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UBC Theses and Dissertations

Some aspects of an investigation of the food value of British Columbia apples Wilkinson, Barclay Robert 1947

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3 3 7 /f*& A 4-Ch/°< / SOME ASPECTS OP AH INVESTIGATION OP THE FOOD VALUE OF BRITISH COLUMBIA APPLES  by Barclay Robert Wilkinson, B.S.A. A Thesis Submitted i n Partial Fulfilment of the Requirements for the Degree of MASTER OF SCIENCE IN AGRICULTURE in Plant Nutrition • i n the Department of Horticulture Approved: (Major) (Minor) The University of British Columbia October, 1947. SOME ASPECTS OF AN•INVESTSGATIOH OEiiTHB FOOD VALUE OF BRITISH COLUMBIA APPLES by Barclay Robert Wilkinson,B.S.A. ABSTRACT The primary objective of the project was to obtstin definite information about the food value of British Columbia apples whichcould be used to advertise the product on the world markets.The f i r s t phase of the work involved activity cage measurements made with mature rats fed a. basic ration,supplemented in the case of some, with fresh apple.The female rats of the apple-fed group showed a remarkable stimulation of physical activity. Xhey also showed an increased respiration rate and a greater degree of reproductivity.A group of young growing rats was fed the basic ration snd another group received this ration plus an apple supplement.lt was shown by per-iodic weighings,that the apple-fed rats made more rapid growth than did the controls.The possibility of these results being brought about by an increased level of riboflavin was discussed,andaanexperiment set up to determine the effects of a pure riboflavin supplement on the activity of rats.The results of this experiment were very similar to those obtained with an apple supplement,although not so strikingly significant.Finally,it was shown by means of a m i c r o b i o l o g i c a l assay, that f r e s h apples contained s u f f i c i e n t r i b o f l a v i n to n e u t r a l i z e e f f e c t i v e l y a d e f i c i e n c y of t h a t v i t a m i n , i f i n c l u d e d i n the d i e t i n a p p r e c i a b l e q u a n t i t i e s . P r o f e s s o r and Department of Head, H o r t i c u l t ure. ACIOTOTOEDGMENT 'The writer wishes to express his sincere gratitude to those whose advice and suggestions made this work possible. Especial thanks are due to Dr. G. H. Harris, Professor of Horticulture (Plant Nutrition), The University of British Columbia, under whose direction the investigation was carried out. Sincere thanks are also due. to Dr. A. F. Barss, Professor and Head of the Department of Horticulture, The University of B r i t i s h Columbia, for his helpful advice and encouragement throughout the period when the problem was under investigation. TABLE OP CONTENTS Page 1. INTRODUCTION (a) General 1 (b) Reason for Experiment 2 •(c) Plan of Experiment . 3 ' 2. MATERIALS AND METHODS (a) Experiment I" 4 (b) Experiment I I . 6 (c) Experiment I I I 8 (d) Experiment IV 8 3. EXPERIMENTAL- RESULTS (a) . Experiment I results 9 (b) Experiment I I results 11 (c) Experiment I I I results 18 (d) Experiment IV results 20 4.f DISCUSSION OF RESULTS . 25 -5. CONCLUSION 31 6. SUMMARY - 32 7 . REFERENCES SOME ASPECTS OP AN INVESTIGATION OP THE POOD VALUE OF BRITISH COLUMBIA APPLES INTRODUCTION British Columbia fruits and vegetables are of a quality-unexcelled throughout the world. Despite this fact, there have been times in the past, and presumably there will be times in the future, when the supply of these products greatly exceeds their demand. While It is true that this reduced demand is due primarily to economic conditions, it is possible to bring about a marked increase in the sales of these commodities on the world markets even in times of depression, provided that a determined effort is made by those connected with the industry to keep the price within the limits that the consumer: can afford to pay, and to make their product as attractive and desirable as possible. Improved cultural methods and fertilizing practices tend to improve the quality and food value of fruit produced, and investigations carried out with this purpose in mind are numerous. In order to improve the food value of any agricultural product considerable information must be available with regard to its chemical composition, particularly its more prominent nutritional qualities, as these will be stressed in any future experimental work. In recent years advertising campaigns have played an increasingly important role in the advancement of sales of agricultural products. It is interesting to note that almost all of these campaigns are built up around some one outstanding characteristic of the product in question. The orange growers, for example, have stressed the com-paratively high Vitamin C content of their product, while some breakfast cereals, such as oatmeal, wheat germ meal, etc., have based their campaigns on the Vitamin content of their product. Dairy products such as milk, butter and cheese have been advertised as essential sources of calcium, Vitamin A and, in the case of irradiated products, as a source of Vitamin D. In some cases vitamins have actually been added to products in order that they may be advertised and sold as containing a definite minimum quantity of the vitamin involved. This, of course, can only be done with processed food materials. These "fortified" products must necessarily sell at a higher price than the natural product, and what is more important, they do not have the same appeal to the prospective buyer. It is, therefore, more desirable to market food products as they are produced, without the addition of any supplementary materials, basing any advertising on the natural attributes of the products. The B. C. Research Council project on "Food Values of B. C. Apples" was°xr.fj?fi^t^ecause it was felt that definite information on this subject, which could be used as a basis for future crop improvement research, and to advertise the product on the world markets, was lacking. A search was therefore begun for evidence to show that apples make a desirable contribution to the diet, which may be regarded as characteristic of this fruit. . 3 . The work described herein was carried on for the B. C. Research Council in connection with the project. It was intended that this work would bring to light any effects which a dietary supplement of apple might have on a group of laboratory white rats (Mus Uorvegicus albinus). Experiments were planned involving' measurements of physical activity, of respiration rate, reproductive capacity and growth rate, on rats fed an apple supplemented diet as compared to those receiving no apple. Provided that an effect was noted, tests were to be made for the purpose of identifying the nutritional factor responsible. This necessitated more feeding experiments involving supplements of any nutritional factor which might reasonably be suspected capable of bringing about the effects, and the elimination of those shown to be not involved. In the work described, the riboflavin content of apples and its effect on the indices previously discussed was stressed. 4. MATERIALS AND METHODS Experiment I Two groups of mature rats were placed i n wire cages. Each group consisted of one male and two females. Prior to the experiment the rats had been fed solely on Purina Laboratory Chow (±) ad libitum since weaning at the age of twenty-one days. Throughout the experi-mental period of 110 days, one group received the basic ration o f Laboratory Chow as before, while the other group received this same ration supplemented with fresh apple at the rate of approximately fifteen per cent of the chow consumed. On these two groups of rats information was collected on the physical activity of each using an "activity cage" with a revolving wire mesh drum equipped with a revolution counter, and a small square wire cage from which the rat had free access to the revolving drum (see Plate I ) . Each rat was placed in the activity cage, supplied with food and water, and allowed to remain there: for t a twenty-four hour period, after which time the number of revolutions the drum had made was recorded and the rat removed. The tests were made i n a definite sequence so that the control male immediately followed the apple-fed male, control female N o . 3 followed apple-fed female No . 1, and control female N o . 4 followed apple-fed female N o . 2 . This was done i n order that each set of activity measurements would be taken under conditions as nearly constant as possible, and so that the time difference between measurements within the same set would be kept constant. PLATE I. ACTIVITY CAGE As an indication of chemical activity within the "body of the rats, that i s , the rate of metabolism, respiration tests were carried out. The procedure used was as follows: The rats were placed, one at a time, i n a wire basket i n a large desiccator. The cover of the desiccator was fit t e d with a rubber stopper and a glass tube to which was attached a length of rubber hose for extracting samples of a i r . The hose was sealed with a screw clamp and the rat l e f t i n the desiccator for a measured period of time of one half hour, which was found to be the longest period that the rats could remain normally active in the closed container without a fresh supply of ai r . A sample of the air within the container was then drawn off with a gas analyser (Orsat apparatus) and tested for carbon dioxide content (see Plate II). A sample of the air in.the laboratory at the time of the experiment was also tested for carbon dioxide content. On these same groups of rats records were kept of the litte r s ' and the dates of arrival. Experiment I I ' Twenty rats, a l l one month old, from four different l i t t e r s , were formed into four groups. The members of each group were selected at random. A l l rats received fresh water at w i l l . Of the four groups one received a basic ration of Buckerfield's dog meal, while another received the same ration supplemented with fifteen per cent of fresh apple. The other two groups were involved i n a Vitamin E test, and for the purposes of this paper w i l l not be discussed. Records were made twice every week of the weights of the rats of each group. P L A T E I I . APPARATUS FOR RESPIRATION TEST 8. Experiment III Two pairs of mat-ore female rats were placed in wire cages and fed the basic ration of laboratory chow pellets, ad libitum. One pair of rats received a supplement of pure riboflavin in solution in the drinking water at a concentration of 20 parts per million, resulting in a daily riboflavin intake of approximately one milligram, while the others received pure water. Activity measurements were made as before, over twenty-four hour periods, but as another activity cage was now available, two rats (one from each group) were tested simultaneously. Experiment IT Samples of fresh apple were analysed for their riboflavin content by the microbiological method of Snell and Strong(2) & (3). This method involves the growing of culturesof Lactobacillus casei in culture media containing definite levels of riboflavin, and titrating the acid produced with standard NaOH. Prom this data, growth curves are produced, which are used in comparison with titration results from similar cultures supplemented with various amounts of HCl extract of riboflavin from the material under test. EXPERIMENTAL RESULTS In the following pages of tables will be found the data obtained from the work described in the preceding section. Table I shows the chemical composition of the two food materials used in the feeding of all the rats involved in the experi-ment. This table also shows the composition of the apple used to supplement the basic rations. Columns 4 and 5 show the percentage composition of the apple supplemented rations. These figures were calculated from the data presented in the first three columns of the table. They serve to show the effect of the apple supplement on the level of the common nutrients which the test rats received. As will be seen from inspection of the table the per cent total sugars is slightly increased, while the per cent starch is decreased considerably,. This results in a lower level of total .carbohydrates. All other nutrient levels are somewhat reduced. Table II shows the physical activity measurements made on the rats fed with laboratory chow pellets, one group receiving an apple supplement. It will be seen that the apple-fed male showed less activity than did the control male. The apple-fed females, on the other hand, showed a tremendously increased physical activity. These effects are made more evident by the accompanying chart, which gives a graphic comparison between the activities of the apple-fed and control rats. TABLE I CHEMICAL COMPOSITION OF FOOD MATERIALS USED IN FEEDING EXPERIMENTS " Per cent Per cent Per cent Per cent Per cent Per cent Total Per cent Per cent Foodstuff Water Dry Wt, Ash Protein Fat Sugars Starch Roughage 1. Apple 84.9$ 15.1$ 0.347$ -.0.189$ 0.4 $(b) 8.61$ .818$ 2,33$ 2. Purina Labora- 8.90 91.1 6.49 ;26.18 5.35 48.46$ 4.62 tory Chow'(a) 3. Dog meal 17.44 82.56 5.284 17.025 5.0 (c) 7.43 32.25 9.82 4. Laboratory Chow plus 15$ apple 20.31 78.20 5.567 22.28 5.15 42.60$ 4.28 5. Dog meal plus 15$ apple 26.56 72.35 4.492 14.498 3.310 7.61 27.533 8.7.0 (a) From "Care and Feeding of Laboratory Animals", Research Laboratories, Ralston Purina Co. (b) From H. J. Heinz Co., Research Department, "Nutritional Charts" (c) From Statement of Contents on Sack, BuckerfielcFs Limited. O 11. Another interesting feature of this experiment is the fact that during the test period, both apple-fed females produced litters of young while the control females produced none. Table III gives the results of the respiration tests described previously. On referring to the table it will be seen that very little difference occurred between the metabolism rates of the male rats whether fed the basic ration, or the apple supplemented ration. In the case of the female rats, apple-fed female Ho. 1 showed no difference in metabolism rate to that of the corresponding control female Ho. 3, and in one test showed a lower rate. Apple-fed female No. 2, on the other hand, showed a greater metabolic rate, in two tests, than did the control female No. 4. The average rate of metabolism of the apple-fed females, -however, was shown to be higher than that of the control females by 12.5 per cent. In Table IV will be found the weights of the young rats so used for Experiment II. This data was treatedAas to express the weight of each rat as a percentage of its original body weight, at each time of weighing. Thus the weight gains were kept on a constant basis, enabling comparisons to be made much more readily. It will be seen that both the control and the apple-fed rats made satisfactory growth,'but that the growth rates of the apple-fed rats were slightly faster in all cases ,and the weights of these at the final weighing were greater in every case than were those of the control rats. This occurred with both male and female rats. TABLE II ACTIVITY TESTS NUMBER OF DRUM REVOLUTIONS PER 24 HOUR PERIOD Test No. _U 2j_ 3^ 4." 5. 6. 7. 8. 9^ 10^ 11^ 12^ 13^ 14^ 15^ 16^ Average Cage 1 ( Male 1 247 46 93 - 154 20 33 17 53 20 21 4 3 1 0 - 51 ( Apple ( Fern. 1 423 613 994 - - Litter 924 868 1059 770 1663 3396 1815 103 1253 - 1157 Supple-( of 7 raent ( Fem. 2 620 927 829 836 Lit t e r - 983 1629 696 1543 1380 975 861 1000 794 - 1006 of 8 Cage 2 ( Male 2 133 154 99 - 114 159 155 134 181 1678 122 88 93 101 54 103 225 ( Control( Fem. 3 52 25 594 - 18 86 49 60 50 147 64 Died - 115 ( ( Fem. 4 17 0 1 0 - - 98 461 290 300 629 386 114 338 514 - 242 Comparative Activities of Hats Fed A p p l e Supplemented, and Basic Rations. Scale- £inch=10Q revolutions in 24 hours. i CO la V) K 3 i t TABLE III RESPIRATION TESTS Expressed as Grams of GOp Liberated per 200 grams of Rat 1. 2. • 3. Average APPLE Female 1 Female 2 Male 1 .034 gm. .046 gm. .026 gm. ,030 gm.. ,032 gm. ,026 gm. .036 gm. .033 gm. ) ) .036 .039 gm. ) .026 gm. Female 3 CONTROL Female 4 Male 2 .034 gm. .026 gm. .028 gm. .034 gm. ,030 gm. ,026 gm. .036 gm. .035 gm. ) ) .032 .028 gm. ) .027 gm. TABLE IV Y/EIGHT GAINS OF BATS, EXPRESSED AS PERCENT OF ORIGINAL WEIGHT Rat Number Day Day Day Day Day Day 7 12 15 19 22 26 Day Day Day Day Day Day 29 33 36 40 48 55 1. Male 19.4 26.8 46.3 75.1 2. Male 22.4 32.9 51.3 86.8 3. Female 23.4 38.9 61.0 81.8 4. Male 23.9 44.6 70.7 91.3 5. Female 30.8 37.2 69.2 94.9 1. Female 18.3 37.5 55.0 86.7 2. Male 14.6 21.4 55.3 88.4 3. Female 17.1 19.5 43.9 80.5 4. Female 15.0 27.5 52.5 87.5 5. Female 17.1 33.3 61.6 102.6 Male - Average 21.9 34.8' 56.1 84.4 Female - Average 27.1 38.1 65.1 88.4 74.6 81.6 76.4 92.4 91.7 101.5 125.4 134.3 146.3 155.2 197.0 235.9 100.0 128.9 139.5, 152.6 163.2 211.8 244.7 110.4 133.8 155.8.162.3 148.1 163.6 192.2 108.7 123.9 141.3 145.7 159.8 191.3 228.3 138.5 165.4 169.2 201.3 189.7 206^4 229.5 122.5 121.7 134.2 149.2 164.2 160.8 243.3 147.6 136.9 202.9 226.2 250.5 228.2 253.4 140.9 170.8 180.5 206.1 234.1 208.5 255^0 142.5 170.0 172.5 183.8 210.0 211.3 238.5 167.9 207;7 205.1 209.0 221.8 228.2 280.8 BISCUIT (Control) APPLE ) BISCUIT Male - Average 14.6 21.4 55.3 88.4 109.7 147.6 136.9 202.9 226.2 250.5 228.2 253?4 ) ) APPLE Female - Average 16.9 29.5 53.3 89.3 108.1 143.5 167.6 173.1 187.0 207.5 202.2 254.4 • ) i—1 o n * •FI C U R E Z, Apple-fed male Apple-fed female B a s i c male B a s i c female TABLE V 17. ACTIVITY TESTS BASIC RIBOFLAVIN SUPPLEMENT No. of Drum Revolutions No. of Drum Revolutions Test Rat per Test Rat per No. No. 24 Hour Period No. No. ' 24 Hour Period 1 1 1885 ) Total Av. 2414 1 3) 2359)Tot. Av. 1859 1 2 888 ) Rat 1 3398 1 4)N0 1509)Rat 3 2207 2 1 4911 ) Rat 2 1430 2 3)Supp. 2055)Rat 4 1512 2 2 1971 ) 2 4) 1514) 3 1 3902 3 3 6990 3 2 5323 3 4 4367 4 2 5323 Total Av. 8519' 4 4 • 4367 Tot. Av. 8577 4 1 5362 Rat 1 10211 4 3 4099 Rat 3 10836 5 2 8370 Rat 2 7283 5 4 4036 Rat 4 5673 5 1 4752 5 3 9127 6 2 1167.7 Total Av. 6 4 8251 Total Av. 6 1 9035 353$ increase 6 3 7338 461$ increase 7 ,2 7048 7 4 5908 8 2 7048 8 4 5908 7 1 8460 7 3 12430 8 1 16309 8 3 .4781 9 2 6194 9 4 6871 9 1 9844 9 3 13107 10 1 16916 10 3 19827 11 1 16916 11 3 19827 18. Table TV also shows the average weight gains of male and female rats, both control and apple-fed. Figure 2 gives a graphic illustration of the average growth rates of the rats, as shown in the previous table. Table V shows the data obtained from the activity measure-ments made on rats fed Laboratory Chow, one group receiving a riboflavin supplement. It will be seen that two sets of figures were obtained from each rat at the start of the experiment. In the case of the riboflavin supplemented rat, no supplement was fed until these figures were ob-tained. These served to give an indication of the activity of the rats before any changes in the diet were made. They also show the increase in activity which occurs with any rats between the first few tests and succeeding tests after the animals have become accustomed to the activity cages. Also given in Table V are the average numbers of drum revolutions made by each rat within one test period. These are shown separately for each of the four segments of the table. Shown also are the average drum revolutions for both basic and riboflavin-supple-mented rats. Figure 3 illustrates graphically the average activity increases between the introductory runs (i.e. before rats accustomed to cages) and the later tests, and the much greater increase in the case of the riboflavin fed rats. In this chart the introductory test runs are expressed as 100 per cent activity, and the increases above these.levels are shown as correspondingly larger figures. FIGURE 3. Percent Increase in Physical Activity ^of Rate Fed Basic Ration and Riboflavin Supplemented Mation,Over Activity of Same Rats at Start of Test P e r i o d . 300# 200*2 111 20. It will be seen that the basic fed rats showed an activity-increase of 353 per cent, while those receiving a supplement of riboflavin showed an increase of 461 per cent. In the following pages will be found the data obtained from Experiment 17. Table TI gives the data obtained from the standard ribo-flavin solutions which were made to definite concentrations as shown and titrated with standardized HaOH. The "calibration curve" developed from these standards is shown in Figure 4-. Table VII contains the titration results of the cultures grown with supplements of apple extract of riboflavin. Shown also is the riboflavin content for each tube, obtained,by reference to the "calibration curve" • (Fig. 4), and the riboflavin content of the apple calculated from the data on each tube and expressed as milligrams of riboflavin per 100 grams of apple. Six tubes were used in each series of determinations and received.the equivalent of the following quantities of apple, as riboflavin extract:. Tube 1 1.5 mg. Tube 2 3.0 mg. Tube 3 6.0 mg. Tube 4 9.0 mg. Tube 5 12.0 mg. Tube 6 15.0 mg. RESULTS OF TITRATIONS OF STANDARDS No. of cc of .IN laOH Riboflavin Content/Tube .6 cc 1.5 2.25 2.25 5.20 6.55 7.90 9.20 0.15 1.50 2.15 3.35 5.45 6.70 9.05 13.50 0.6 1.60 0.90 0.95 3.60 1.85 9.95 12.85 0.0 ii gm. 0.05 6.075 0.10 0.15 0.20 0.30 0.50 0.0 0.05 0.075 Q.10 0.15 0.20 0.30 0.50 0.0 0.05 0.075 0.10 0.15 0.20 0.30 0.50 TABLE 71 (Cont'd) 22. RESULTS OP TITRATIONS OP STANDARDS No. of cc of .IN NaOH Riboflavin Content/Tube 1 3.4 cc 0.0 u gm. 2 3.7 • : • • 0.05 . 3, 2.5 0.075 4 4.5. 0.10 : 5 6.4 0.15 6 ' 6.45 0.20 7 8.50 0.30 8 11.10 0.50 1 0.20 . 0.0 .  2 1.30 0.05 3 1.45 . 0.075 4 2.15 0.10 5 4.35 0.15 6 6.20 ' 0.20 7 8.0 0.30 8 10.50 . 0.50 1 0.90 0.0 2 1.60 0.05 3 0.075 4 2.35 0.10 5 3.90 0.15 6 5.70 0.20 7 1.3 0.30" .8 0.0 0.50 TABLE 711 24. TITRATION OF RIBOFLAVIN EXTRACT OF JONATHAN APPLE cc of .IN NaOH Ribo. Content/Tube Mgm, Ribo. /lOO gms. (5) 1. 0.5 cc 0.0 u gm. 0.0 mgm. 2. 5.4 0.16 5.3 3. 6.0 0.18 3.0 4. 5.2 0.15. 1.2 5. -6.25 0.185 1.5 6. 0.6 - — 1. 1.3 0.04 2.7 2. 1.75 0.06 2.0 3. 1.45 0.045 0.75 4. 1.30 0.04 0.44 5. 1.85 0.065 0.54 6. 1.50 0.05 0.33 1. 0.65 .010 0.7 2. 0.70 .015 0.5 3. 0.85 .02 0.3 4. 1.10 .035 0.4 5. 5.20 .145 1.2 6. 1.10 .035 0.2 1. 1.1 .035 2.3 2. 1.5 .05 1.7 3. 2.1 .075 1.3 4. 1.8 .062 0.7 5. 2.5 .082 0.7 6. — 1. 1.1 .03 2.0 2. 1.5. .05 1.6 3. 2.1 .075 1.25 4. 1.8 .06 0.7 5. 2.5 .08 0.7 6. — • Average of a l l reasonable figures 1.8 n ag./lOO gm.= 18 Average of highest figures obtained 3.2 mg./lOO gm.=32 ppm. Low 8.5 ppm. 25. DISCUSSION OF RESULTS An inspection of Table II w i l l show that the apple supplement resulted i n an appreciable increase i n the physical activity of the female test rats. Table III seems to show a corresponding increase i n the metabolic rate, of the apple-fed female rats. There i s also some evidence that the reproductive capacity of the rats was i n - . creased by the apple supplement. Experiment II has shown that a supplement of apples can bring about an increased growth rate i n young rats, both male and female. Under favourable conditions, physical activity and rate of growth of young animals could be increased by the addition of almost any of the essential nutrient factors. This would only occur i f a definite deficiency of the supplemented factor existed. As may be observed i n Table I, the common nutrient factors are present i n the Laboratory Chow in quantities which should f a c i l i t a t e normal development and activity. The introduction of the apple supple-ment to this diet, moreover, had the effect of reducing slightly the total quantities of nutrients consumed by the rats, although not to a sufficient extent to affect the normal bodily functions. It i s apparent that the effects noted were not merely the addative result of an increased food intake. The poss i b i l i t y of the apple supplying some essential mineral nutrient and thus bringing about the benefits noted may be disregarded, as the Laboratory Chow contains a complete mineral mix which should eliminate any danger of a mineral deficiency occurring., 26. This evidence seems to indicate that the responses noted were brought about by some vitamin or other auxiliary nutritional factor. The fact that the male rats appeared to be very slightly, i f at a l l , affected by the apple supplement i s interesting. Table III shows a corresponding lack of stimulus to the rate of metabolism. I t may be characteristic of the nutritional factor involved that i t affects the male to a lesser degree than the female. This fact, coupled with the fact that the reproductivity of the apple-fed rats appeared to be -much greater than that of the controls possibly indicated an increase in the Vitamin E intake by the test rats. However, throughout the investigation i t has been noticed that male rats were characteristically less active than females, regardless of the diet. The possibility of Vitamin E being a factor contributing to the results obtained should not be overlooked, however, and further work along this line would be desirable. The growth stimulus shown to occur when an apple supplement i s fed to young growing rats, together with the effects already noted on the activity of mature animals seemed to point to riboflavin as a possible factor in bringing about these changes. Jfca^ &e»fflsa&i^ =^&9H§», ^he Purina Laboratory Chow contains 7.49 parts per million of ribo-flavin. The riboflavin requirement of rats for normal growth and activity i s 4.0 parts per million, but for reproduction 12.0 parts per million are required (4). This could possibly explain the stimulating effect which the apple supplement had on the reproductivity of mature females. 27. The riboflavin content of the Buckerfield*s dog meal was not determined, but as this product contains appreciable quantities of "Vita-grass" as well as other sources of this vitamin, i t is probable that a higher level exists than in the case of the "Laboratory Chow". Nevertheless, a supplement of apples has been shown to increase the growth rate of young rats fed this material. This effect could be possible i f , as according to Sherman (4) the effects of riboflavin tend to increase as the amount consumed i s increased. According to this theory the minimum bodily requirements are not the optimum, and increases i n the level above the minimum w i l l tend to increase the health and well being of the individual. He says, "Whether the plateau of optimal benefit i s reached at three or four times the minimal adequate intake, or whether there i s a further gain, measurable in the v i t a l i t y of the offspring and reflecting a further superiority of internal environment of the adults, up to levels of intake perhaps seven to ten times that of minimal adequacy is 3 t i l l a subject of active research." There are^certain factors which might possibly account for the difference in results between the earlier experiment in which an apple supplement was used (Experiment I ) , and the one involving a supple-ment of pure riboflavin (ExperimentHI) • These must not be ignored as there i s a distinct possibility that, had conditions been kept quite constant, much more consistent results would have been obtained. F i r s t l y , i t should be noted that the rats used for Experiment.1 were much older than those used for Experimentfll and had a much lower degree of physical activity (control female average, 178.5 revolutions per 24 hours) than did the others which had just reached 28. maturity (control average 8519 revolutions per 24 hours) and, therefore, may not have had sufficient time to develop the symptoms of a ribo-flavin deficiency. Secondly, the older rats of Experiment I had each borne two l i t t e r s of young before the tests were begun, but had been fed on the Laboratory Chow,containing a relatively low riboflavin level, throughout their lives. This could possibly bring about an appreciable depletion of riboflavin within the bodies of the female rats, and ray account for the fact that the females responded to an apple supplement whereas the males did not. Thirdly, the activity tests of Experimentfll were made using two activity cages. A l l basic rats were tested i n one cage, while a l l riboflavin-fed rats were tested in the other cage. This procedure, while convenient, may have led to an appreciable experi-mental error, as there could be a considerable difference in ease of operation between the two cages, resulting i n consistently higher, or lower, than normal readings for one group. Fourthly, pure riboflavin, being light sensitive, would tend to lose i t s potency quite rapidly while i n solution i n the water bottles of the rat cages. . Thus the actual amount of riboflavin which the test rats received was probably much less than the 20 parts per million originally made up in solution. Despite these possible errors, the work indicated that under the conditions described, a riboflavin supplement-can bring about increased activity, reflecting an improved physical condition. , 29. It has been indicated that the benefits resulting from the apple supplement used in earlier experiments were, i f not entirely, at least partially the result of an increased level of riboflavin. This, of course, can only be true i f i t can be shown that apples are capable of providing the riboflavin needed to bring about these changes. The data obtained from the riboflavin assay described previously shows a.great deal of variation. This i s unusual as the standards produced a smooth curve indicating satisfactory bacterial growth. While this work i s not purported to be an exact quantitative measure of the riboflavin present i n apple tissue, i t i s believed that the average figure obtained (18 ppm.) i s a f a i r indication of the abil i t y of apples to supply this vitamin. This figure i s far greater than that generally accepted as being present i n apples. The "Nutritional Charts" of the H. J. Heinz Co. (51 quote a riboflavin level of only .725 parts per million. I t must be remembered, however, that .most of the nutritional charts which are available are chiefly made up of information accumulated from various Other charts and references, some of which may be so old as to be no longer considered accurate. This is commonly done because of the tremendous amount of work which would be required to make a complete analysis of all.common foodstuffs. As very l i t t l e information i s available as to the nutritive value of apples, too much faith should not be placed in any one set of figures. , 30. According to Sherman (6) riboflavin can occur in several different chemical combinations i n food material as well as i n the free state, and consequently may not be shown in the results of some types of analysis. He says: "Whether riboflavin i n food is in the free s^ate, or i n combination with phosphoric acid, or with phosphoric acid and protein, probably makes l i t t l e difference to i t s nutritive value .... Hence statements of riboflavin values of foods do not distinguish as to whether, or i n what proportions, i t exists i n a free or a combined form.. It i s , however, to be kept i n mind that some of the methods by which i t has been sought to measure riboflavin i n vitro have failed to include that present i n combination (or in some of i t s combinations) so that uncritical compilations of data for riboflavin may include some values which are much below the true amounts." . I f this i s true i n the case of apples, and i n the light of •the information contained herein, such appears to be the case, then the statement that an apple supplement i n the diet of test rats can supply satisfactory quantities of riboflavin to f a c i l i t a t e normal physiological functions, appears to be essentially sound. 31. COICLUSIOITS From the evidence presented in the preceding sections of this paper the following points of information have been brought out. Fi r s t l y , i t has been definitely established that a supple-ment of apple in the diet of mature rats brings about.; great increases in physical activity of females. Also shown to be improved were the respiration rates, reproductivity, and growth rates of young rats. That these beneficial effects are the result of some auxiliary growth factor, probably a vitamin, there can be very l i t t l e doubt. Secondly, experimental evidence presented herein, together with the reports of other workers, suggests that a l l the beneficial effects previously noted could be brought about by an increase 'in the intake of riboflavin by the test animals, provided that a deficiency of this vitamin existed. Thirdly, a microbiological assay for riboflavin in apples has shown that a supplement of this f r u i t in the test diet could bring about an appreciable increase i n the riboflavin level of that diet. These three points give foundation to the statement that apples make a valuable contribution of riboflavin to the diet, which, presumably i s not the sole reason for the benefits resulting from their use, but i s nevertheless an important factor contributing toward the production of these desirable results. 0 32. SUMMARY The work described in this paper on the nutrient value of Britis h Columbia apples, i s a phase of a larger project of the B. C. Research Council entitled ."Factors Affecting the Food Value of B. C. Fruits and Vegetables." The primary objective of the project is to obtain definite information about British Columbia apples which can be used to advertise this product on the World markets. The f i r s t phase of the project involved activity cage measure-ments made ,with mature rats.fed a basic ration, supplemented i n the case of some, with fresh apple. The female rats of the apple-fed group showed a remarkable stimulation of physical activity. They also showed an increased res-piration rate and a greater degree of reproductivity. A group of young growing rats was fed the basic ration and another group received this ration plus an apple supplement. It was shown, by periodic weighings, that the apple-fed rats made more rapid growth than did the controls. The possibility of these results being brought about by an increased level of riboflavin was discussed, and an experiment set up to determine the effects of a pure riboflavin supplement on the activity of rats. The results of this experiment were very similar to those obtained with an apple supplement, although not so strikingly significant. Finally, i t was shown by means of a microbiological assay, that fresh apples contained sufficient riboflavin to effectively 33. neutralize a deficiency of that vitamin, if included in the diet in appreciable quantities. The conclusion drawn was that apples should be regarded as a desirable dietary constituent containing valuable quantities of ribo-flavin, and apparently other .important nutrient essentials. REFERENCES Ralston Purina Co., The Care and Feeding of Laboratory Animals, St. Louis, Mo., Woodstock, Ont. Snell, E. E., and F. M. Strong, A Microbiological Assay for  Riboflavin, Industrial and Engineering Chemistry, Vol. 11, No. 6, pp 346-350, July, 1939. Riboflavin (Vitamin Bg) Microbiological Method - Tentative, O f f i c i a l and Tentative Methods of Analysis of the Association of O f f i c i a l Agricultural Chemists, Sixth Edition, Washington, D.C., 1945, p 613. Sherman, H. C., "Chemistry of Food and Nutrition", 6th ed., Macmillan, New York, 1941, p 377. H. J. Heinz Co., Research Dept., Nutritional Charts. Sherman, H. C., "Chemistry of Food and Nutrition", p 373-374. 

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