The incidence of type 2 diabetes is considered an epidemic in Western countries, and its prevalence is more common in the Hispanic population than in non-Hispanic whites. Postprandial hyperglycemia has been associated with oxidative stress (OS), thus; reducing postprandial glycemia and/or OS through dietary consumption of resistant starch (RS) may be one approach to help modulate glucose and insulin responses. The purpose of this study was twofold: 1) to evaluate the physicochemical and sensory properties of cereal food products supplemented with RS. 2) to compare the effects of a single ingestion of granola bars with high (~18 grams of RS) and low (~0 grams of RS) RS compositions on the postprandial glucose and insulin responses (n=14) and oxidative stress parameters (cellular glutathione peroxidase, F2- isoprostanes, and oxygen radical absorbance capacity) in Hispanic women (n=9). Granola bars and cereals were developed to provide 2 levels (10% and 15%) of RS; isocaloric (0% RS) control samples were prepared with readily digestible (high amylopectin) starch. Samples were stored for up to 4 weeks at 20 °C. Mean composition of the high RS granola bars was 6% protein, 15% moisture, and 18% lipid. RS levels slightly increased from 14 to 16 g/serving after 4 weeks of storage, supporting published research that RS increases with storage due to retrogradation and crystallization of amylose chains. Color became lighter as the level of RS increased (p<0.001). Granola bars containing RS were less brittle (p=0.0043) than control granola bars. Sensory results indicated granola bars/cereals were acceptable. RS-supplemented granola bars were then used for the evaluation of RS ingestion in humans. There was no difference in postprandial glucose and insulin responses after a single ingestion of a RS-supplemented (18 g) granola bar. No differences were found in the oxidative stress parameters measured. In a subgroup of subjects (n=9), a lower glucose response 30 minutes after RS consumption was found (p=0.0496). Thus, RS consumption may lower fluctuations in blood glucose, which may help manage glucose levels in individuals at risk of type 2 diabetes. Further studies of short term RS consumption are warranted to elucidate its benefits in glucose management. / Ph. D.

Fruits and vegetables are highly perishable, produced seasonally, and large quantities (about 50-60% of production) are wasted during high season due to poor handling and lack of cold storage in Tanzania. Processing excess pineapple into vinegar which can be used for preservation of other fruits and vegetables may be a helpful strategy for reducing losses. Vinegar was produced from pineapple juice supplemented with sugar to produce different degrees of Brix (13, 20 and 30) and was fermented with Saccharomyces cereviciae, Acetobacter pasteurianus, and Gluconobacter oxydans. Levels of acetic acid were measured in the vinegar produced. High production (5.8%) of acetic acid was observed with pineapple juice concentrated to 130 Brix with the combination of Saccharomyces cerevisiae, A. pasteurianus and G. oxydans. The pineapple vinegar produced was used for preservation of carrot and mango. The pH of carrot pickle and mango chutney was monitored for three months. The pH of preserved carrot and mango was below 4 and no significant changes in pH were observed during three months storage at 29-320C. Chemical analysis of vitamin A and vitamin C showed high losses of Vitamin A in carrot and increased vitamin A in mango, but losses of about 74% and 85% of vitamin C were observed in carrot and mango after processing. Consumer sensory testing of pineapple vinegar, carrot pickle and mango chutney showed no significance different on overall consumer acceptability of products during storage. Pineapple vinegar can be used to rescue mango and carrots that would otherwise be lost, producing highly acceptable food products in Tanzania. / Master of Science in Life Sciences

The relationships between volatile flavor compounds, sensory descriptors and consumer acceptability were determined for eight commercial American dry-cured hams using external preference and flavor mapping. The majority of consumers preferred (p<0.05) hams that had more intense caramelized, smoky, savory and molasses aromas as well as more intense sweet and savory flavors. Sixteen aroma impact compounds were identified from the headspace volatiles of dry-cured hams. The consumers with the highest acceptability scores preferred (p<0.05) hams that were characterized by 4-methyl-2-methoxyphenol (sweet ham), 4-ethyl-2-methoxyphenol (sweet ham), 2-methoxyphenol (smoky, cocoa), 2,6-dimethoxyphenol (smoky ham, savory) and 2uranmethanol (burnt meat, vitamin). Fourteen percent of consumers preferred (p<0.05) two hams that were characterized by methional (baked potato). Consumer acceptability scores were lower for hams either characterized by methanethiol (sulfur), carbon disulfide (sulfur), 2-butanone (sweet), 3-methylbutanal (malty, fermented), 2-heptanone (burnt meat, vitamin), hexanal (cut grass), benzeneacetaldehyde (floral), 1-octen-3-ol (mushroom) or characterized by benzaldehyde (burnt meat, cooked meat) and limonene (citrus).

Flaxseed is an excellent source of bioactive compounds, alpha-linolenic acid (ALA) and secoisolariciresinol diglucoside (SDG), which when added to food products enhance their functionality. However, when flaxseed is added to foods, overall acceptability and sensory properties can be affected, which may negatively affect the role of functional food in providing health benefits. This study was designed to determine the effects of adding milled flaxseeds (20g or 30g) and storage (1 month and 6 months) at - 200C in banana and cinnamon muffins on the sensory properties of muffins using both consumer acceptability evaluation and descriptive analysis, physical and chemical measurements, and ALA and SDG concentrations. Results were correlated using partial least square (PLS) to provide an explicit demonstration of association between overall acceptability of muffins and results from various measurements conducted. It was revealed that the addition of flaxseed reduced overall acceptability due to the enhancement of flax aroma and flavor, oil aroma and flavor, sour aroma and taste, brown color, and firmness., while storage had no impact. The negative influence of these sensory attributes was addressed by the addition of flavorings. Cinnamon flavoring reduced the presence of oil aroma and flavor, and sour aroma and taste while firmness decreased when pureed banana was added. But the intensities of flax aroma and flavor, and brown color were still pronounced in muffins even after the addition of the two flavorings. ALA and SDG concentrations were markedly increased in muffins when flaxseed was added. Storage did not significantly affect the levels of ALA in all muffins but prolonged storage increased SDG level, which can be associated with its role in enhancing extraction proficiency of SDG from the muffin matrix. Although results revealed that acceptability of muffins was significantly higher among clinical trial participants, the mean liking values had moderate deviation between consumers and clinical trial participants. This indicated that muffins fortified with flaxseeds can be acceptable by consumers with diverse wants. / May 2016

This study examined the effects of wet aging on water-soluble flavor compounds, descriptive flavor, consumer acceptability, and willingness-to-pay of beef strip steaks. Twenty USDA Select boneless beef loins (NAMP #180) were dorsally divided into four equal portions, which were randomized to receive either 0, 7, 14, or 21 d of wet aging. Short-chained peptide concentration increased from 4.11 mg/g on d 0 to 5.12 mg/g on d 7 (P = 0.011) and subsequently increased to 7.14 mg/g on d 21 (P < 0.001). Cooked beef contained 1.85 mg/g less short-chained peptides than raw beef (P < 0.001). Wet aging for 21 d increased the concentrations of amino acids, which are precursors for the Maillard reaction, including methionine, threonine, cystine, serine, tryptophan, and phenylalanine (P < 0.001). Wet aging decreased the nucleotide concentrations (P ≤ 0.003) and increased hypoxanthine concentration, a compound that imparts bitter flavor (P < 0.001). Flavor intensity of steaks was greater on d 14 than on d 21 (P = 0.009). Steaks that were not aged (d 0) had a more intense umami taste than those aged for 7 and 21 d (P ≤ 0.042); whereas d 7 steaks had less off-flavor, described as metallic, oxidized, and cardboard, than steaks from other aging treatments (P ≤ 0.038). Demand analysis indicated that 14-d steaks would be sold at 5.2, 5.2, and 6.7 units (0.454kg/unit) less (P < 0.001) than steaks aged for 0, 7, and 21 d if holding price constant at $14/0.454kg. Wet aging alters the content of water-soluble flavor compounds in beef, which contributes to flavor development during cooking. Wet aging for 21 d decreased umami taste and flavor intensity. However, amino acid concentrations increased during aging, which contributes to meaty and browning flavors that may be more prevalent in other direct heating methods such as grilling. In addition, results indicated that wet aging for 14 d was not sufficient to provide the flavor and tenderness improvements that were apparent after 21 d of aging since aging beef for 14 d decreased consumer acceptance and demand.

For water suppliers, using chlorine is necessary to ensure water bacteriological quality from the treatment plant to the consumers' tap. However, chlorine flavour is one of the most common reasons advocated for choosing tap water alternatives as drinking water. As a consequence, the putative link between chlorine flavour perception and tap water consumption is an issue in drinking water habits studies. Since the sensory mechanisms involved in chlorine flavour perception remained largely unknown, the main objective of this thesis work was to first highlight those mechanisms and then to identify potential lever chlorine flavour sensory neutralisation.In a first step, we demonstrated that hypochlorous acid associated, which is likelyresponsible of chlorine flavour in tap water, could activate the olfactory system at low concentrations and the trigeminal system for concentrations up to 4 mg/L Cl2. Additionally, our results suggested that tap water consumption does not seem to be related to sensitivity to chlorine flavour but rather to consumers' tap water representation.In a second stage, we explored the impact of water mineral matrix on chlorine flavour perception. We demonstrated first that water molarity and cationic content variations modulate drinking water taste. We also evidenced that chlorine flavour intensity is modulated according to water composition. Nevertheless, our data suggest that physico-chemical, in- mouth physiological and sensory mechanisms are likely involved in such modulation.In the last part of the Thesis work, we investigate the putative influence of aroma perceptionon chlorine flavour. Our results showed that beyond chemical reactions between hypochlorous acid and odorants, aromas at peri-threshold concentration enhance chlorine flavour and decrease tap water acceptability

Pour les distributeurs d’eau, l’utilisation de chlore permet d’assurer la qualité bactériologique de l’eau, de l’usine de traitement au robinet du consommateur. Cependant, la flaveur chlore constitue une des plaintes les plus importantes adressée à l’encontre de l’eau du robinet et constitue donc un enjeu majeur de satisfaction des consommateurs. Dans ce contexte, l’objectif des travaux engagés dans cette thèse a été de mettre en évidence des moyens potentiels de neutralisation sensorielle de la flaveur chlore dans l’eau. Néanmoins, les mécanismes impliqués dans la perception de cette flaveur étant largement méconnu, notre première étape a consisté à préciser la nature de ces mécanismes. Nos résultats ont ainsi mis en évidence que l’acide hypochloreux sous sa forme associée, qui est le stimulus supposé de la flaveur chlore dans l’eau, active le système olfactif à faibles concentrations et le système trigéminal à partir de 4 mg/L. De plus, nous avons observé que la consommation d’eau du robinet ne semble pas liée à la sensibilité au chlore mais plutôt à la représentation qu’ont les consommateurs de l’eau du robinet. Dans un deuxième temps, nous avons exploré le rôle de la matrice de l’eau dans la perception de la flaveur chlore. Nous avons d’abord montré que les variations de molarité et de composition en cations de l’eau modulent le goût de l’eau. Nous avons ensuite mis en évidence une modulation de l’intensité chlorée en fonction de la matrice minérale de l’eau. Cependant, nos données suggèrent l’existence de mécanismes multiples, physicochimiques, physiologiques en bouche et sensoriels, susceptibles de moduler la perception de la flaveur chlore. Enfin, nous avons exploré les interactions perceptives entre un arôme supposé neutralisant et ajouté à l’eau de boisson et la flaveur chlore. Nos résultats montrent que l’ajout d’un arôme à un niveau péri-liminaire augmente la perception de la flaveur chlore et diminue l’acceptabilité des consommateurs. A plus forte concentrations, certains arômes semblent capables de diminuer la perception du chlore, mais ces conditions sont incompatibles avec les contraintes liées à l’eau de distribution / For water suppliers, using chlorine is necessary to ensure water bacteriological quality from the treatment plant to the consumers’ tap. However, chlorine flavour is one of the most common reasons advocated for choosing tap water alternatives as drinking water. As a consequence, the putative link between chlorine flavour perception and tap water consumption is an issue in drinking water habits studies. Since the sensory mechanisms involved in chlorine flavour perception remained largely unknown, the main objective of this thesis work was to first highlight those mechanisms and then to identify potential lever chlorine flavour sensory neutralisation.In a first step, we demonstrated that hypochlorous acid associated, which is likelyresponsible of chlorine flavour in tap water, could activate the olfactory system at low concentrations and the trigeminal system for concentrations up to 4 mg/L Cl2. Additionally, our results suggested that tap water consumption does not seem to be related to sensitivity to chlorine flavour but rather to consumers’ tap water representation.In a second stage, we explored the impact of water mineral matrix on chlorine flavour perception. We demonstrated first that water molarity and cationic content variations modulate drinking water taste. We also evidenced that chlorine flavour intensity is modulated according to water composition. Nevertheless, our data suggest that physico-chemical, in- mouth physiological and sensory mechanisms are likely involved in such modulation.In the last part of the Thesis work, we investigate the putative influence of aroma perceptionon chlorine flavour. Our results showed that beyond chemical reactions between hypochlorous acid and odorants, aromas at peri-threshold concentration enhance chlorine flavour and decrease tap water acceptability