature  Since  that  K-carrageenan  l i n e a r l y with  occurred of  the  i s s t a b i l i z e d to (> 0 . 1 M KC1)  the forces present  at  gel  xanthan  (Norton logarithm with  bean gum s y s t e m s .  of  temperatures  (Morris  interaction  et a l . between  under t h e s e c o n d i t i o n s .  i n a gel s t r u c t u r e same  light  no c o r r e l a t i o n h a s y e t been made  of xanthan  t h e s e two p o l y s a c c h a r i d e s a r e s t i l l  using  1 9 7 9 ) and i t s r e c i p r o c a l  of x a n t h a n - l o c u s t  appear  of  xanthan.  concentration.  they  the t r a n s i t i o n  shown  ionic  systems  i n an a t t e m p t  coincided,  gum g e l s  order-disorder  and t h e  of  conformation  the  parameters  data  effect i s not  of  helix  However,  e x c e s s of 1 0 0 ° C a t h i g h  1977).  change  and  of t h e s a l t  little  The  bean  double  1 9 7 6 ; M i l a s and R i n a u d o ,  of  gelation  the logarithm  been  b u t show  xanthan-locust  techniques,  reported  The m i d p o i n t  also  of  et  points  temperatures  conformational  conformational  a l . , 1 9 8 4 ) have  and s e t t i n g  Dea  and s e t t i n g  o f t h e two p o l y m e r s .  d e c a l c i f i e d K-carrageenan  the gel point  et  gel  the  studied  experimental  simultaneously. (Holzwarth,  as  rotation  l i n e a r l y with  sets  melting  with  systems.  polysaccharide content,  melting  (1976)  in intensively  gel  sharp m e l t i n g  proportions  that  transition  the  have  on t h e g e l m e l t i n g  possible  the  -  are thermoreversible  the gels  d e p e n d e n c e on t h e r e l a t i v e of  67  20°C.  at elevated High  The  temperatures,  ionic  strength  appears  to  60°C.  enhance  These  may now  water  results  be more  elevated  the  a  68  interaction  of  suggest  important.  temperatures  to  -  that  xanthan  hydrophobic  Hydrophobic  because  non-polar  -  the  is  a  interactions,  increasing  temperature,  thus  (Ben-Nairn,  1980).  interaction strengthen  hydrophobic  non-polar  materials  (Kauzmann,  is  resistance 1980). lower  values  factors  the  applying  parameters the  parameters  procedure,  ures  should  other  affect  the  match  changes  region  the  greater  plateau the  method  at  the  at  from 1959).  s y s t e m as  negative  stability  with  of  electrolytes  region  in  of  the  tend  to  non-polar  system,  to  can of  the  KC1  be  the  from This  visco-  volume of the  the  fractional  molecule  at  at  60°C  (Ferry,  occurs  20°C.  at  variables  provide  apart  v i s c o e l a s t i c parameters.  in  in  the  All  at  other  v i s c o e l a s t i c parameters  temperatures,  compared,  of  water of  of  the f r e e  an e v a l u a t i o n  reduced  values  reduction  parts  evaluation  sufficiently the  on t h e  blends  different  are  effect  for  shapes or forms  in  (Kauzmann,  more  addition,  different  corresponds to  the  obtained  this  No  between  the  temperatures  By  to  a corresponding  plateau  than  become  stable  groups  change of  increasing temperature,  remaining constant,  elevated  which  With  movement  Thus,  leading  has a d i r e c t  increased with to  non-polar  energy  at  1959).  parameters.  solution  of  gum  interactions  b o n d s b e c a u s e t h e y d e c r e a s e s o l u b i l i t y of  Temperature a l s o elastic  free  In  bean  non-polar  endothermic  overall  of  locust  i n t e r a c t i o n s a r e more  Entropy c o n t r i b u t i o n s to the result  or  transfer  environment  with  the  lower  frequencies.  the  viscoelastic  to  frequency  extended. curves at adequate  In  range  order  different regions  temperature is  clearly  at  to  of  the  use  temperatoverlap.  effects, not  over  should  case  for  -  the  xanthan-locust  bean  conditions  low  under  properties. ionic  The  strength  evaluation were  not  of  is  since only aqueous  strength  also  not  a limited  comparison  of  to  bean  blends,  development  here  v i s c o e l a s t i c behavior  as  the  systems  corresponds,  systems  in  many  theory  cases  is  at  high  available  for  properties  concentrated  networks.  modified  holds  polymers w i t h m o l e c u l a r weight of 2  with  the by  x  xanthan 106  and  complicate the solution  molecules  relates  relaxation  is  as  and  times  samples  the of  locust  greater  rather than  a  qualitative  viscoelastic  Ferry  behavior  (1980). the  assumptions  It  is  xanthan-locust  inherent  in  bean  are  bean gum b l e n d s most  the  Rouse of  the  moduli  with  this  less  200,000.  The  than  In  rod.  molecules  molecu-  The of  domain  similar  to  Both  addition,  the  theory  approximately  polydisperse.  theory.  cross-  concentrated  However,  helical  flexible  for  system.  generally  rigid,  Theory  gum a r e b o t h  the  closely  s o l u t i o n s or l i g h t l y  values  the  a p p l i c a t i o n of a  on  models to  polymer  and  l a r weight  example,  The  i n V i s c o e l a s t i c Theory based  xanthan-locust  frequency  like  solutions  met.  for  in  viscoelastic  viscoelastic  are  the  solutions  exists  to range  in  described  a r e not  to which  are e i t h e r  polymeric  factors  the  change  conditions.  apply e s t a b l i s h e d mathematical  of  The  of  affected  applicable  Changes  obtained  polymeric  difficult  order  has  conformational  temperature  solutions.  results the  different  for  the  F a i l u r e t o Meet Some A s s u m p t i o n s  The  gum  where  Limitations i)  linked  ionic  method  -  system,  a p p r e c i a b l e under t h e s e  f)  of  of  gum  69  the  these xanthan  of  rod-  molecular  -  weight,  thus  behavior  at  (Ferry, of  these  molecules  concentrations  1980).  rod-like  Ferry,  DNA  (MW  5.8  decades  of  However,  attempts  by t h e  of  polymer  lower  106),  frequency  between  and  author  concentrated  their  of  the  flexible  a  at  concentration  a  plateau  estimate  points,  the  lead  region  to  a  properties  extending  of  average  solution  counterparts  viscoelastic  found  to  coupling  show  than  an e x a m i n a t i o n  x  several  -  interact  much  in  70  0.012  over gmL-1.  molecular  weight  meaninglessly  small  value. For theory  cross-linked  of  modulus  rubber  (Ge)  polymers,  elasticity  gives  gas  c is  the  the  and N o r t o n e t  amount  of  in  the  an  increase  links  gel  are  al.  flexibility will  of  the  value  stems  of  the  from shear  (among of  (1984) in  points.  the  things),  xanthan-locust  molecules  are  considered to  in  the  broken.  elastic This  modulus  bean be i n  Rubber with  relationship  it  is  average  from  distribution  unlikely  Holzwarth a certain that  molecules.  theory  hold  this  This  is  configuration also  provided for  for  entropic  exists  an e x t e n d e d  elastic  not  the  Although  there  gum  universal  relationship  stems  temperature  does  the  Mc,  above  chains.  molecules  R,  a Gaussian  implied that  for  1980).  The  polymer  have  and  networks),  other  xanthan  (Mitchell,  solution,  temperature  hold  state  [8]  polymer  (cross-linked  vectors  (1981)  because the  equilibrium  which  = cRT/Mc  coupling  and assumes  end-to-end  assumption  the  absolute  between  polymers  considerations the  T,  weight  rubber-like  of  concentration  constant,  molecular  relationship  as  Ge  where  the  predicts no  cross-  xanthan-locust  -  bean  gum  examined gum  blends and  in  To  As  a  mathematically  changes  result, i s very  the  the  not  over  the  r e l a t i o n s h i p to 22  Pa,  to  limited.  of Added  shape  greatest  range  xanthan-locust  bean  lead  to  a  small  as  properties  extensive  treat  the  as  of  of  the  three  a  viscoelastic in  liquid 0.02  frequency  than  occurring  in  M  presence of  the  viscoelastic  of  u r e a was  of  the  used  added  systems  range, solid  found  increased  that  without  systems  48% w / v , water.  much  solutions,  the  current gum  to  material  values  to  interaction.  had t h e  behavior  slowly  an even  of  M  KC1)  passed  from  0.02  that  with  and  of  a  loss  increasing the  hydrogen  changes bonds  in  concentration  considerably less Thus,  al.  storage  higher  least et  to  attributed  disruption  with  in 8 M urea,  (0.5%;  the  about  changes  Frangou  > G")  for  authors  However, study  (G'  more  any  Solutions  at  with  M urea  These  bean  curves  solutes  in 4 M urea.  by 4 M u r e a .  xanthan-locust  these  systems.  viscoelastic properties  The  in the  polymer  added s o l u t e s may b r i n g  compared  in 4 M urea.  xanthan  aggregates,  of  0.02  values  plastic  s t u d i e s are required  cross-linking.  in  urea  aqueous  r e s u l t s from  More s y s t e m a t i c  the  xanthan  viscoelastic  of  Solutes  percentage  i n s t u d i e s of  of  temperature  also  viscoelastic  been  ability  a s i m i l a r frequency  xanthan  KC1  averaged  been made i n t h e d e g r e e o f  perturbation  moduli  Ge  on  i s possible that in  the  that  this  have  Effect  It  over  apply  where  M  s u i t a b l e t h e o r i e s a p p l i c a b l e to b i o l o g i c a l  ii)  (1982),  0.6  studies  systems  systems.  with  water  date,  biological  having  to  or  -  MQ.  for  develop  water  attempts  systems  value  in  71  disruption  e a r l i e r conclusions  - 72 -  that  hydrogen  bonding  interactions  still  solids  and  the  moving  parts  of  of  both  the  moduli  have  been  on  the  increase  in  high  frictional  chain,  any  xanthan-locust  the  could  decrease  bean  gum  concentration  of  resistance  lead  brought  viscoelastic properties  when  M NaCl  is  a  that  at  shielded,  storage  compared  attributed  suggested  to  poorer high  in  a  aggregation.  obtained  in  this  in  solutes  do  using 0.6  directly  solvents  than  decrease  has  solvent.  lines  in  to  an  between  enhancement  about  by  rupture  xanthan  in  0.1  are  required  and  solute  al.  water.  of  1984).  this in  al.  supports  the  suggest  to  an that  gum  dissolved  to  c o n c l u s i v e l y the on  bean  that  properties.  concentrations  were  conclusion  viscoelastic determine  (1983)  and  opposite  xanthan-locust  also  because  repulsion  are  the  results  xanthan et  in  c h a r g e s on x a n t h a n  results  reduced  These  of  interchain  and  M NaCl  a decrease  Southwick  negative  results  affect  and  aggregation  these  been  The  et  in  M KC1  of  xanthan  (Lim  increase  However,  interaction  not  these  different  study  this  water  solvent  in  blends,  of  ionic strengths,  resulting  molecular  moduli  with an  increase  of  the  bonds.  loss  along  in  Alternatively,  offsets  show an i n c r e a s e i n t h e  that  role  polysaccharide  which  Studies  0.1  a minor  hold.  resulting  moduli  hydrogen  plays  More  viscoelastic  studies  effect  of  properties  biopolymers.  iii) The  C h o i c e of frequency  approximately xanthan-locust  covers bean  Frequency range the gum  used  range  in  system.  in  this  which For  experiment, many  changes  materials  0.6 may whose  to occur  60 in  s  - 1  ,  the  rheological  - 73 -  behavior  approaches  sively  more  difficult  oscillatory  shear  experiment, data  that  a viscoelastic  to  obtain  techniques.  corresponded  could  of  to  be c o l l e c t e d f o r  approximated  the  upper  lowest  samples  limit  of  accessible frequency  intervals.  the  fifteen  logarithmic  different  already  to  accurately  been  mentioned,  xanthan-locust not  bean  carried  systems,  the  and  this  could  the  viscoelastic  frequencies In range  or  The  is  be  is usually  appear  to  be  creep  or  stress  clarify  increase  period  principle  of  of  applicable  to  two  used t o  characterize  intervals  due  low  the  to  terminal  the  fact  frequencies.  lower  not  operating  here. bean  It  that  be has in  studies entangled  (Ferry,  1980)  Investigation gum  to the  zone  In  frequencies  the  ten  would  blends  at  of  lower  point. experimentally the  accessible  time-temperature  which  gum  t h i s method  combined  gels.  provide  viscoelastic with  frequency  superposition  c a n a l s o be u s e d t o  are  result  least  long t i m e s ,  results  limit  at  As d i s c u s s e d b e f o r e ,  over  reliable  logarithmic  which  range  These  only  a  experiments  frequency  out.  As  this  (1980),  of  xanthan-locust this  in  upper  bean  requiring  carried  case  The  xanthan-locust  relaxation  time  60°C.  using  v i s c o e l a s t i c behavior.  be  to  evaluation,  m o l e c u l a r movements or  the  could  the  applied.  were  used  at which  used.  Ferry  absence  pushed  the  at  progres-  frequencies  level  logarithmic  sufficiently  properties  to  by  becomes  limit  spanned  frequency  the  blends,  zone  may h e l p t o  range  two  that  possibly  order  of  lower  instrument  characterize  at  terminal  time  use  gum  out  of  the  it  low  frequency  discussed  intervals  systems.  sufficient  were  systems  at  evaluated  the  experimentally In  data  Thus,  the  liquid,  does  Results information  not from on  extend  the  characterization  is  those  obtained  from  -  dynamic  experiments,  possible  to  gum  gels  apply  at  required. formed  out  the  formed  had  were  gels.  may  bonds  which  difficult  ance  (1980)  are and  to  may  of  the  dissociate  change  actions  come  not  Ferry  bonds  also  of  as  viscoelastic  to  and  different  as  those  Treloar  as  the more  the  (1975)  they  hydrogen  importance  in  may  also  change  Increasing  concentration  can  lead  to  sites  cross-linking.  function  of  The binding  time or temperature experiment  or  formation.  Thus,  the  number  Although  relationship,  provides  other  of  a 1:1  the  no  information residues  stoichiometry  stoichiometrics  strengths  blends  was  the  or  before  early  bonds  in  older  by of  weak  stronger bonds  hydrophobic The  relative  of  the  is  interimport-  favorable  not  only  (Ferry,  out.  junction  It  a  1980).  s i m p l e s t and most ruled  more  stoichiometry in  may  concentration. more  density  on  gel.  progressively  involved  be  are  initially  concentration  i s the  cannot  that  increasing  cross-linking  gels  of  replaced  development  a l s o of  sugar  be  gels.  but  the  that  become  with  are  predominate  bonds  older  bonds  for  and  bean  c a r r i e d out  possible  would  be  used.  of  were  Relative  age,  be  suggested  ages  slowly.  Therefore in  is  may  gels  weak  preparation  tests  which  system  bonds  self-supporting  the  It  It  xanthan-locust  properties  after  equilibrium.  same  to  concentration,  discussed e a r l i e r ,  break. increase  hour  units.  t e s t s cannot  the  formed as  firm,  Cross-linkages  one  common  techniques  the  limitations  system  two  to  polysaccharide  approximately  B e c a u s e of  these  stress relaxation  Nature of  Evaluation  of  total  -  conversion  concentrations  0.4%  creep or  iv)  carried  either  higher At  and  after  74  of zone  likely is  also  -  possible binding  that of  there  the  is  no  exact  et  al.  and  locust  K-carrageenan  has  a minimum  the  of  locust  addition  concentrations  systems, found  the  bean  unit  concluded  that  the  the  alignment model by  of  Such  has  been  Southwick  a  or  even  is  tendency  al.  serve  the  and of  locust  also for  at  of of  had  there  was  onto  that  relatively  total model  not  for  gum  (1984)  the  carrageenan-  pure  carrageenan. They  incorporated  no s u p e r i m p o s i t i o n of  carrageenan, involving was  carrageenan  gum m o l e c u l e s  this  bean al.  been  gum m o l e c u l e s large  et  to  on  polymer  unchanged.  interaction  bean  Pure  However,  Carroll  those  gum  pattern  the  of  they  parallel  unlikely.  A  crystallites  surface  of  the  bean  gum  unreasonable. feasible  xanthan  Norton  a  for  molecules  (Dintzis  as " b r i d g i n g " of  1.5%.  xanthan-locust  essentially  Since  quite  1980;  formation  to  bean  bean  of  patterns  were  locust  documented 1979;  study,  their  molecular  considered  a model  In  of  diffraction.  currently-accepted for  network.  interaction  occurs  proposed  locust  the  fiber  gelation  identical  of  linking  not  repeatedly  in  were  diffraction  a few  was  m o l e c u l e s might resulting  association  concentration  diffraction  specific  the of  The  et  3.  carrageenan  attachment  crystallites  Figure  gel  X-ray  The  dimensions  gum  that  0.5%. that  molecules  using  gum,  fiber  cell  involving  systems.  in  examined  gelling  as  systems  bean  suggested  of  have  gum  bean  same  carrageenan  locust  bean  as  X-ray  gum  Measured  into  low  shown  that  locust  as the  as  stoichiometry  (1984)  ic-carrageenan  is  -  polysaccharides.  Carroll  synergism  75  et  to  aggregate  1970;  al.  1984).  molecules  between  less  et  al.  xanthan-locust  open  Morris  in et  Locust xanthan  three-dimensional  solution al. bean  1977; gum  aggregates network.  - 76 -  The f l e x i b i l i t y of to  act  as  hydrogen well  2.  a  l o c u s t bean gum m o l e c u l e s may f a c i l i t a t e i t s  "cross-linking"  bonding  may  General  flow  xanthan-locust  bean  concentration.  taken  rate  not  shear r a t e , a  well  further  behavior  Rheological  follow  as  together.  at  are  shown  in  Figure  0.2% and 0.05% t o t a l  behavior  fluids  of  with the  corresponded  as i n d i c a t e d  by the  shear  a nearly  Ymax.  This  analyses  to  17,  for  polysaccharthat  negative  of  non-  slopes  path.  rate  Rheological  were  constant  decreasing values  of  collected  shear  stress  data after value  of  shear  obtained  using  the at  samples the  was c o n s i d e r e d an adequate method f o r  condition were  i n c r e a s i n g , then  same  to  defined  The apparent  rheograms  gum s o l u t i o n s  first  values  sheared  aggregates  Samples e x h i b i t e d a l i m i t e d amount of time dependence as  rheograms  decreasing  xanthan  and  Properties  pseudoplastic  the rheograms.  did  interactions  Considerations  Typical  Newtonian  dipole  holding  as b r i d g i n g l o c u s t bean gum m o l e c u l e s  a)  been  Weak  be r e s p o n s i b l e f o r  Steady Shear Flow  ide  agent.  ability  at  the  carried  out  start  of  using  data  v i s c o s i t y , n a t any shear r a t e ,  shear  (Mewis,  obtained  y was  the maximum shear r a t e u s e d , the shear r a t e of measurement t d u r i n g which shear was a p p l i e d .  n  =  f (vY  That i s ,  > y , t) max' *  maximum producing  1979).  in t h i s  then  had  a  All  manner.  function and the  of  time,  -  10  -1  Figure  •  0.2 °to,  O  0.05O/O, H2O  A  02%,  +  0 . 0 5 % , 0.1 M NaCl T  77 -  HaO 0.1 M NaCl  1 1 I III  I  10°  1  1  1 1 I IIII 10  T  1 1 I II I  1  SHEAR RATE ( sr ) 1  17. Rheograms f o r xanthan-locust bean gum solutions at 20°C p l o t t e d according to the power law flow model.  10  2  - 78 -  In more c o m p l i c a t e d  relationships,  structural  parameter,  history  the  of  X which  tion  place result  increased forces  at  the  in  the  weak, to  units  reduced  give  Alignment  of  rigid,  gives  city.  If from  flow the  rise  predominantly shearing giving  to  is  complete  be r e p l a c e d by a  describes  along  the  of  the  recovery shearing  dipole The  to  structural  of  In  of  structure  to  viscosities.  If  steady  to  these  shear  are  viscosities.  planes, shear  are  are  flow  leading  apparent  interactions.  dependent  attrac-  solution  from  lower  especially  thinning is  slow,  and  it  are  long  and  was bean  viscositdependent shown  that  gum  were  easily disrupted  recovered It  original  size  pseudoplasti-  time  locust  behavior.  the  and  section,  These not  or  if  apparent  different  xanthan  interactions  of  and  previous  between  forces  Smaller  structure  the  processes  units.  of  regimes  from  structural  shear  time  recovery  arising  flow  the  arise  in  apparent  forces  phenomenon  interaction weak,  higher  to  effects  particles  associated  observed.  forces. rise  may  Intermolecular  of  and  resistance  rate  of  flow  the  molecules  behavior  level.  association  successive  forces  Ymax  completely  dependent  molecular  disrupt  the  time  hydrodynamic  sufficient  ies  and  r e s i s t a n c e to  are  more  term  material.  Pseudoplastic taking  the  by  instantaneously, is  level  possible does  not  that occur  (rheodestruction). The materials yield  p r e s e n c e of of  this  stresses  specifically  a yield  nature.  of  in this  stress  However,  xanthan-locust study.  is the  bean  a l s o a common c h a r a c t e r i s t i c time gum  dependent  blends  were  properties not  of or  examined  -  In  isolated  cases,  scatter  low shear Newtonian  region.  were  this  available  adequate model  fit  to  was f i t t e d  of  power Table  law 5),  no  of  the  with  the  analysis  interaction  behavior  index  temperature, greater  (p  <  brought  and  in  the  results  in  d e g r e e s of  the  differences were  only  fractional  freedom  an  variables  initial  from  the  these  index  obtained in  two  the  factorial  associated with  the  statistical of  shown  in  gum  in the  in  two  combined  solutions  0.68).  All  were  the in  two  of  which  Appendix  second  II).  experiments of  there  are  the  were  analysis.  in  effects  associated the  while  flow  examined  significant A7  the  correspondin  precision  freedom  experiment error  are  changes  had  (Table  from  degrees  5.  and t h e  effects  factors  _ 1  Table  second . experiment  strength  s  here.  to  significant  50  in  being  bean  0.25  at  performed  analyses  a n a l y s e s shown  ionic  behavior  Differences  There  shown  a n a l y s e s were  ranged  that  flow  analyses.  also  xanthan-locust  indicated the  to  are  The  However,  on  due  an  rheological  viscosity  these  about  0.05).  0.01)  probably  the  c o n c e n t r a t i o n , temperature  concentration  detail,  in  of  values  except  term  a  points  provided  other  for  give the f i n a l  (n  m,  factorial  II.  terms  pseudoplasticity  examined  and  variance  Appendix  e r r o r term to  variables  of  insignificant  considerably  n  fractional  A5 and A6 of  The varied  parameters  Taguchi's  data  of  data.  and  law  of  model  power  steps,  term  the  values  development  a l i m i t e d number  The  A4,  <  the  (r  and  the  Conditions  Tables  (p  to  indicated  Since only  region  data  plots  Flow P r o p e r t i e s Under D i f f e r e n t  Results  ing  the  -  b)  obtained' in  with  in  79  two error forty It  is  - 80 -  Table 5.  Summary of flow parameters (Y = 0.2 - 175 s" ) obtained from Taguchi's fractional factorial experiment.  Expt. No.  m  1  n  mPa s 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27  1  Y  = 50 s ) _ 1  0.493 0.480 0.381 0.642 0.380 0.558 0.416 0.667 0.628 0.683 0.666 0.460 0.592 0.594 0.448 0.278 0.649 0.610 0.538 0.482 0.609 0.246 0.730 0.633 0.484 0.636 0.651  21.4 87.9 125.6 24.2 105.0 33.0 29.3 15.8 12.5 17.7 5.3 16.5 17.7 41.0 24.7 19.7 7.3 4.0 8.1 12.6 2.2 28.5 2.7 11.0 1.7 3.8 4.2  Obtained f r o m p o o l e d r e g r e s s i o n o f 4 s u b - s a m p l e s . Calculated  from  regression  r  2  mPa s  n  200.0 672.0 1414.0 97.9 1188.0 187.0 288.0 58.2 53.5 61.1 19.5 137.0 87.1 200.4 213.9 332.0 28.6 18.5 49.1 95.3 10.0 546.0 7.6 46.2 12.9 16.0 16.4  n(at  parameters.  0.977 0.957 0.973 0.973 0.854 0.602 0.990 0.980 0.932 0.945 0.897 0.968 0.660 0.828 0.952 0.983 0.876 0.917 0.958 0.985 0.856 0.979 0.728 0.887 0.947 0.863 0.907  -  therefore  much  experiment. effects ant flow gum  The  of  in  blends  of  structure  two  18.  n values),  For  with  in  at  0.1  not  for  flow  trends  behavior  M NaCl,  the  also  The  effect  (numerically viscosity  equal  at  strength  there  was  followed  an by  were  and f o r  the  M NaCl, 40°C,  values  saccharide  s"1  also  varied  (Tables  A8  increase  in  the  concentration  of  for  less  on  were  Appendix  with the  and  s  - 1  II).  with  19  the  ),  values  of  These  coefficient  and t h e  apparent  concentration blends  lower  constant  low  decreased  in  For  up t o  for  solutions  NaCl,  decreased  40°C These  concentrations  20).  was  and  water,  up t o  temperature.  and  to  experiment.  temperature  temperature  at  manner.  For  at  rate  and  blends  consistency 1  bean  (decreasing  breakdown  factorial  solutions  remained  M  For  the  strength  concentration  consistent  at  in  ionic  electrolyte,  increasing  (Figures  signific-  concentration,  the  combined  Changes  polysaccharide  coefficient 0.1  the  second  xanthan-locust  structure  viscosity with  decrease  in  for  lower  higher  a  with  viscosity  consistency  of  viscosity  coefficient  usual  the  fractional  decrease  apparent the  and A9  pronounced  consistency the  in  apparent  normal  more  before of  apparent  the  effects  to  shown  by added  at  the  temperature  the  50  ionic  changed  of  0.01).  concentration.  at  i n d i c a t e d by t h e  (p  the  i n c r e a s i n g temperature  rate  while  strength  <  in  that  concentration  solutions higher  index  were  of  stabilized  the  i n c r e a s i n g temperature  the  levels  are  showed  ionic  index  temperature  differences  also  and  increased with  a 40°C  solutions  analysis  behavior  blends  breakdown  concentration  of  flow  -  significant  concentration  different  up t o  for  declare  detailed  the  index  at  Figure  with  more  affecting  behavior  50°C  to  temperature,  in  0.1  easier  81  blends  temperatures  observed. of  in  The  0.05%  poly-  steadily  with  - 82 -  ;  i  0.0  Figure  10.0  18.  1  20.0  1  30.0  1  40.0  TEMPERATURE  1  50.0  (°C)  E f f e c t o f t e m p e r a t u r e on f l o w b e h a v i o r o f x a n t h a n - l o c u s t bean s o l u t i o n s .  1—  60.0  index  - 83 -  c  2 UJ  O  o o — o Ul  >o 2  00 10  z o o  o J  0.0  1  1  1  10.0  20.0  30.0  TEMPERATURE Figure  19.  E f f e c t o f t e m p e r a t u r e on t h e c o e f f i c i e n t of xanthan-locust solutions.  •  0.2 °to,  o  0.050/0, H2O  A  02%,  +  005O/o, 0.1 M NaCl  HaO  0.1 M NaCl  1  40.0  50.0  (°C) consistency bean gum  60.0  - 84 -  •  0.2 °to, HjO  O  0.05 o/b, HaO  A  0.2%,  0.1 M NaCl  +  005%,  O.lMNaCI  O  a.  CO  o  00 2 2 UJ  or <  <  O -  1  0.0  10.0  1  !  I  1  1  20.0  30.0  40.0  50.0  60.0  TEMPERATURE Figure  20.  Effect  (°C)  o f t e m p e r a t u r e on t h e a p p a r e n t  ( Y = 50 s " ) solutions. 1  of  xanthan-locust  viscosity  bean gum  -  temperature.  Apparent  considerably  lower  The under  similar (1961)  to  that  below  solutions  decrease  of  behavior  apparent  on  of  results  i n charge  under in  operation,  bean  i t was shown  the conditions  gum s o l u t i o n s The  presence dependent  on  to  lower  salt  solution is  polysaccharide  u s e d and t h e pH o r d e g r e e ionizable  groups  substitution xanthan tion),  on t h e p o l y m e r  solutions Jeanes  present,  et  above c o n c e n t r a t i o n s maximum  with  viscosities  whereas  at  of  higher  ionic  in  high  increased  compact  ionic  bean  t h e above mentioned  behavior  viscosities  of  the  and S m i t h  concentrations  of  observed  the  gum.  Thus, may be  xanthan-locust  concentration  of  to e f f e c t s  salt.  (1981)  also  viscosity  being of  salt  The number  of  pyruvate  of  polysaccharide  al.  in the  effects  on t h e d e g r e e  (<0.1%  of  In serve  polysaccharide  In a d d i t i o n  et  also  effects  of the p o l y a n i o n .  depends  form.  salt.  xanthan  with  coil  strengths  and l o c u s t  above 0 . 4 % p o l y s a c c h a r i d e ,  increasing  et a l .  which,  molecule.  (1961)  very  salts  a t low c o n c e n t r a t i o n s al.  was  i n the presence of  apparent  turn,  solutions  solutions  ionization  in  gum  salt.  concentration,  of  water.  of  xanthan  complicated,  were  on t h e a d d i t i o n  and a more  both  in  Jeanes  apparent salt  NaCl  increased  that  between here,  of  i n t h e presence of e x t e r n a l  reported of  used  leading  M  strength  solutions.  0.1%,  behavior  screening  interaction  of  addition  xanthan  bean  and i o n i c  xanthan  viscosities  in viscosity  the  of  concentrations  strength  disrupt  xanthan-locust  temperature  polyelectrolyte  to  0.1  of  decreased  section,  in  behavior  normal  previous  solution  o f t h e same c o n c e n t r a t i o n  follows  the  of  solutions  reported  concentrations, The  than  conditions  the  found  xanthan  viscosities  rheological  different  85 -  s a l t on  concentranoted  that  increased to a  Fluctuating  behavior  -  was  observed  that  the  at  changes  xanthan  at  An  viscosity  whereas  In  et  al.  K+  0.31,  salt  The  are  conformation.  that  addition  of  appeared  to  of  xanthan  gum b l e n d s The of  was  if  attributed  situated  near  flow  of  above  the  studies  concentration  of a  and  hydrogen  decrease  solutions  size a  an  of  in the  are to  of  substitution  increase  on t h e  through  of  xanthan  methyl  the  helical  diffusion  coeffi-  of  was  over  (ca. in  the  a wide  by  0.02M  his  suggested  above  whether  filters,  increased  used  suggested that  determine  pyruvate  concentration  concentration  required  macro-  millipore  polysaccharide  (1978)  of  (Smith  in  periphery  based  critical of  pyruvate  to  the  solutions  show s i m i l a r c o m p l i c a t e d  has  in  interactions  (1983),  critical  and M i l as  of  m o l e c u l e s was e s s e n t i a l l y c o n s t a n t  salts  carboxylate  minimized  virtue  for  pyruvate  increasing ionic strength  of  al.  insensitivity  is  purified  of  the  resulted  degree  a result  concentrations  Rinaudo  by  observed  the  was  et  than  s a l t to  When  repulsion  strength  hydrodynamic  Additional  polysaccharide  presence  and  be l e s s  (1961).  10"2M.  as  electrolyte  However,  s i z e of  increase  the  NaCl).  al.  form,  Southwick  degree  the  suggested  form.  suitably  viscosity  suggested  et  reverse  associations,  which  ionic  salt  on  accentuated  v i s c o s i t y increased with  1981).  cients,  in  be  (1980)  of  polyanion.  interchain  even  the  i n the  the  molecular groups  may  increase  polysaccharide  the  Symes  addition  depended  of  protonated,  forces  bonding.  exceeded  ionization  fully  attractive  concentrations.  concentration,  or  are  -  i n s o l u t i o n v i s c o s i t y upon  high  substitution groups  intermediate  86  study  by  Jeanes  hydrodynamic  ionic  range of  strengths salt  xanthan-locust  and bean  behavior.  xanthan  been f r e q u e n t l y  solutions documented  to  temperature  (Whitcomb  and  in  the  Macosko,  -  1978;  Anon.  that  in  absence  in  viscosity  viscosity  with  Jeanes  the  increase  xanthan  1978).  of  with  xanthan  temperature and  1977).  was  only  The l e s s  polysaccharide strengths  associate melting.  concentration,  may  solutions, al.  was  in  apparent  because  the  varied with  addition,  the t r a n s i t i o n temperature than  methods.  However,  viscosity  of  the shear  the melting  xanthan  significant apparent  solutions,  rates  viscosity be  due  A4  that  obtained  it  viscosity  with  determined  conditions  higher  1  of xanthan  b e a n gum a t e q u i v a l e n t  contributions. justified  which  of  the  to  helix maximum  the v i s c o s i t y .  by o t h e r  of  In  experimental  f o r the increase low i o n i c  behavior  Appendix  increased  when  II). the  apparent  s o l u t i o n s were  concentrations.  ionic  in  strength  obvious.  the flow of  was  at 0.2%  the onset  at  decrease  v i s c o m e t r i c a l l y , was o f t e n  In p r e l i m i n a r y e x p e r i m e n t s ,  o f 50 s '  of  blends  was n o t  rationalization  and A6  volume  et a l .  to  of c o u n t e r i o n  i s not immediately  (Tables  in  (Morris  for  used t o e v a l u a t e  (p < 0 . 0 5 ) a f f e c t i n g  apparent  increased.  shear  locust  factor  and  present  temperature,  under  increase  change  i n w h i c h t h e two p o l y s a c c h a r i d e s w e r e m i x e d  viscosity  plasticity xanthan  ratio  in  was  showed  anomalous  viscosity  conformational  viscosity  temperature  an a l t e r n a t i v e  i n c r e a s i n g temperature The  rate  The  Normal  possibly  suggested  appeared,  much l o w e r  the  as a r e s u l t  (1984)  an  i n t h e hydrodynamic  form  increase  increase  This  coil  pronounced  et  the  random  when  showed  temperature.  an i n c r e a s e  observed  the  of these  Launay  to  solutions  increasing  to  and Dea e t a l . ( 1 9 7 7 )  as t h e m o l e c u l e c h a n g e d c o n f o r m a t i o n .  complete  and  -  e t a l . (1961)  salt,  was a t t r i b u t e d  87  index  and t h e  Both  pseudo-  proportion  of  v i s c o s i t i e s (up  higher  Above t h i s  was a l s o a  than shear  those  of  rate the  -  reverse  became  xanthan  solutions.  blends  simply  ride.  because Thus  reflect  of  it  the  of  the  align  in  shear  rates,  system,  solution  apparent  solutions  xanthan  may  viscosities.  At  result  Kovacs  reflected  the  rides.  However,  no  binding  used  exists The  between  flow  range  due  to  that  used, greater  viscosity  the  behavior  gum s o l u t i o n s w e r e pH  This  also  would  fall  pseudoplastic  of  xanthan  shear  rates, of  of  optimal  binding  to of  of  no  under  viscosities  by  the  somewhat  the  pH of  more  apparent for  gel  polysacchaexperimental  stoichiometry  increasing It  pH  of  conditions.  solution.  extreme  low  higher  xanthan-locust  the  to  proportion  two  polysaccharide.  if  had  ratio  these  of  increase with the  the  exact  At  lower  gum  under  polysaccharides and  1980).  progressively  the  tendency  i n c r e a s i n g the  that  solubilization  the  proportion  suggests  tended  polysaccha-  higher  influenced  viscosity  xanthan  al.  observed  index  of  have a g r e a t e r  was  two  properties  et  stoichiometry  here.  of  Southwick  suggested  optimum  of  increased  molecules  solutions  (1973)  solution  nature  1977;  higher in  strengths  conditions  a  that  xanthan  al.  pseudoplastic  properties  as x a n t h a n  with  viscosities.  of  et  greater  possible  solution  (Morris  -  the  is  Increased • proportions  character  of  true,  88  bean  Over  the  pH  possibly  is  expected  conditions  were  used. The were  viscoelastic  considerably  used,  4M u r e a  shear  flow  possible were  not  was  affected not  viscosity  that  properties  either  sufficient  a of  by  of  xanthan-locust  8 M urea.  significant  However,  factor  xanthan-locust  the  concentration  to  bring  about  (p  a  under  > 0.05)  bean of  bean  urea marked  gum or  gum the  solutions conditions  affecting  solutions. the  change  It  conditions in  steady is used  viscosity.  - 89 -  Alternatively,  a balance  (1) i n c r e a s e d v i s c o s i t y the of  polysaccharides, h y d r o g e n bonds  and  in the  may due  h a v e been to  the  achieved  greater  (2) d e c r e a s e d interacting  i n two  ability  viscosity  system.  as  of  opposing  forces:  urea  to  solubilize  result  of  disruption  -  90  -  CONCLUSIONS  The gum  and  exist  blends  between  locust are  viscoelastic  bean  very  gum.  at  the  xanthan  These  entanglements lightly  M  intermolecular exist  the  gelling  system,  the The at  forces  results 0.4%  Under c o n d i t i o n s  behave  of  and s t e a d y  dynamic  order-disorder ordered  is  typical of  of  of  xanthan  between  number  and  xanthan with  highly  greater  more  the  entangled  magnitude and  properties  solutions  8 M urea,  than  locust  specific  viscoelastic  between  suggest  that  concentration, for  than  bean simple  typical  of  low  ionic  with  shear  transition  experiments of  xanthan  stabilized  only  a  by  high  formation  of  network. limited  are  and to the the  Hydrogen  roles. bean  gum  i n c r e a s i n g temperature  and  xanthan-locust  60°C.  suggest occur  M KC1  interactions  the  strengths,  0.6  polysaccharides  in the  dipole  i n t e r a c t i o n s may p l a y of  two  early  stabilizing  s o l i d - l i k e behavior  is  of the  as v i s c o e l a s t i c l i q u i d s a t  conformation  in  greater,  considered  interactions  and h y d r o p h o b i c  eventually  low  are considerably  molecules  aqueous  responsible  lose their  association  associations are  bean  network.  treatments,  extents.  solutions  between  of  between  associations  system  give  The  locust  associations  behavior  and  varying  bonding  solution  xanthan, levels  concentration  intermolecular  are  reduce  principal  0.4%  of  various  solution.  same c o n c e n t r a t i o n ,  cross-linked  KOH  at  solutions that  in  associations  Solvent 1  The  of  indicate  polysaccarides  xanthan  Strong  in  two  gum m o l e c u l e s  that  systems. those  the  the  weak.  molecules, result  of  properties  The  that  gel  combined melting  simultaneously. ionic  results  strengths,  and When  the  the the  inter-  -  acting  system m a i n t a i n s  stable  at  the  temperature  interactions dimensional In is  ionic  a  steady  tional  xanthan.  change of  xanthan-guar  xanthan  and  The  appeared  to  increase  behavior  of  conditions stabilization  shear  is  of  with  of  the  in  shear  three  viscosity  optical  to the  rotation  et  al.  xanthan  is  still  1977), in  pH  of  low  rheological conforma-  low i o n i c s t r e n g t h  (Dea  and  ele-  studies the  of  order-  evidence  for  study.  bean gum s o l u t i o n s i n c r e a s e d w i t h Temperature  strength the  strength,  the  of  increase  has been a t t r i b u t e d  of  the  solutions  pH  and  gum  effects  solution. and  the  ratio  were  Viscosity  proportion  of  affected  the  all  bean gum s o l u t i o n s . studies  indicate  interactions  i n t e r a c t i n g system. with  more  hydrophobic  a s shown v i s c o m e t r i c a l l y , i n t h i s  ionic  the  become  that  steady  concentration.  dipole  properties by t h e  reported  xanthan-locust  the  to  formation  anomalous  solutions  viscoelastic  the  consistent  flow  dominated  of  to  transition  Ionic  used,  the  an  as o b s e r v e d  xanthan-locust of  possible  under c o n d i t i o n s of  as  increased.  •Results  this  on  in  is  appears  b e a n gum s o l u t i o n s u n d e r c o n d i t i o n s o f  behavior  polysaccharide  dependent  It  role  studies  bean gum b l e n d s ,  strongly  C.  even  under t h e s e c o n d i t i o n s .  xanthan-tara  v i s c o s i t y of  increasing  60°  similar  Thus,  conformational  xanthan-locust  flow  is This  temperatures.  xanthan  flow  in xanthan-locust  of  disorder  of  structure  This  -  e l a s t i c i t y and  dominant  shear  strength.  behavior  vated  play network  observed  its  91  s o l u t i o n p r o p e r t i e s of  be  These f o r c e s  observation  xanthan-locust  may  that,  that bean  both  under  the  responsible  for  a r e v e r y weak  and  dynamic  and  gum s o l u t i o n s a p p e a r  xanthan.  steady to  be  -  92 -  REFERENCES AOAC. 1980. 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Chichester,  1980. England.  C.W.  Rheological  p o l y s a c c h a r i d e s and t h e i r 117: 2 4 2 . 1978.  Rheology  Techniques.  behavior  of  xanthan.  J.  Ellis  Horwood  Ltd.  -  APPENDIX I.  In to  Basic v i s c o e l a s t i c  small  amplitude  Y  1 S  0  amplitude  shear,  The  the  material  is  s t r a i n , as a f u n c t i o n  subjected  of  time  can  by  strain  t n e  is  theory.  strain.  Y  where  -  oscillatory  a sinusoidally varying  be r e p r e s e n t e d  98  =  Y  amplitude  s u f f i c i e n t l y small  [Al]  c o s u>t  0  the  (Whorlow, resultant  1980).  If  the  s t r e s s c a n be  strain  represented  by  Q  cos  (cot + 6)  of  the  shear  a = a  where  o0  is  the  of  the  stress  is  independent  amplitude  relative of Y  0  to  t n u s  ^  Y0  phase of  sufficiently  1 s  shift  small  6 are  amplitude  strain.  s t r e s s and The  E q u a t i o n A2 can be  = ^ 0  If  the  T  [A2]  6 i s the  dependence  of  phase a/y  on  0  [A3]  c o s (u>t + 6)  independent  of  oscillatory  the  amplitude  amplitude. shear  tests  time  rewritten  o  small,  shift  ratio  This can  0  0  means t h a t  be  and  (a /y ) the  completely  the  results  described  -  by  plots  of  However i t  (O /YO)  and  0  storage  (G'  a  a ratio measure  The l o s s  of  the  stress in  of  energy  stored  the  the  ratio  strain.  stress ideal  It  of is  the  of  e q u a t i o n A2  c o s wt -  G"  frequency i n the  (Dealy,  1982).  form  [A4)  s i n wt)  a cos 6 =-2— T o  [A5]  phase w i t h  the  s t r a i n to  e l a s t i c a l l y during  a  the  cycle  strain. of  It  is  deformation.  elastic are  stress  i n phase  (Hookean)  90°  out  introduced  into  the  portion  the material  of  a sin 6 = -°— T o  of  out  the  energy  (G"  material. phase  system  is  [A6]  90°  a measure of  and s t r a i n a r e  strain  functions  modulus  G"  gives  -  modulus  G'  is  as  i s customary t o w r i t e  a = Yq  The  6  99  and  = 0), If  G'  one  dissipated  response.  of  phase  the  strain  d i s s i p a t e d as h e a t .  material = 0 but finds as  with  behavior G"  that heat.  If  i s that  of  stress  to the an  *  0 the  and  all  of  the  energy  This  is  the  viscous  -  The  ratio  the r a t i o If  of energy  [A7]  d i s s i p a t e d , t o the energy  stored.  u s e i s made o f t h e r e l a t i o n s h i p  oot =  E q u a t i o n A l and E q u a t i o n A2 c a n be  Y -  R (Y0 e  a = R (a e i ^ 6 , t + 6 ) ) \ Q  It  is  convenient  The  complex modulus  to G  G*  refer  shear  rate  to  i w t  ela)t  rewritten  )  CA8]  = R (a  e  1 6  eia)t)  [A9]  o  o0el5  as  the  complex  amplitude  of  a  * .  i s d e f i n e d as  = complex ~ complex  a e - ° o  The  tangent  6= ^  c o s tot + i s i n  then  -  o f t h e two m o d u l i , t h e l o s s  tan  is  100  stress strain  amplitude amplitude  1 6  = G'  + 1G"  i s a l s o p e r i o d i c and i s g i v e n  [A10]  by  -  Y  so t h a t  =  E q u a t i o n A4 may be w r i t t e n  a = y  (-  n'  where  = G'/w  The  function  stress  in  phase w i t h  stress  90°  strain.  of  n1  steady  flow  wt)  CA12]  =  CA14]  0  (a0/"Y0)  rate  or  cos  TI"  form  [A13]  phase w i t h  in-phase  another  = (° /v ) s i n 6  i s the  the  [All]  COS  dynamic of  viscosity  strain  the  real  6  rate  to of  component  viscosity  n0  as  rate strain n'  the  for  and of  i s the strain  divided a  ratio and  n"  by t h e  the  is  the  rate  viscoelastic  frequency  of  of  liquid  w approaches  zero  1980). The  complex  out  The  approaches (Ferry,  wt +  sin  wt  sin  in yet  0  II  -  wt = -y  sin  -UY_  101  phase  relationships  viscosity n*,  can  also  be  expressed  in  terms  of  a  where  n  *  = n  ,  II  - i n  [A15]  -  APPENDIX I I .  Table  Al.  Analyses  102 -  of v a r i a n c e f o r r h e o l o g i c a l  Summary o f F - r a t i o s o b t a i n e d f r o m s p l i t - p l o t d e s i g n f o r dynamic s t o r a g e m o d u l u s .  Frequency Source  Run Temperature Run  parameters.  x Temp  experimental  s'  : 0.60  1.90  0 . 4 8 NS  0.02  167.15** 1.39  NS  6.0  19.0  60.0  NS  0 . 8 6 NS  3.31*  1159.**  191.6**  318.44**  292.26**  0.41  0 . 5 0 NS  3.99*  4.18*  NS  2.27  NS  Sol vent  16.71**  23.92**  87.05**  71.13**  81.43**  Sol  x Run  1.34  NS  1 . 9 7 NS  1.05  1.08  0 . 9 8 NS  Sol  x Temp  68.06**  21.02**  14.94**  6.16*  6.82*  Sol  x Run x Temp  0.67  1.74  13.06*  3.94**  5.12**  NS = Not s i g n i f i c a n t * **  (p >  NS  0.05);  = s i g n i f i c a n t at 0.01 < p < 0 . 0 5 ; = s i g n i f i c a n t at p < 0 . 0 1 .  NS  NS  NS  -  T a b l e A2.  Summary o f F - r a t i o s design f o r the l o s s  103  -  o b t a i n e d from modulus.  split-plot  Frequency s " 0.60 Run  0.89  NS  42.48*  Temperature Run  1.90  x Temp  5.07*  0.24  6.0 NS  225.62** 1.16  NS  Sol vent  16.16**  Sol  x Run  2.63  NS  0.46  Sol  x Temp  3.96  NS  12.01**  Sol  x Run x Temp  2.50*  NS = Not s i g n i f i c a n t  (p >  108.09**  1.70  0.05);  *  = significant  at 0.01 < p < 0 . 0 5 ;  **  = significant  at p < 0 . 0 1 .  NS  NS  2.65  experimental  1  19.0 NS  362.03**  6.71**  60.0 2.87  NS  43.89**  60.51*  6.45**  3.69*  126.33**  80.14**  20.80**  0.66  1 . 2 9 NS  3.28**  16.42**  21.61**  21.97**  13.02*  3.28**  4.17**  1 . 2 6 NS  NS  -  104  -  Table A3. Summary o f F - r a t i o s o b t a i n e d f r o m s p l i t - p l o t design f o r the loss  experimental  tangent.  Frequency s "  1  Source 0.60 Run  1.42  Temperature Run  x Temp  1.90 NS  44.19* 0.61*  0.27  NS  732.33** 0.11  NS  Sol vent  36.17**  29.55**  Sol  x Run  1.09  1.54  Sol  x Temp  Sol  x Run x Temp  NS = Not  NS  112.06** 0.75  NS  s i g n i f i c a n t (p >  0.05);  < p < 0.05;  *  = significant  at 0.01  **  = significant  at p < 0 . 0 1 .  NS  55.87** 1.11  19.0  60.0  NS  6.71**  2 . 8 8 NS  1767.4**  43.89**  60.51*  NS  6.44**  3.69*  102.46**  80.14**  20.80**  6.0  NS  0.42  0.14  1.05  NS  NS  3.27**  244.47**  21.61**  21.97**  0 . 5 9 NS  3.28**  4.17**  1.29  -  Table  105  -  A n a l y s i s of v a r i a n c e f o r f l o w b e h a v i o r index n , from T a g u c h i ' s F r a c t i o n a l F a c t o r i a l E x p e r i m e n t L 7 (3 ).  A4.  2  Ionic  df1  MS  F-ratio  2  0.02390  9.51*  2  0.02370  9.43*  2  0.03200  12.72*  2  0.02072  8.24*  Strength  pH Gum  Ratio  Urea Cone  x Temp.  4  0.00906  3.60NS  Cone  x  I.S.  4  0.01621  6.45*  Temp x  I.S.  4  0.02396  9.53**  6  0.02515  Error1  26  Total  df f o r c o n c e n t r a t i o n and t e m p e r a t u r e p o o l e d w i t h e r r o r t e r m s were not s i g n i f i c a n t i n o r i g i n a l a n a l y s i s of v a r i a n c e .  l  NS = n o t  s i g n i f i c a n t (P > 0 . 0 5 ) ;  *  = s i g n i f i c a n t at  0.01  **  = s i g n i f i c a n t at  p <  < p < 0.05; 0.01.  as  they  -  Table  A5.  106  -  A n a l y s i s o f v a r i a n c e f o r c o n s i s t e n c y c o e f f i c i e n t m, f r o m T a g u c h i ' s F r a c t i o n a l F a c t o r i a l E x p e r i m e n t L 7 (3 ). 2  df1  MS  F-ratio  Concentration  2  1.8850  36.53**  Temperature  2  0.6860  13.29**  pH  2  0.4616  8.94*  2  1.1102  21.51**  Gum  Ratio  Cone  x Temp.  4  0.1556  3.02NS  Cone  x  I.S.  4  0.1610  3.12NS  Temp x  I.S.  4  0.1307  2.53NS  6  0.0516  Error1 Total  26  df f o r i o n i c s t r e n g t h and u r e a p o o l e d w i t h e r r o r s i g n i f i c a n t i n o r i g i n a l a n a l y s i s of v a r i a n c e . NS = n o t s i g n i f i c a n t  (p >  0.05);  *  = s i g n i f i c a n t at 0.01  < p < 0.05;  **  = s i g n i f i c a n t at p < 0 . 0 1 .  terms  as t h e y  were  not  -  Table  A6.  Analysis o f 50 s 13 L27  107  -  of v a r i a n c e f o r v i s c o s i t y obtained at a shear rate from T a g u c h i ' s F r a c t i o n a l F a c t o r i a l Experiment  O ).  df1  MS  F-ratio  Concentration  2  1.4944  121.72**  Temperature  2  0.4954  40.35**  pH  2  0.1807  14.71**  2  0.5880  47.89**  Cone x Temp.  4  0.0853  6.95*  Cone x  I.S.  4  0.0491  4.00NS  Temp x  I.S.  4  0.0117  0.95NS  6  0.0123  Gum  Ratio  Error1 Total  1  26  df f o r i o n i c s t r e n g t h and u r e a p o o l e d w i t h e r r o r s i g n i f i c a n t i n o r i g i n a l a n a l y s i s of v a r i a n c e .  NS = n o t s i g n i f i c a n t  (p >  0.05);  *  = s i g n i f i c a n t at 0.01 < p < 0 . 0 5 ;  **  = s i g n i f i c a n t at p < 0 . 0 1 .  terms  as t h e y  were not  -  Table A 7 .  108  -  A n a l y s i s of v a r i a n c e f o r f l o w b e h a v i o r shear-temperature studies.  df  Source  Mean  index from  Square  steady  F-ratio  Temperature  4  0.01652  8.90**  Ionic  1  0.22861  123.13**  Concentration  1  0.04772  25.70**  I.S.  1  0.04987  26.86**'  I.S.  4  0.05866  31.59**  Temp x Cone  4  0.04924  265.24**  4  0.00911  4.90**  Residual  40  0.00187  Total  59  NS = n o t s i g n i f i c a n t ( p >  0.05);  Strength  x Cone.  Temp x  Temp x Cone x  *  I.S.  = s i g n i f i c a n t at  0.01 < p < 0 . 0 5 ;  = s i g n i f i c a n t at p < 0 . 0 1 .  -  Table  A8.  109  -  A n a l y s i s of v a r i a n c e f o r c o n s i s t e n c y c o e f f i c i e n t from shear-temperature studies.  df  Source  Mean  Square  1.5823  steady  F-ratio 96.97**  Temperature  4  Ionic  1  11.203  686.54**  Concentration  1  25.127  1,539.83**  I.S.  Cone.  1  0.1108  6.79**  I.S.  4  0.2376  14.51**  Temp x Cone  4  0.0118  0 . 7 2 NS  4  0.0578  3.54*  Residual  40  0.0163  Total  59  Strength  x  Temp x  Temp x Cone  x  I.S.  NS = n o t s i g n i f i c a n t  (p >  0.05);  *  = s i g n i f i c a n t at 0.01  < p < 0.05;  **  = s i g n i f i c a n t at P < 0 . 0 1 .  -  110  -  Table A9. A n a l y s i s o f v a r i a n c e f o r v i s c o s i t y a t 50 s " shear-temperature  from  steady  studies.  df  Source  1  Mean  Square  F-ratio  Temperature  4  1.3247  80.39**  Ionic  1  6.4248  389.90**  Strength  1  I.S.  Cone.  1  0.5074  30.79**  Temp x  I.S.  4  0.3324  20.17**  Temp x  Cone  4  0.1568  9.51**  4  0.1413  8.58*  Residual  40  0.0165  Total  59  x  Temp x Cone  x  I.S.  NS = n o t s i g n i f i c a n t  (p >  0.05);  *  = s i g n i f i c a n t at 0 . 0 1 < p < 0 . 0 5 ;  **  = s i g n i f i c a n t at p < 0 . 0 1 .  21.544  1,307.44**  Concentration  


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