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A study of oxidized flavor in raw milk in relation to certain milk constituentsBeck, Glenn Hanse January 2011 (has links)
Typescript, etc. / Digitized by Kansas State University Libraries
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Flavour components of whiskeyMacNamara, Kevin 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Aged distilled spirits such as whiskey are complex mixtures of flavour compounds in an
ethanol-water matrix. The flavour compounds involved can have widely different volatility
and relative amounts. Many of the organoleptic properties that make whiskey suitable for
commercial sale have their origin in reactions occurring during the ageing process in oak
wood barrels.
To investigate the complex changes that take place during spirit ageing a preparative
fractional vacuum distillation process was developed. Both high and low volatility
compounds could be individually isolated as fractions and free from both the ethanol matrix
and the fermentation fusel alcohols. This allowed a range of sensory and analytical
procedures to be conducted on these fractions, in particular to investigate changes occurring
during ageing.
Gas chromatographic (GC) analysis of the low volatility fraction is complicated by the fact
that both the compounds and their ethanol matrix have very similar chromatographic
behaviour when separated simultaneously on standard chromatographic phases. Compound
and matrix co-elution becomes a major problem and conditions for mass spectrometric (MS)
investigation are disadvantageous. A two-dimensional GC configuration using dissimilar
chromatographic phases was configured to overcome these limitations. Using this approach
27 compounds were separated and identified. Headspace injection was used to increase
detection sensitivity. Changes with ageing for seven compounds present at very low levels
were quantified. In addition changes in the most abundant compounds were quantified by
standard split injection, and changes in trace level sulfur compounds by headspace injection
with sulfur chemiluminescent detection (SCD). Increases of the concentrations of pleasant
fruity ethyl esters and acetates were established. Volatile sulfides with generally objectionable
aroma showed concomitant major decreases.
Appropriate techniques could also be applied to the low volatility compounds recovered from
the whiskey water fraction. High temperature GC-MS analysis of an extract of the water
fraction allowed the identification of 30 compounds. Three phenolic esters were identified in
whiskey for the first time. These compounds were synthesised and shown to be contributory
to desirable ageing flavour. Increases in concentrations of 16 oak derived compounds during
alO year ageing period were established. Several compounds increased significantly over
this time period. Ratios of aromatic phenolic aldehydes, and changes in these ratios during
ageing, were unique to the type of barrel used in these experiments. This suggests that the
final sensory properties of aged whiskey may be more dependent on wood parameters than
previously thought.
Preparative reverse phase High Pressure Liquid Chromatography (HPLC) with an ethanol
water gradient was used to further fractionate an extract of the low volatility compounds.
Subsequent analysis and sensory testing allowed a group separation of compounds with each
group contributing characteristic attributes to the total flavour. One group contained the three
new phenolic esters together with a number of other unidentified compounds. This group was
found to be important for desirable ageing flavour that seems to develop slowly with time.
Further studies in this area to understand the individual and synergistic contributions of the
many facets of ageing chemistry will have important commercial implications. / AFRIKAANSE OPSOMMING: Verouderde spiritus soos Whiskey is 'n komplekse mengsel van geurstowwe in 'n etanolwater
oplossing. Die vlugtigheid van die geurstowwe asook die konsentrasies waarin hul
aanwesig is, varieer aansienlik. Verskeie van die sintuiglike eienskappe wat kommersiële
waarde aan whiskey verleen, het huloorsprong in reaksies wat tydens die verouderingsproses
in eikehoutvate plaasvind.
Ten einde die ingewikkelde veranderinge wat tydens die veroudering van spiritus plaasvind,
te ondersoek, is 'n preparatiewe fraksionele vakuumdistillasieproses ontwikkel. Hoogs
vlugtige en minder vlugtige verbindings kon geskei word in afsonderlike fraksies wat vry was
van etanol en fuselalkohole. Dit het die sintuiglike en fisies-chemiese analises van die
fraksies moontlik gemaak, veralom die veranderings wat tydens veroudering plaasvind, te
ondersoek.
Gaschromatografiese (GC) analise van die fraksie met 'n lae vlugtigheid word gekompliseer
deur die feit dat hierdie komponente en die etanol waarin dit opgelos is soortgelyke
chromatografiese eienskappe toon wanneer hul gelyktydig op standaard gaschromatografie
fases geskei word. Die gelyktydige eluering van dié komponente en etanol waarin hul
opgelos is, skep 'n probleem wat nadelig vir massaspektrometriese (MS) analise is. Die
beperkings is oorkom deur die gebruik van tweedimensionele GC en stasionêre fases met
uiteenlopende eienskappe. Op dié wyse is 27 verbindings geskei en geïdentifiseer. Die
veranderinge in konsentrasies tydens veroudering is vir sewe verbindings gekwantifiseer.
Veranderinge in die konsentrasies van die verbindings teenwoordig in die hoogste
konsentrasies is gekwantifiseer deur split-inspuitings, terwyl veranderinge in die spoorkonsentrasies
van vlugtige swawelverbindings mbv dampfase-inspuitings en met swawel
chemolumisensie deteksie (SCD) bepaal is. Toenames in die konsentrasies van die
aangename vrugtige esters en asetate is bepaal. Vlugtige sulfiede met meesalonaanvaarbare
aromas toon gelyktydige groot afnames.
Geskikte tegnieke is ook gebruik vir die herwinning van minder vlugtige verbindings met die
waterfase van whiskey. Hoë temperatuur GC-MS analises van 'n ekstrak van die waterfase
het die identifikasie van 30 komponente moontlik gemaak. Drie fenoliese esters is vir die
eerste keer in whiskey gevind. Hierdie verbindings is gesintetiseer en hul bydrae tot die
gewenste verouderingsgeur is sintuiglik bevestig. Toenames in die konsentrasies van 16
eikehoutverwante verbindings gedurende 'n verouderingsperiode van 10 jaar is bepaal. 'n
Betekenisvolle toename het voorgekom in die konsentrasies van verskeie van hierdie whiskey
verbindings. Die verhoudings van aromatiese fenoliese aldehiede en die verandering in die
verhoudings tydens veroudering was kenmerkend van die tipe eikehoutvat wat gebruik is. Dié
bevinding dui daarop dat die fenole sintuiglike eienskappe van verouderde whiskey meer
afhanklik mag wees van eikehout parameters as wat voorheen algemeen aanvaarbaar is.
Preparatiewe omgekeerde fase hoëdrukvloeistofchromatografie met etanol/water as 'n
gradient elueermiddel is gebruik om 'n ekstrak van die minder vlugtige verbindings verder te
fraksioneer. Verdere GC-, MS- en sintuiglike analise het die skeiding van groepe van
verbindings waarvan elk kenmerkende bydraes tot die totale geur lewer, moontlik gemaak.
Een groep het drie nuut geïdentifiseerde fenoliese esters, tesame met 'n aantal ongeïdentifiseerde
verbindings, bevat. Daar is vasgestel dat hierdie groep 'n belangrike bydrae maak tot
die gewenste geur wat klaarblyklik stadig tydens veroudering ontwikkel. Verdere ondersoeke
in hierdie verband om die individuele en sinergistiese bydraes van verskeie fasette van die
chemie van veroudering te verstaan, kan belangrike kommersiële implikasies hê.
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Development of a lexicon for staling aromas in North American lager and analysis of consumer preference and differenceEdwards van Muijen, Christina Veronique 19 December 2001 (has links)
Staling in beer is inevitable. Oxidation and increased temperatures are the
main causes of stale flavors in bottled beers. Since 1934, research has been done
to identify compounds and pathways involved in creating stale flavors. Although
many research papers report stale flavors, there is not a lexicon per se of stale
aromas for North American lagers. This study has been divided into two parts, 1)
the process of developing a lexicon for stale aromas for North American lagers and
its application, and 2) the use of a consumer panel to determine whether the North
American lager consumer has a preference for aged versus fresh beer and whether
the consumer could perceive a difference between the two.
In the first study, three brands of North American lagers were aged in
27°C storage for three months and 38°C storage for two weeks. A lexicon for
staling aroma for North American lagers was created, using a trained descriptive
panel. The lexicon had two tiers; the first tier had five descriptors that were
category headings for the second tier of descriptors. Panelists were instructed to
rate the first tier descriptors, but using the descriptors in the second tier was
optional.
To validate the lexicon, descriptive analysis was performed on the stored
samples. The data were analyzed using principal components analysis (PCA) for
the first tier descriptors and generalized procrustes analysis (GPA) for the second
tier descriptors. The lexicon was used successfully, characterizing the control
beers as sulfury and fruity and the aged beers as sweet brown. Within the sulfury
category, panelists described control beers with the attributes perm solution and
skunky. Within the sweet brown category, panelists described the aged beers with
the descriptors baked pineapple and honey. The beers stored at different storage
temperatures behaved differently across time. The maps constructed with PCA
and GPA show a tendency for control samples to start out sulfury and, through
time, age with sweet brown characteristics.
In the second study, a consumer panel was implemented to 1) determine if
the average North American lager consumer had a preference for fresh versus
stored beer, and 2) to determine if perceivable differences existed between the
fresh versus stored samples.
A consumer test was designed using the three North American lagers that
were tested in the trained panel. The target number of consumers for each brand
was 100. The aged beer was stored at 38°C for 1 and 2 weeks, and the control was
stored at 1°C for that time period. A preference test, followed by a triangle test,
was performed on control versus 1 week at 38°C and control versus 2 week at
38°C for each brand (2 preference and 2 triangle tests for each brand; control
versus 1 week and control versus 2 weeks). The results showed no significant
preference for any brand/time point. Brand A had the only significant difference
(p <0.05) between samples stored at 38°C for 2 weeks and the control (The results
showed no preference). Additional research must be done for more conclusive
information, but this research shows that a small group of North American lager
consumers do not have a preference between aged beer and fresh beer and, for the
most part, cannot tell a difference between aged beer and fresh beer. / Graduation date: 2002
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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
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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
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Milk flavorsMantha, Venkat R January 2010 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
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Effect of oxygen on the development of off-flavors in UHT milkWadsworth, Katherine D. January 1984 (has links)
Call number: LD2668 .T4 1984 W33 / Master of Science
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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
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Electrophoretic studies of oxidized and normal flavors in milkBeetch, Ellsworth Benjamin. January 1951 (has links)
Call number: LD2668 .T4 1951 B45 / Master of Science
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Effectiveness of various vacuum, temperature, and steam treatments in reducing feed flavors in milkCotner, Edwin Carl. January 1958 (has links)
Call number: LD2668 .T4 1958 C67 / Master of Science
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