Heat treated orange juice, both pasteurized and concentrate, are being increasingly consumed in the U.S. Orange juice is primarily heat treated to increase its shelf life, by curbing the growth of microorganisms; and to inactivate pectin methylesterase, which demethylates pectin and leads to cloud loss in the juice. However, because of heat processing, orange juice undergoes undesirable flavor changes that decrease its acceptability to consumers. The objectives of this study were to differentiate between fresh frozen and heat treated orange juice employing descriptive analysis, and to determine by Osme, a gas chromatography-olfactometry (GCO) method, odor active volatiles that were either lacking or created in the heat treated juice. The second objective was to determine how changes in the odor-active volatile profile of heat treated orange juice, relates to changes in the aroma and flavor intensities of the samples as assessed by descriptive analysis. Through descriptive analysis, the panel was successful in significantly (p<0.05) separating the fresh, pasteurized, and concentrate samples. Orange, orange peel, sweet, and grassy descriptors were found to be important for fresh aroma and flavor, while cooked, yam, metallic, tamarind, green bean and artificial orange descriptors were higher in heat treated samples. Using Osme, it was possible to separate fresh frozen from heat treated orange juice, on the basis of their aroma profiles. Fresh frozen samples show a higher concentration of peaks tentatively identified as gamma-butyrolactone, citral, nonanal, carvone, perillaldehyde, carvyl propinate, valencene, and other unidentified peaks possessing descriptors such as floral, lime, citrus, pine, bamboo leaf, metallic, and vinyl. Pasteurized samples show a larger concentration of peaks tentatively identified as hexanol, octanol, nerol / carveol, myrcene, 2-octanone, p-cymene, terpenen-4-ol, betacitronellol, and other unidentified peaks with descriptors such as cilantro, vinyl, melon, mushroom, and metallic. Descriptors such as orange, orange peel, sweet, grapefruit, and grassy are more pronounced in the fresh samples and are similar to the odor descriptors of Osme peaks higher in the fresh samples. Descriptors such as cooked, artificial orange, yam, metallic, tamarind, and green bean are higher in the pasteurized samples, and are similar to the odor descriptors of peaks higher in these samples. / Graduation date: 1999

During the course of ripening, Cheddar cheese frequently develops a flavor defect described as fruity. Recent work has indicated that the use of certain starter cultures ultimately results in the development of the defect as the cheese ages. The flavor compounds responsible for the defect, however, have not been elaborated. The purpose of this investigation was to isolate and identify the components responsible for the fruity flavor defect and to evaluate the role of certain cheese starter cultures in the development of the defect. Since the fruity character of the defect is apparent in the aroma of the cheese, the compounds responsible for the defect were expected to be reasonably volatile. Volatile constituents were isolated by a distillation technique from fat expressed from a typically fruity cheese by centrifugation. The volatile constituents were then separated by gas-liquid chromatography. By monitoring the odor of the effluent stream of the column, it was possible to determine which components had fruity odors, and these were subsequently identified by mass spectral analysis and coincidence of retention time with the authentic compounds. Ethyl butyrate, ethyl hexanoate, and ethyl octanoate were found to be the only compounds with detectable fruity odors. The volatiles from the fat of four cheeses possessing varying degrees of the defect and their matching non-fruity controls were analyzed by a gas entrainment, on-column trapping, gas-liquid chromatographic technique. The manufacturing and curing conditions of each fruity cheese and its matching control were identical, except for the use of different starter cultures. Ethanol, ethyl butyrate, and ethyl hexanoate were more abundant in each of the fruity samples. The approximate concentration range of these compounds was as follows: In fruity cheese; ethanol 400 to 2,040 ppm, ethyl butyrate 1.6 to 24 ppm, ethyl hexanoate 0.9 to 25 ppm. In non-fruity cheese; ethanol 36 to 320 ppm, ethyl butyrate 0.7 to 4.7 ppm, ethyl hexanoate 0.3 to 2.2 ppm. In ten commercial Cheddar cheeses selected at random from the market, the concentration of ethanol ranged from 5.5 to 620 ppm. Single-strain cultures of Streptococcus lactis, Streptococcus diacetilactis, and Streptocococcus cremoris as well as three mixedstrain commercial cultures were evaluated for ethanol and acetaldehyde production in non-fat milk medium. Among the single-strain cultures there appeared to be no correlation between ethanol production and species, although considerable variation was noted for strains within a species. The mixed-strain cultures were designated A, B, and C. Cultures B and C had been implicated in the development of the fruity flavor defect in Cheddar cheese, while culture A produced normal cheese of good quality. Cultures B and C produced approximately 40 times more ethanol than culture A when incubated in non-fat milk medium for one month at 7°C. Certain single-strain cultures and the three mixed-strain cultures were tested for their ability to reduce acetaldehyde and propanal, and to catalyze the formation of ethyl butyrate when ethanol and butyric acid were provided as substrates. Acetaldehyde and propanal were reduced to the corresponding alcohols by all cultures, but the formation of ethyl butyrate was not observed in any culture. A good correlation between high levels of ethanol and high levels of ethyl butyrate and ethyl hexanoate in the fruity cheeses suggests that the quantity of ethanol present in the cheese may determine the amount of ester formed. Further, starters resulting in the defect produced considerably more ethanol than cultures resulting in normal cheese when incubated at 7°C, a normal temperature for curing Cheddar cheese. This observation adds weight to the hypothesis that certain cultures are directly responsible for the defect. / Graduation date: 1966

A precision measurement of the CKM angle γ from tree-level processes is one of the principal goals of the LHCb experiment. The results from this study are compared to predictions from two different theoretical models and from the default LHCb tuning of the PYTHIA Monte Carlo event generator, and the results shown to be in good agreement. The cross-section results are also compared to an independent LHCb measurement. LHCb analyses rely on the ability to identify kaons and pions with a high efficiency and low mis-identification rate, achieved by two Ring Imaging Cherenkov (RICH) detectors. To ensure optimal performance of the RICH detectors, the time alignment of the Level-0 (L0) front-end electronics modules has been optimised using a combination of a pulsed laser system installed in the LHCb cavern and pp collision data. After the time-alignment procedure, the L0 modules have been time-aligned to within approximately ° 1ns across both detectors.

ATLAS measurements of the production of muons from heavy flavor decays in √sNN = 2.76 TeV Pb+Pb collisions and √s = 2.76 TeV pp collisions at the LHC are presented. Integrated luminosities of 0.14 nb−1 and 570 nb−1 are used for the Pb+Pb and pp measurements, respectively. The measurements are performed over the transverse momentum range 4 < pT < 14 GeV and for five Pb+Pb centrality intervals. Backgrounds arising from in-flight pion and kaon decays, hadronic showers, and mis-reconstructed muons are statistically re- moved using a template fitting procedure. The heavy flavor muon differential cross-sections and per-event yields are measured in pp and Pb+Pb collisions, respectively. The nuclear modification factor, RAA, obtained from these is observed to be independent of pT, within uncertainties, and to be less than unity, which indicates suppressed production of heavy flavor muons in Pb+Pb collisions. For the 0–10% most central Pb+Pb events, the measured RAA is ∼ 0.35. The azimuthal modulation of the heavy flavor muon yields is also measured and the associated Fourier coefficients vn for n=2, 3 and 4 are given as a function of pT and centrality. They vary slowly with pT and show a systematic variation with centrality that is characteristic of other anisotropy measurements. The measured RAA and vn values are also compared with theoretical calculations. We also present the ATLAS di-muon azimuthal correlation from heavy flavor decay in √√sNN = 5.02 TeV Pb+Pb collisions and s = 5.02 TeV pp collisions. Heavy flavor muons with 4 < pT < 8 GeV are selected. The azimuthal correlations are measured for both same sign muon pairs and opposite sign muon pairs. Comparing with the azimuthal correlations in pp data, Pb+Pb results are observed to have more broadening. Central collisions are also more broadened than peripheral collisions. The integrated luminosities used in the dimuon measurement are 26 pb−1 for the pp data and 0.49 nb−1 for the Pb+Pb data. In ultra-relativistic heavy-ion collisions, dilepton pairs may be produced through the interaction of the large electromagnetic fields of the nuclei. A measurement of γγ → μ+μ− in inclusive Pb+Pb collisions at √sNN = 5.02 TeV using 0.49 nb−1 is presented in this thesis. The contribution from background sources of dimuons is removed using a template fit method. The angular and transverse momentum correlations between the muons are measured as a function of collision centrality. In peripheral collisions, the muons exhibit a strong back-to-back correlation consistent with previous measurements of dimuon production in ultra-peripheral collisions. The correlations are observed to broaden significantly in central collisions. The modifications are qualitatively consistent with attenuation of the muons while passing through the hot matter produced in the collision.

Yeung Chi-wang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 128-144). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgement --- p.vi / Contents --- p.vii / List of Figures --- p.xi / List of Tables --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Literature review --- p.3 / Chapter 2.1 --- Nutritional facts of fish --- p.3 / Chapter 2.2 --- Aroma of fish --- p.5 / Chapter 2.2.1 --- Carbonyls and alcohols --- p.6 / Chapter 2.2.2 --- Sulphur-containing compounds --- p.7 / Chapter 2.2.3 --- Bromophenols --- p.9 / Chapter 2.2.4 --- Hydrocarbons --- p.9 / Chapter 2.2.5 --- Off flavor in fish --- p.9 / Chapter 2.2.6 --- Autoxidation of fish meat --- p.10 / Chapter 2.2.7 --- (Z)-4-heptenal in cooked and stored fish --- p.10 / Chapter 2.2.8 --- Volatile acids --- p.11 / Chapter 2.3 --- Salted-dried fish in Hong Kong --- p.11 / Chapter 2.3.1 --- Salted-dried fish used in this study --- p.13 / Chapter 2.3.2 --- Salting methods of the salted-dried fish used in this study --- p.14 / Chapter 2.3.3 --- Salting method used in Tai O --- p.15 / Chapter 2.4 --- Aroma analysis --- p.19 / Chapter 2.4.1 --- Extraction methods --- p.19 / Chapter 2.4.1.1 --- Steam distillation methods --- p.20 / Chapter 2.4.1.2 --- Solvent extraction methods --- p.22 / Chapter 2.4.1.3 --- Headspace methods --- p.22 / Chapter 2.4.2 --- Screening of important aroma contributing volatile compounds --- p.23 / Chapter 2.5 --- Overview --- p.26 / Chapter Chapter 3 --- Method Development --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Methodology --- p.29 / Chapter 3.2.1 --- Reproducibility of injection mode --- p.29 / Chapter 3.2.2 --- Optimization of the sample preparation procedure --- p.29 / Chapter 3.2.3 --- Gas chromatography-mass spectrometry coupled with cooled injection system (GC-MS-CIS) --- p.30 / Chapter 3.3 --- Results and discussion --- p.31 / Chapter 3.3.1 --- Reproducibility of the cooled injection system --- p.31 / Chapter 3.3.2 --- Efficiency of different injection modes --- p.33 / Chapter 3.3.3 --- Optimal equilibrium Time --- p.33 / Chapter 3.3.4 --- Conclusion --- p.37 / Chapter Chapter 4 --- Volatile compounds in the headspace of salted-dried fish --- p.38 / Chapter 4.1 --- Introduction --- p.38 / Chapter 4.2 --- Materials and Methods --- p.39 / Chapter 4.2.1 --- Sample preparation --- p.39 / Chapter 4.2.2 --- Headspace analysis and gas chromatography-mass spectrometry (GC-MS) --- p.42 / Chapter 4.2.3 --- "Identification, quantification and odor activity values (OAV) of compounds" --- p.43 / Chapter 4.2.4 --- Statistical analysis --- p.44 / Chapter 4.3 --- Results and discussion --- p.45 / Chapter 4.3.1 --- Headspace profiles of three salted-dried fishes in Hong Kong --- p.45 / Chapter 4.3.1.1 --- Aldehydes and alcohols --- p.63 / Chapter 4.3.1.2 --- Hydrocarbons and ketones --- p.66 / Chapter 4.3.1.3 --- Nitrogen- (N-)containing and sulfur- (S-)containing compounds --- p.68 / Chapter 4.3.1.4 --- "Esters, furans and pyrazines" --- p.72 / Chapter 4.3.1.5 --- "Acids, pyrroles and pyridine" --- p.73 / Chapter 4.3.1.6 --- Important aroma contributing compounds in salted-dried fish --- p.74 / Chapter 4.3.2 --- Influence of steaming on the salted-dried fish headspace --- p.75 / Chapter 4.3.3 --- Difference in the headspace of salted-dried fish purchased between the first and second year --- p.76 / Chapter 4.3.4 --- Influence of salting methods on the salted-dried fish aroma --- p.76 / Chapter 4.3.5 --- Difference between salted-dried fish purchased at Sai Wan and Tai O --- p.78 / Chapter 4.3.6 --- Difference between salted-dried fish produced from difference fish species --- p.78 / Chapter 4.4 --- Conclusion --- p.79 / Chapter Chapter 5 --- Aroma active compounds in salted-dried fish --- p.81 / Chapter 5.1 --- Introduction --- p.81 / Chapter 5.2 --- Materials and Methods --- p.82 / Chapter 5.2.1 --- Sample preparation --- p.82 / Chapter 5.2.2 --- Gas chromatography static headspace analysis and olfactometry GC-SHA-O and aroma extract dilution analysis (AEDA) --- p.84 / Chapter 5.2.3 --- Compound identification --- p.85 / Chapter 5.2.4 --- Calculation of flavor dilution (FD) factor --- p.85 / Chapter 5.3 --- Results and discussion --- p.86 / Chapter 5.3.1 --- Aroma active compounds in salted-dried fish --- p.86 / Chapter 5.3.1.1 --- Strong and Potent aromas --- p.87 / Chapter 5.3.1.2 --- Roasted aromatic aromas --- p.94 / Chapter 5.3.1.3 --- Floral aromas --- p.95 / Chapter 5.3.1.4 --- Vegetative aromas --- p.96 / Chapter 5.3.1.5 --- Penetrating aromas --- p.97 / Chapter 5.3.1.6 --- Common aromas --- p.98 / Chapter 5.3.2 --- Characteristic of aroma active compounds between steamed and non-steamed salted-dried fish --- p.99 / Chapter 5.3.3 --- Differences in aroma active compounds between regular and delayed salted-dried fish --- p.100 / Chapter 5.3.4 --- Characteristic aroma of different species of salted-dried fish --- p.105 / Chapter 5.3.5 --- Characteristic aroma of salted-dried fish purchased at Sai Wan and Tai O --- p.108 / Chapter 5.3.6 --- Characteristic aroma of salted-dried fish purchased in 2001 and 2002 --- p.108 / Chapter 5.4 --- Conclusion --- p.108 / Chapter Chapter 6 --- Important volatile compounds in salted-dried fish --- p.112 / Chapter 6.1 --- Comparison between OAV and SHA-O --- p.112 / Chapter 6.2 --- Overall conclusion --- p.114 / Chapter 6.2.1 --- Effects of steaming on salted-dried fish aroma --- p.114 / Chapter 6.2.2 --- Effects of salting methods on salted-dried fish aroma --- p.117 / Chapter 6.2.3 --- Characteristics aroma of salted-dried fish prepared from different fish species --- p.120 / Chapter 6.2.4 --- Characteristics aroma of salted-dried fish purchased from different locations --- p.120 / Chapter 6.2.5 --- Characteristics aroma of salted-dried fish purchased from different periods --- p.125 / References --- p.128 / Appendix --- p.145

In this thesis we present three distinct contributions to the study of light flavor physics using the techniques of lattice QCD. These results are arranged into four self-contained papers. The first two papers concern global fits of the quark mass, lattice spacing, and finite volume dependence of the pseudoscalar meson masses and decay constants, computed in a series of lattice QCD simulations, to partially quenched SU(2) and SU(3) chiral perturbation theory (χPT). These fits determine a subset of the low energy constants of chiral perturbation theory — in some cases with increased precision, and in other cases for the first time — which, once determined, can be used to compute other observables and amplitudes in χPT. We also use our formalism to self-consistently probe the behavior of the (asymptotic) chiral expansion as a function of the quark masses by repeating the fits with different subsets of the data. The third paper concerns the first lattice QCD calculation of the semileptonic K0 → π −` +ν` (K`3) form factor at vanishing momentum transfer, f Kπ + (0), with physical mass domain wall quarks. The value of this form factor can be combined with a Standard Model analysis of the experimentally measured K0 → π −` +ν` decay rate to extract a precise value of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element Vus, and to test unitarity of the CKM matrix. We also discuss lattice calculations of the pion and kaon decay constants, which can be used to extract Vud through an analogous Standard Model analysis of experimental constraints on leptonic pion and kaon decays. The final paper explores the recently proposed exact one flavor algorithm (EOFA). This algorithm has been shown to drastically reduce the memory footprint required to simulate single quark flavors on the lattice relative to the widely used rational hybrid Monte Carlo (RHMC) algorithm, while also offering modest O(20%) speed-ups. We independently derive the exact one flavor action, explore its equivalence to the RHMC action, and demonstrate that additional preconditioning techniques can be used to significantly accelerate EOFA simulations. We apply EOFA to the ongoing RBC/UKQCD calculation of the ∆I = 1/2 K → ππ decay amplitude, and demonstrate that, in this context, gauge field configurations can be generated a factor of 4.2 times faster using an EOFAbased simulation rather than the previous RHMC-based simulations. We expect that EOFA will help to significantly reduce the statistical error in the first-principles determination of the Standard Model CP-violation parameters ε and ε′ offered by the K → ππ calculation.

An assay for catheptic activity of lamb gastric tissue extract has been proposed which involves the use of a pH 3.5 hemoglobin substrate following activation of zymogens at pH 2.0, 25C for 30 min.; and inactivation at pH 8.0, 40C for 30 min thereby eliminating the effects of pepsin and rennin. Cathepsin was isolated and purified by ammonium sulfate fractionation, acetone precipitation and gel viii filtration. The purified cathepsin represented approximately 50 fold increase in specific activity over the original extract and a recovery of 15% of the original activity. Degree of purity was monitored by isoelectric focusing in polyacrylamide gels. Some characteristics of the cathepsin were determined. The purified cathepsin hydrolyzed urea-denatured hemoglobin readily at pH 3.5, but it had no activity on substrates specific for cathepsins A, B or c. a-N-benzoyloxycarbonyl- L-gutamyl-L-tyrosine, a-N-benzoyl-L-argininamide hydrochloride and a-N-acetyl-L-tyrosinamide. Approximate isoelectric point was pH 5.6. The purified enzyme was similar to cathepsin D. Parmesan, Romano, and Cheddar cheese manufactured with lamb pregastric esterase and gastric extracts added to the curd or milk were superior in flavor when both were employed, and either extract alone made better cheese than the uninoculated control.

The flora of Aotearoa/ New Zealand has evolved in association with birds and lizards as the dominant frugivores and seed dispersers. There is a wide range of ripe fruit colours within the native fleshy-fruited plants spanning the visible light spectrum from red to violet, with the notable exception of green. The evolution of fleshy-fruit and fruiting related trait, may be a result of the selection pressures exerted by different frugivore guilds. This study was conducted to ascertain if endemic diurnal lizards, Oligosoma species (Scincidae: Lacertilia), display features associated with visual based foraging, colour sensitivity and colour preferences, which are necessary conditions to infer a co-evolutionary mutualism between fleshy-fruited plant species and lizards as seed dispersers, which may have influenced the evolution of fruit colour. Many lizards have exceptional colour vision, with the ability to see a wide range of the visual light spectrum from short wave ultra violet to long wave red. They are able to discriminate all aspects of colour: hue, brightness and saturation. Fruit colour within Coprosma (Rubiaceae), is extremely variable, between and within species. The study of fruit colour preferences within this genus and particularly within species with polymorphic fruit colour provides a valuable comparison of frugivore preference to fruit with little inter and intraspecific variation, therefore minimising potentially confounding factors due to phylogeny. Fruit-colour choice experiments were conducted offering fruit from two colour categories based on postulated frugivore preferences; red and red orange fruit has been associated with avian frugivores whilst white and pale fruit has been associated with lizard frugivory in New Zealand. Experiments were conducted both ex-situ, in environmentally controlled laboratories and in-situ at Macraes Flat, Otago. Pilot trials indicated that the background colour on which fruit were presented was important in fruit choice and consequentially, all fruit were offered on a background which provided contrast to both fruit colour categories. The laboratory trials showed some weak evidence for a preference of white and pale blue fruit however, in-situ trials showed a strong preference for white over red fruit. Field studies were conducted to ascertain the composition of fleshy-fruit in the diets of lizards and the results were consistent with those expected for a generalist omnivore; many of the small fruits available to lizards were consumed however, the results indicated that plant abundance does not adequately explain fruit consumption at this field site. A preference index showed that white and pale fruited plants, Melicytus alpinus and Coprosma spp., were preferred over more abundant orange and red fruited plants. Fruit odour was investigated to determine if fruit choice was mediated primarily by visual cues as opposed to odour cues. Fruit choice trials with the fruit concealed from view indicated that fruit choice was based primarily on visual cues in Oligosoma skinks. It is concluded that lizards demonstrate the necessary conditions to infer that as frugivores, they may have influenced the evolution of fruit colour and that within the open habitats of Aotearoa/ New Zealand, the shrubs, particularly the divaricate shrubs may have provided sufficient environmental conditions to establish a mutualism between plants and lizards resulting in the evolution of small, white and other low chroma fruits.

Freshness is a holistic attribute of a food product, with a meaning that most often includes how recently produced or harvested a food currently is and to what extent it has been preserved. Without knowledge of production date, consumers will judge perceived freshness by the sensory properties of foods. However, these properties are not easily identified and described, as they vary considerably between different product types. The objective of this thesis, was to determine the sensory properties that consumers most associate with baked product freshness, and to determine the volatile composition responsible for "fresh-baked" flavour. In addition, relationships were determined and modelled between volatile composition, sensory properties and perceived freshness, in order to predict perceived freshness without the need for further consumer testing. Two consumer studies were carried, where perceived freshness of 10 breads, 5 cakes and 5 biscuits was measured based on appearance, flavour and texture, and by product odour only. Individual differences in perceived freshness were represented on two-dimensional Freshness Maps generated using Principal Component Analysis (PCA). Consumers used similar terms to describe product freshness, but different terms were associated with specific product types. An understanding of the sensory characteristics associated with perceived freshness was determined by examining relationships between perceived freshness and descriptive analysis (DA). Sensory characteristics perceived to convey freshness in one product type did not necessarily convey freshness in another. Further relationships between perceived freshness and sensory characteristics were determined for 20 bread types. Descriptive analysis was carried out with all breads, whereas perceived freshness was measured for 10 of these. Three consumer clusters were identified that were homogenous in their freshness perceptions, indicating that perceived bread freshness varied among consumers. Perceived freshness of breads not evaluated by consumers, but assessed by descriptive sensory analysis, were predicted for each consumer cluster using Partial Least Squares Regression (PLSR). Most fresh breads were described as having "porous" appearance, "floury", "toasted" and "malty" odour, "sweet", "buttery", and "oily" flavour, and "sweet" aftertaste. Least fresh breads were described as "musty" odour, "sour" flavour and "sour" aftertaste. In addition, Proton Transfer Reaction Mass Spectrometry (PTR-MS) measured the volatile composition of all 20 bread types. Thirty-three mass ions significantly discriminated between bread types. Relationships were determined between odour and flavour sensory attributes, and mass spectral data using 15 of the 20 breads. PLSR models predicted the sensory properties and perceived freshness of all breads including five types not included in the construction of models. Bread perceived to be most fresh shared a similar combination of positively correlated mass ions, m/z 87, 97 and 117, also represented by "dairy" odour and "buttery" flavour, whilst the masses m/z 63, 69 and 91 were negatively associated with bread freshness, represented by the sensory attributes "grain", and "musty" odour, and "sour" flavour. The influence of sweetener, fat type and time from baking on perceived freshness was determined for cakes. Four sweeteners (sucrose, glucose, xylitol, isomaltose), three fat types (butter, margarine, shortening) and two times from baking (days zero and 15) were investigated. Descriptive analysis was carried out using a trained panel, and volatile composition of measured using PTR-MS. Twelve cake samples with the largest sensory variation were further selected for consumer testing for perceived freshness. Results demonstrated that sweetener type, fat type, time from baking and their interaction significantly influenced the sensory properties, volatile composition, and perceived freshness of cakes. There was no evidence of perceived freshness segmentation among consumers. Perceived freshness of the twelve cakes not evaluated by consumers was predicted using sensory properties, volatile composition, and their combination. The freshest cakes were evaluated on the day of baking, and contained a combination of margarine and sucrose, and butter and sucrose. The least fresh cakes were evaluated after 15 days of storage and contained a combination of shortening and isomaltose, and butter and isomaltose. The most fresh samples were positively correlated with mass ions m/z 124, 74, 97 and 93, and sensory characteristics of "buttery" odour, and "buttery", "eggy" flavour. The least fresh samples were negatively correlated with mass ions m/z 110 and 95, and sensory characteristics of "rancid", "dusty" and "fatty" odour. Best predictions were obtained for cakes evaluated on day zero that contained a combination of shortening and sucrose. This research established an objective knowledge of consumers' perceived freshness of baked product types in terms of sensory properties and volatile composition. This approach enabled the understanding of ingredients and time from baking influences, as well their interaction on baked product freshness. The predictive models developed that examined relationships between PTR-MS spectra, sensory characteristics and consumer perceived freshness can be applied to predict freshness of baked products not assessed by consumers.

Hops (Humulus lupulus L.) are primarily used to provide specific characteristics to beer, such as bitterness, aroma, flavor, and microbial stability. The chemical composition of hops, relative to how they are used during the brewing process, dictates the expression of these characteristics. Of the raw ingredients that go into making beer, hops are perhaps the most costly. Considerable resources are required to grow quality hops, and therefore, brewers and hop growers alike have a common goal of obtaining the highest quality hops possible. However, quality can be a relative term. While it is commonly agreed upon that high brewing values, such as α-acids and essential oil content, and robust structural integrity are indicators of quality hops, there are many opinions of the ideal aroma. Changes in the chemical composition of hops during plant maturation are a dynamic process requiring a comprehensive, in-depth chemical and sensory analysis in order to maximize the characteristics of interest to brewers. The complex aroma chemistry associated with hops in beer has been a confounding variable for the practical brewer, and a deeper understanding of hop aroma development during cultivation is needed. The effect of harvest date, location, and cultivar on key chemical components of Willamette and Cascade hops was investigated for the 2010 and 2011 growing seasons. Hops were harvested at 3 time points (Early, Typical, and Late), within a 3-week interval from 2 different farms in the Willamette Valley, Oregon. A split-plot experimental design for each cultivar was used; each farm represented a main plot and harvest years were designated as subplots. American Society of Brewing Chemist standard methods of analysis were used to measure moisture content, hop acids and their homologs, Hop Storage Index, total essential oil content and volatile profile by GC-FID. Additionally, difference testing, descriptive analysis, and consumer acceptance testing was conducted using beers brewed with either Typical or Late harvested Cascade hops from the 2010 harvest year. The response of analytes was dependent on the cultivar being examined, its location within the Willamette Valley, as well as days until harvest. Hop acids did not change appreciably during plant maturation for the period examined, while hop oil content increased hyperbolically to a plateau as the hops aged on the bine. Increases in oil quantity were strongly correlated (r > 0.90) with increases in α-pinene, β-pinene, myrcene, limonene, methyl heptanoate, and linalool concentrations. For Cascade, α-pinene, β-pinene, myrcene, limonene, ρ-cymene, caryophyllene, E, β-farnesene, and humulene all increased from Early to Typical points but no increase was observed between the Typical and Late time point. Linalool and methyl heptanoate increased between each time point while citral and humulene epoxide differed between Early harvest and Late harvest, but not between Early and Typical or Late and Typical harvests. For Willamette hops, α-pinene, β-pinene, myrcene, limonene, ρ-cymene, and linalool all increased between each time point. Caryophyllene, E β-farnesene, humulene, farnesol and citral all increased from Early harvest to Typical harvest but no difference was observed between Typical and Late. Clear sensory differences were found between beers brewed with Typical harvest Cascade hops and Late harvest Cascade hops, in terms of difference testing, descriptive analysis and consumer preference tests. / Graduation date: 2013