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Sensory evaluation and volatile compound analysis of strawberry fruit with and without modified atmosphere packaging (MAP) Shamaila, Mawele M.
Abstract
In the last few years, packaging of horticultural commodities in polymeric film pouches as means of extending their shelf life has expanded at the retail level. The modified atmospheres in commodity-containing pouches which consist of elevated levels of C02 and reduced levels of 02 may influence the quality attributes of the edible tissues. In this study, strawberries were stored at 1°C for 10 days under modified atmosphere package (MAP) conditions in high barrier film pouches flushed with either carbon dioxide (100% C02) , mixed gas (11% C02 + 11% 02 + N2 as balance) or air to assess relationships between sensory attributes, chemical parameters and gas chromatographic data by applying multivariate statistical techniques. The first two principal components which accounted for 92% of variance indicated that the changes in sensory quality of strawberries evaluated by quantitative descriptive analysis (QDA) were mainly a contrast of desirable (strawberry odor, texture and sweetness) against undesirable attributes (off-odor, fermented odor, musty odor and bitterness). Strawberries stored for only a few days were associated with desirable attributes. Deteriorated samples due to treatment and/or storage time as a result of changes in C02 and 02 were associated more with undesirable attributes. There were statistical differences in nearly all attributes studied between different treatments over storage time. Packaged strawberries treated with air retained their desirable attributes for longer storage time than those treated with mixed gas or carbon n dioxide, while unpackaged fruit developed fungal growth after 6 days of storage at 1°C. As the storage time increased, the ethanol concentration increased in strawberries packaged in the different gases, with mixed gas treated samples showing the highest amounts. Significant correlations were obtained between desirable and undesirable attributes, and with soluble solids and ethanol content. Most of the fifty volatile compounds extracted by a dynamic headspace purge-and-trap (DHPT) technique and adsorbed onto Tenax GC were identified by gas chromatography/mass spectrometry (GC/MS) as esters. Total relative amounts of volatile compounds and total amounts of butanoates from strawberries stored under different MAP conditions were much lower than for unpackaged strawberries. Significant correlations were found between odor attribute values and volatile compounds such as methyl butanoate, 1-methylethyl hexanoate, 3,7 dimethyl-1,6-octadien-3-ol and ethyl heptanoate. Multiple regression of 25 selected volatile compounds with the odor attribute values accounted for up to 70% of the variation, while stepwise regression selected between 6 and 9 variables with up to 67% of variance being explained. The data for 25 selected volatile compounds for untreated and gas-treated strawberries were subjected to canonical variate analysis (CVA). Samples held in air, mixed gas and the unpackaged fruit and strawberries evaluated at day 0 were all initially separated from strawberries held in carbon dioxide. After 10 days in storage, all MAP strawberries were classified in close iii proximity, with the indication that quality attribute scores were low. This was attributed to elevated C02 and reduced 02 levels in packages containing the strawberries. Assessment of volatile compound data by CVA could be valuable in monitoring quality of strawberries and supplementing sensory evaluation of the fruit stored under various conditions. In a separate experiment, 6 strawberry cultivars, 'Mrak', 'Ranier', 'Redcrest', 'Selva', 'Sumas' and 'Totem' were compared for sensory and chemical properties, and selected volatile compounds. 'Redcrest' had the most intense sourness, lowest pH, high titratable acidity and lowest overall fruit quality. Twodimensional partitioning (TDP) showed that the overall quality of the strawberries was primarily dependent on odor and sweetness level. Cultivars differed in all orthogonal variates except odor. While judges could not detect odor differences, the total relative amounts of volatile compounds were greatest for 'Mrak' and 'Selva'. Canonical variate analysis (CVA) based on volatile compounds classified the cultivars according to the region in which they were bred.
Item Metadata
Title |
Sensory evaluation and volatile compound analysis of strawberry fruit with and without modified atmosphere packaging (MAP)
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
1992
|
Description |
In the last few years, packaging of horticultural commodities in
polymeric film pouches as means of extending their shelf life has
expanded at the retail level. The modified atmospheres in
commodity-containing pouches which consist of elevated levels of
C02 and reduced levels of 02 may influence the quality attributes
of the edible tissues. In this study, strawberries were stored at
1°C for 10 days under modified atmosphere package (MAP) conditions
in high barrier film pouches flushed with either carbon dioxide
(100% C02) , mixed gas (11% C02 + 11% 02 + N2 as balance) or air to
assess relationships between sensory attributes, chemical
parameters and gas chromatographic data by applying multivariate
statistical techniques.
The first two principal components which accounted for 92% of
variance indicated that the changes in sensory quality of
strawberries evaluated by quantitative descriptive analysis (QDA)
were mainly a contrast of desirable (strawberry odor, texture and
sweetness) against undesirable attributes (off-odor, fermented
odor, musty odor and bitterness). Strawberries stored for only a
few days were associated with desirable attributes. Deteriorated
samples due to treatment and/or storage time as a result of changes
in C02 and 02 were associated more with undesirable attributes.
There were statistical differences in nearly all attributes studied
between different treatments over storage time. Packaged
strawberries treated with air retained their desirable attributes
for longer storage time than those treated with mixed gas or carbon
n
dioxide, while unpackaged fruit developed fungal growth after 6
days of storage at 1°C.
As the storage time increased, the ethanol concentration
increased in strawberries packaged in the different gases, with
mixed gas treated samples showing the highest amounts. Significant
correlations were obtained between desirable and undesirable
attributes, and with soluble solids and ethanol content.
Most of the fifty volatile compounds extracted by a dynamic
headspace purge-and-trap (DHPT) technique and adsorbed onto Tenax
GC were identified by gas chromatography/mass spectrometry (GC/MS)
as esters. Total relative amounts of volatile compounds and total
amounts of butanoates from strawberries stored under different MAP
conditions were much lower than for unpackaged strawberries.
Significant correlations were found between odor attribute values
and volatile compounds such as methyl butanoate, 1-methylethyl
hexanoate, 3,7 dimethyl-1,6-octadien-3-ol and ethyl heptanoate.
Multiple regression of 25 selected volatile compounds with the odor
attribute values accounted for up to 70% of the variation, while
stepwise regression selected between 6 and 9 variables with up to
67% of variance being explained.
The data for 25 selected volatile compounds for untreated and
gas-treated strawberries were subjected to canonical variate
analysis (CVA). Samples held in air, mixed gas and the unpackaged
fruit and strawberries evaluated at day 0 were all initially
separated from strawberries held in carbon dioxide. After 10 days
in storage, all MAP strawberries were classified in close
iii
proximity, with the indication that quality attribute scores were
low. This was attributed to elevated C02 and reduced 02 levels in
packages containing the strawberries. Assessment of volatile
compound data by CVA could be valuable in monitoring quality of
strawberries and supplementing sensory evaluation of the fruit
stored under various conditions.
In a separate experiment, 6 strawberry cultivars, 'Mrak',
'Ranier', 'Redcrest', 'Selva', 'Sumas' and 'Totem' were compared
for sensory and chemical properties, and selected volatile
compounds. 'Redcrest' had the most intense sourness, lowest pH,
high titratable acidity and lowest overall fruit quality. Twodimensional
partitioning (TDP) showed that the overall quality of
the strawberries was primarily dependent on odor and sweetness
level. Cultivars differed in all orthogonal variates except odor.
While judges could not detect odor differences, the total relative
amounts of volatile compounds were greatest for 'Mrak' and 'Selva'.
Canonical variate analysis (CVA) based on volatile compounds
classified the cultivars according to the region in which they were
bred.
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Extent |
7565637 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-01-09
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0098939
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1992-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.