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Flavor characterization of selected acidulants in model and food systemsHartwig, Pam A. 02 September 1994 (has links)
Acidulants can contribute considerably to the flavor of food.
However, limited research on differences in acid flavor exists. While
numerous researchers have studied acids, most have focused on sourness
exclusively. Acids have been shown previously to differ in non-sour
components, such as bitterness and astringency. A series of experiments
were conducted to determine flavor characteristics of selected acids in
different systems.
First, selected acids (lactic, malic, citric, acetic) and 2 acid blends
(lactic/acetic 1:1 and 2:1) in a model (water) system were evaluated on an
equivalent weight (0.2% w/v) and on an equivalent pH basis. Three pH levels were explored: 3.5, 4.5 and 6.5. The technique of free-choice profiling was applied to characterize the flavor profile. Results analyzed by
generalized procrustes analysis showed two significant findings: (1) acids
differ in sensory character, and (2) the flavor of an acid changes with pH.
Second, selected acids (lactic, malic, citric, tartaric) were evaluated in
sweetened, flavored drinks on an equivalent weight basis at two
concentrations (0.4 and 0.6% w/v). Four flavors were evaluated: orange,
cherry, cola and strawberry. Descriptive analysis was used, and the data was
analyzed by principal component analysis. Significant differences were
found on among acids and concentrations. For the orange flavor system,
citric acid enhanced the orange flavor of the drink.
Third, selected acids (lactic, citric, acetic) and 2 acid blends
(acetic/lactic 1:1 and 2:1) were evaluated in emulsions on an equivalent pH
basis. Three pH levels were explored: 3.5, 4.5 and 5.5. These findings
support the first study as differences were found among acids, and flavor
changes existed when pH changed. / Graduation date: 1995 Read more
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Sensory and chemical analysis of 1997 Oregon Pinot noir enzyme treated winesGoldberg, Naomi 04 December 1998 (has links)
Pinot noir has a reputation for lower color stability than other red wine varieties.
Because it has relatively low anthocyanin and phenolic content and lacks acylated
anthocyanin pigments compared to other red vinifera varieties, color extraction and
stability are particularly important. Varying the processing during fermentation of red
wine can produce high quality wines. Pectolytic enzymes are used in wine processing for
many purposes from increasing juice yield and filtering rates to improving color and
phenolic extraction.
Macerating enzymes used in this study, Scottzyme Color Pro (Scott
Laboratories), Scottzyme Color X (Scott Laboratories), Lallzyme EX (Lallemand), GB
Rapidase EX Color (Gist Brocades), and Vinozyme G (Cellulo) were added to 1997
Oregon Pinot noir must prior to fermentation to observe color, aroma and flavor changes.
These commercial enzymes have been reported to increase color and improve aroma and
flavor of red wines. The effect of these enzymes had not previously been investigated on
Oregon Pinot noir but the manufacturers reported increased polymeric phenols, polymeric
anthocyanins, tannins, color stability, red hue and saturation of red wine varieties. These
enzymes have varying manufacturer recommended usage levels and it is not known how the dosage levels and the enzymes themselves affect Oregon Pinot noir. Sensory
evaluations of these wines, at a high and low dosage level, were conducted through free-choice
profiling by winemakers and descriptive analysis from a trained panel. In addition,
chemical analyses were performed and related to sensory panel results.
Overall the addition of these enzymes to Oregon Pinot noir produced wines with greater
purple, red descriptors and higher color intensity than the control wine from trained
descriptive panel and winemaker panel results. In aroma, the enzyme treated wines were
higher in vegetative and earthy descriptors compared to the control. GB Rapidase EX
Color (Gist Brocades) was higher in bitterness flavor compared with other samples.
Low enzyme wine treatments separated wine samples more from the control then high
enzyme wine treatments. The color and appearance, aroma and flavor axes of the profile
maps were not significant in the high enzyme treated wines as determined from the
winemaker panel. Furthermore, the winemaker panel found acidity the only aroma or
flavor descriptor significant in the high dosage ANOVA results. Whereas six descriptors
in the low enzyme ANOVA results were significant in separating aroma and flavor
samples. Except for Lallzyme EX (Lallemand) treated wine, the hunter colorimeter results
showed all low enzyme treated wines were significantly (p<0.05) more red-purple (lower
hues) than the high enzyme treated wines. / Graduation date: 1999 Read more
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A maturity trial study of Pinot noir wines : aroma profile by sniffing gas chromatographic effluentMiranda-Lopez, Rita 07 December 1990 (has links)
The quality of wine is highly influenced by the weather.
Temperature, solar radiation and humidity influence the
formation and concentration of aroma-active compounds and
aroma-active precursors in the grapes. Pinot noir grapes require
a slow ripening, under cool temperatures, in order to achieve
their fullest flavor. The main objective of this study was to
provide an overall aroma picture that could help, along with the
chemical indices, to decide the optimum harvesting time to
obtain certain distinctive aroma attributes in the wine.
This particular work represents the first stage in a broad
plan aimed to understand the dependence of the wine flavor
chemistry on the ripening of the grapes. This maturity trial
was planned to last several years; it was expected that the
outcome and techniques developed in the present study would be
essential in delineating the steps to follow. The results of the
aroma analyses for the 1987 and 1988 vintages are reported
here. In each vintage, Pinot noir grapes were harvested at three
different times, covering a range from early to late maturity.
A sniffing technique based on gas chromatographic aroma
detection by a trained panel was implemented. This technique
has proved to be a useful tool to measure qualities and
intensities of aromas. The method was effective in detecting
many of the aroma-active compounds and in identifying aroma
differences between the wines studied.
The aroma profiles for the wines were found to be very
different from each other within and across vintages. There
were only 10 aroma peaks common to all three 1987 wines, 16
aroma peaks common to the 1988 wines, and 4 aroma peaks
common to both vintages. Late maturity wines had more aroma-active
peaks than the other 2 wines for both vintages. The 1988
wines had a higher number of aroma-active peaks than the 1987
wines. The percentages of aroma-active peaks not detected by
the Flame lonization Detector (FID) were 45% in the 1987
wines, and 66% in the 1988 wines. The overall climatic
conditions in those years were very different. The 1987 season
was characterized as hot and dry, producing an early harvest.
The weather in 1988 was more of a typical season for Oregon,
producing a normal to late harvest. Further study is needed to
fully understand the flavor chemistry occurring during grape
ripening. / Graduation date: 1991 Read more
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Sensory changes in high pressure processed vs. heat processed food systems over timeRodakowski, Andrea M. 23 February 1999 (has links)
This study was undertaken to determine the sensory differences in high pressure vs. heat
processed food systems after storage at ambient and refrigerated temperatures as
determined by a trained sensory panel. Spanish rice and spaghetti with meat sauce were
prepared and treated with heat and with high pressure processing (HHP). A citrus fruit
mix consisting of pieces of orange, grapefruit, and pineapple was processed by mild heat
and HHP, and heat alone.
One day after processing, treated products were tested along with untreated
controls. Products were stored at either 22°C or 3°C, and tested at 10, 30, 60, 90, and
120 days. Sensory testing was done by a panel trained in a QDA-type method, and data
was analyzed by univariate and multivariate methods.
For spaghetti with meat sauce, significant differences (p>0.05) were found between
processing methods stored at the same temperature in appearance and texture attributes,
with the high pressure processed samples closer to unstored product than those treated by
heat. Differences in treatments first appeared in 'dry appearance' at 10 days, and by 120
days there were differences in 'tomato integrity', 'pasta integrity', 'brightness of color', and 'firmness of pasta' as well. Most of these differences were due to the stickiness
caused by the extra amylose leaking out of the heat treated pasta over time.
For Spanish rice, there were no statistically significant differences between
samples processed by the two methods and stored at the same temperature. The Spanish
rice was formulated with parboiled rice, which allows very little amylose leakage, so it
did not show amylose-related effects as the spaghetti with meat sauce did.
The fruit mix processed with HPP and mild heat had significantly higher ratings
in appearance attributes 'brightness of color' and piece integrity', and lower ratings in
'cooked' descriptors than product treated with heat alone stored at the same temperature. / Graduation date: 2000 Read more
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Interrelationships among changes in flavor and aroma, and composition of stored strawberry juice concentrateLundahl, David S. 27 January 1989 (has links)
Sensory evaluation and instrumental methods were applied to the
evaluation of strawberry juice concentrate (68°Brix) stored at
20°C which had been produced both commercially (C-SJC) and in a
pilot plant (SJC). Sensory evaluation included taste and aroma
ratings by intensity scaling and time-intensity of taste, and visual
colorimetry by matching Munsell color chips. Instrumental analyses
included tristimulus colorimetry (i.e. Hunter colorimeter),
spectrophotometric colorimetry for pigment analyses, titrametric
analyses for acidity (pH and titratable acidity) and free α-amino
acids (formol number), and headspace gas analyses for CO₂ and O₂.
During six days storage of C-SJC, a decrease in concentration of
anthocyanins and increase in polyphenolics (tannin) was associated
with an increase in astringency. Free α-amino acids were
observed to decrease, while CO₂ was released. These changes were
associated with an increase in musty/moldy and pungent aromas. Free
sugars and titratable acidity did not change.
The pilot plant SJC was processed from blanched and unblanched
fruit to evaluate the relative importance of oxidase activity (i.e.
polyphenoloxidase) prior to pasteurization. The blanching treatment
increased the astringency and sourness in unstored SJC. These
affects were associated with an increase in concentration of
polyphenolics (tannin). During storage, the blanch treatment
decreased the rate of anthocyanin loss and decreased the release rate
of CO₂, yet degradation rates were still high. The 0₂
concentration in headspace did not change significantly during
storage indicating that polyphenoloxidase (PPO) activity during
storage was low. The musty/moldy and pungent aromas increased
similarly to C-SJC.
A chemical mechanism accounting for these changes is proposed
where products from the oxidative degradation of ascorbic acid
contribute directly or indirectly to the degradation of anthocyanins
to yield browning. Further, high initial concentrations and
subsequent decreases during C-SJC storage of free α-amino acids
indicate that Strecker degradation is a participating mechanism.
Associations of browning with the development of off-flavors suggest
this chemical mechanism forms odor-active volatile compounds. / Graduation date: 1989 Read more
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Sub-threshold effects on the perceived intensity of recognizable odorants : the roles of functional groups and carbon chain lengthsLopetcharat, Kannapon 06 September 2002 (has links)
Sub-threshold effects were studied in binary and tertiary mixtures
comprising a panel-recognition-concentration odorant and sub-threshold odorant(s).
Sub-threshold condition was maintained by controlling the sub-threshold
concentration as percentages of subjects' individual detection threshold. The
perceived intensities (overall intensity and several descriptors) of recognizable
odorants were rated using magnitude estimation.
Sub-threshold suppression was common and concentration independent in
mixtures comprising odorants with different functional groups. Suppression was
observed at the lowest sub-threshold concentration tested (30% level). At sub-threshold
concentrations, acetic acid suppressed the perceived intensity of acetaldehyde and ethanol but not vice versa. Acetaldehyde and ethanol, however,
suppressed each other when one was at sub-threshold concentrations in binary
mixtures. Enhancement was observed in tertiary mixtures containing acetaldehyde
at panel recognition concentration and was dependent on sub-threshold
concentrations of acetic acid and ethanol.
In mixtures that contained aliphatic acids with different carbon chain
lengths (acetic acid, propanoic acid and n-butanoic acid), sub-threshold
enhancement and suppression depended on concentrations and molecular similarity
of mixture components. Sub-threshold effects were not observed when the acids
were two carbon-atoms different. 50% and 70% sub-threshold levels caused sub-threshold
enhancement; however, higher concentrations caused decrease in
intensity. Sub-threshold suppression was observed in mixtures containing n-butanoic
acid as a recognizable odorants with propanoic acid at a 10% level in a
binary mixture and acetic acid and propanoic acid in a 30%-30% combination in
the tertiary mixture. / Graduation date: 2003 Read more
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Development of methods for analysis and sensory threshold determination of malt derived flavor components in beerLukes, Bryce K. 17 May 1988 (has links)
Malt, wort and beer samples representing a single
pilot brew were extracted from Celite columns with Freon
114. Total extracts were analyzed by gas
chromatography/mass spectrometry. Compounds were
identified that were unique or common to beer, wort or
malt and quantities present were determined for those
common to the three sample types.
Concentrated extracts were separated by liquid
chromatography on partially deactivated silica gel packed
in Teflon tubes, using Freon 11 as the solvent.
Fractions from liquid chromatography were analyzed by
descriptive sensory evaluation. Those fractions selected
as bearing cereal-like, grassy, nutty or malty aroma
characteristics were analyzed by gas chromatography.
Freon extracts and fractions were found suitable for
descriptive sensory evaluation and this was used to advantage in locating fractions with the desired aroma
characteristics. Cereal-like, grassy, nutty or malty
aroma characters were associated with liquid
chromatographic fractions containing primarily alcohols,
aldehydes and ketones.
The Ascending Method of Limits for determination of
the threshold of added substances in beer was critically
reviewed and a new threshold test was developed. The new
test design reduces the sample requirement from eighteen
to twelve for each session. In contrast to the Ascending
Method of Limits, the new test design was amenable to
statistical evaluation and statement of a level of
confidence for the threshold intervals determined.
Both a nine-point intensity scale of difference from
the labeled reference and a category scale were applied
to the new test design. Intensity scale data were
normalized and subjected to analysis of variance and a
series of one-sided t-tests to determine individual and
combined panel threshold intervals. Category scale data
were analyzed by a rank sums test to determine individual
thresholds and the R-index values thus obtained were
subjected to analysis of variance and orthogonal
contrasts of means to establish the combined panel
threshold.
The intensity scale method applied to the new test
design provided the lowest and narrowest estimates of the
threshold interval in comparative testing with the category scale method and the Ascending Method of Limits
and, in addition, required fewer replications than the
category scale method to establish the threshold
interval. / Graduation date: 1989 Read more
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Influence of sugar and acid on sensory qualities and desirability of blackberry juice drink using response surface methodologyPerng, Chiou-mey 08 July 1988 (has links)
Response Surface Methodology (RSM) was used to study the effect
of two variables, sugar level (12-16 °Brix) and acid level (0.3-0.7
% T.A.) on sensory qualities and desirability of blackberry juice
drinks. Three blackberry juice levels (10%, 15%, and 20%) were used
to study the influence of juice flavor on sensory qualities and
desirability of the juice drinks. A trained panel evaluated three
attributes, blackberry flavor, sweetness, and sourness intensities,
of the juice drinks. The consumer panel gave desirability and three
attributes just-right ratings. A Balanced Complete Block Design was
used.
Blackberry flavor intensity was enhanced by sugar level.
Blackberry flavor intensity was enhanced by acid level to a point
about 0.5% T.A., and then decreased. Blackberry flavor intensity was not related to °Brix:acid ratio and was only related to the
sweetness:sourness ratio at the 20% juice level. Sweetness and
sourness intensities increased with increasing sugar and acid
levels. There was a suppression effect of sugar and acid on each
other in the juice drink. The relationships of sweetness, sourness,
and sweetness:sourness ratios to °Brix:acid ratios were all
linear. Desirability rating was related to °Brix:acid and
sweetness:sourness ratios for the 10% and 20% juice levels, for 15%
juice level no association was found. The formula which received the
closest to "just right" ratings and highest overall desirability
rating had in a °Brix of 15.4 and a % titratable acidity of 0.64,
resulting in a °Brix:acid ratio of 24 and a corresponding
sweetness:sourness ratio of slightly less than 1.0. In general, the
15% juice level was the best because of its sugar and acid tolerance
and high desirability. / Graduation date: 1989 Read more
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Quality assessment of Asian noodles made from U.S. wheat flours using sensory descriptive analysisJanto, Mimi 11 December 1997 (has links)
As a major wheat exporter to countries all over the world, the United States has to
produce wheat that satisfy different quality requirements requested by their customers.
Over the past decade the United States has encountered a major problem, that of losing
market share in Asia to Canada and Australia. The major reason was that the United
States was unable to supply Asian countries with quality wheat suitable for noodle
production. To overcome the problem, the U.S. wheat industry needs to understand the
specific quality requirements required for Asian noodles. Research on understanding
sensory characteristics of Asian noodles was proposed to bridge the communication
barrier regarding Asian noodle quality. Descriptive analysis was utilized for this study to
provide sensory characteristics of noodles from different Asian countries.
In the first study, four classes of U.S. wheat flour samples were evaluated for their
ability to make high quality Taiwanese noodles. Taiwanese noodle industry
representatives came to the United States and made 4 major types of their noodles using
U.S. wheat flours; they evaluated them by employing both the Taiwanese industries' scoring system and modified descriptive analysis. The results of this study indicated that
hard white wheat was suitable for making two types of Taiwanese noodles (dry and yee
noodles), a blend of hard red winter and hard red spring wheat was suitable for wet
noodles, and a blend of hard red winter and white wheat was suitable for fresh noodles.
The second study was undertaken to better understand the texture profile of
noodles from various Asian countries. Sensory texture characteristics of fresh noodles
from Taiwan, Thailand, and Malaysia were identified. A total of 16 patent flour samples
for Taiwan, and 18 straight grade flour samples each for Thailand and Malaysia, were
milled from hard white wheat varieties and made into each Asian country's noodles. A
texture profile of each country's noodles was developed by an Oregon State University
descriptive panel while quality evaluation was performed by each countries' noodle
experts. The results characterized the Taiwanese noodles as the smoothest, springiest, and
highest in integrity of noodles; the Thai noodles were the hardest, most dense, cohesive
noodles and also higher in starch between teeth and toothpull; and the Malaysian noodles
were the softest, least dense, cohesive, and sticky noodles. The optimum protein to
achieve specific texture quality for each country was identified. / Graduation date: 1998 Read more
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Instrumental and sensory texture profile analysis of Asian wheat noodlesPipatsattayanuwong, Siriporn 06 May 1998 (has links)
Texture, a critical property of Asian wheat noodles, is normally assessed by
sensory evaluation. However, sensory evaluation may be impractical for wheat breeders
and noodle researchers who need to evaluate a large number of samples and have limited
sample. Instrumental Texture Profile Analysis (TPA) has been widely employed to
evaluate Asian wheat noodle texture. Nevertheless, a standardized method for
performing TPA on these products has not been established. A series of studies were
conducted to develop a testing method to best relate TPA results to sensory texture
characteristics of Asian wheat noodles.
First, the optimum TPA testing conditions (crosshead speed and degree of
deformation) were determined for each noodle category (alkaline, instant fried, salted
flat, and salted round), and were defined as the conditions which best related their results
to the sensory data. Partial Least Squares (PLS2) was used to examine relationships
between sensory first-chew characteristics (hardness, cohesiveness, springiness,
denseness, starch between teeth, and toothpull) and TPA output (peak areas and heights).
Response Surface Methodology determined the optimum TPA conditions (crosshead speed and % deformation) as follow: 1 mm/s and 85 % for alkaline, 1 mm/s and 70% for
instant fried and salted round, and 5 mm/s and 65 % for salted flat noodles.
Second, the effects of two sample cooking factors: noodle weights (20, 50, 100
g) and noodle to water ratios (1:10, 1:20) and three holding factors: media (with, without
water), temperatures (25, 55 °C), and times (2, 15, 30 min), on the TPA results were
investigated. Cooking factors did not significantly affect the TPA results but higher
holding temperatures, the use of water as a holding media, and longer holding time
significantly decreased most TPA parameters' values.
Third, relationships between TPA and sensory first-chew parameters were
examined for each noodle category. Predictive models of each sensory first-chew
attribute were developed using linear and nonlinear (Fechner and Stevens) models, with
single and multiple parameters. Hardness could be satisfactorily predicted by a single
TPA parameter (area 1 or area 2), but other attributes required multiple parameters in the
models to be satisfactorily predicted. Different model types were selected for each
sensory attribute and noodle category. TPA peak area 1 and 2 were the best predictors
for first-chew characteristics of cooked Asian wheat noodles. / Graduation date: 1998 Read more
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