<p> The research in this thesis investigated the effects of different vitamin C forms [ascorbic acid (Asc), sodium ascorbate, and calcium ascorbate] on gelatinization, pasting, and short-term retrogradation of wheat starch. Vitamin C is the third most supplemented nutrient in the U.S. and necessary for prevention or treatment of many illnesses. Asc is also used in food products as an acidulant that decreases microbial growth and extends shelf-life, flavoring agent that promotes sour taste, and bread improver that increases gluten development and dough strength in wheat doughs. Ascorbate salts are used as vitamin C sources when a sour taste or pH decrease is undesirable. The gelatinization temperature (Tgel) of wheat starch in solutions of the vitamin C forms and related acids and salts at 0.5, 1.0, and 1.5 M concentrations (or equivalent) was measured using a differential scanning calorimeter and, compared to starch in water, was increased by all the salt solutions and decreased only by Asc. Calcium ascorbate increased Tgel more than the other salts due to hydrogen bonds between ascorbate and starch and strong hydration by water of Ca2+ that stabilized the starch-water structure and inhibited gelatinization. Asc decreased starch Tgel while similarly acidic solutions did not because Asc caused more extensive starch hydrolysis, which promoted granule swelling and amylose leaching. The paste viscosity values of wheat starch in solution were measured with a rapid visco analyzer and, compared to starch in water, were increased by all salt solutions except NaCl and increased by all acidic solutions until breakdown, then decreased. Ascorbate salts increased paste viscosities significantly more than chloride salts due to the stabilization effect of ascorbate hydrogen bonds that increased the amount of larger starch structures, which increased the viscosity during pasting and short-term amylose retrogradation. Ascorbate-containing acidic solutions increased starch peak viscosity and decreased trough and final viscosities more than HCl because increased granular swelling and amylose leaching results in a more rapid and greater initial increase in viscosity and subsequent decrease in viscosity when granular breakdown overtakes swelling. The results of this work could be used by food researchers and product developers to supplement or fortify vitamin C in a starch-based food and/or modify the functions of starch within that food.  </p>

Due to their resilience, durability, and broad genetic variations, increasing the production and consumption of landrace cereals has been highlighted as a solution to handle increasing environmental variability resulting from climate change. However, the consumption of landrace cereals remains low due to limited production and purchase availability for consumers. To increase knowledge and possibly the production and consumption of landrace cereals, the overall aim of the study was to investigate the influence of terroir and the addition of ingredients on consumers' perception and acceptance of sensory qualities in cookies prepared from the landrace cereal swidden rye. Rye (Secale cereale) has been pointed out as a wonder crop and is of historical importance in the Nordic region. The study analyses the application of swidden rye (Swedish: Svedjeråg), a landrace variety of rye, in cookies by investigating how consumers perceive and describe its sensory characteristics. Additionally, the study explores how terroir relates to sensory perceptions. Five samples of swidden rye and a conventional rye sample have been included in the study. The study used a mixed methods approach with a Quantitative Descriptive Analysis (QDA®), a hedonic liking test, a focus group, and Geographical Information Systems (GIS) data. Different sensory profiles could be detected for the cookies produced with swidden rye, and a descriptive vocabulary and sensory profiles have been developed to describe the swidden rye cookies. Common descriptors were a browned butter aroma, a colour that ranged between golden and grey, roasted nutty and rye flavours, with a coarser or oily texture. All cookies were considered liked and acceptable by consumers, and cookies produced with swidden rye and the addition of butter and sugar could meet future consumers' expectations. There were relationships between terroir and sensory perceptions of swidden rye cookies. Relationships were found for increases and decreases in intensities of different sensory attributes. The geographical location on the latitude was only related to a decrease in the liking for texture; otherwise, differences in the consumer's liking were not related to the farm's geographical location. Showing that soil texture and land types are more related to differences in consumer liking and that the geographical location was less so. However, all parameters representing terroir were related to perceived sensory attribute intensities. The knowledge gained can be applied in the efforts to increase the production and consumption of landrace cereals. Communicating both the history, the historical importance, and the different sensory characteristics of swidden rye through terroir could be one way to increase consumers' interests and consumption.

<p>  </p> <p>Edible insects, a novel source of protein, are gaining interest for their health promoting attributes. In this study, the <em>in vivo and in vitro</em> antioxidant effect of tropical banded cricket (<em>Gryllodes sigillatus</em>) peptides was evaluated. Antioxidant activity by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activity, oxygen radical antioxidant capacity (ORAC) and caco-2 cellular antioxidant activity, were measured in hydrolyzed followed by simulated gastrointestinal digested (SGD) cricket peptides. <em>In vivo</em> analysis was conducted using <em>Caenorhabditis elegans</em> as a model. <em>In vitro</em> analysis showed cricket peptides had greater (p< 0.05) antioxidant activity than the unhydrolyzed protein (control). In <em>C. elegans,</em> the lifespan of nematodes fed SGD peptides increased under chronic and acute oxidative stress conditions. Reactive oxygen species (ROS) levels of nematodes fed SGD peptides under paraquat induced oxidative stress were lower (p<0.05) than that of the control group. Further studies using polymerase chain reaction (PCR) indicated that the increased resistance to oxidative stress in <em>C. elegans</em> fed SGD peptides could be due to the increased expression of the stress-related gene gst-4. Taken together, these results indicate that tropical banded cricket peptides could be used as a functional food and nutraceutical to combat oxidative stress. </p>

Cluster thinning, leaf removal and kaolin application are three commonly employed means of modifying fruit zone microclimates assumed to improve grape and wine quality. High labour costs in addition to the potential for location and varietal-specific responses make the benefits of these practices equivocal. To explore this question, I employed a stratified random block design in two Vancouver Island commercial vineyards where Pinot gris vines were manipulated with one of four experimental treatments: control, cluster thinning to one cluster per shoot, heavy leaf removal with a Kaolin clay application, or a combined heavy leaf removal – cluster thinning - Kaolin treatment. The resulting wines were subjected to detailed sensory evaluations, consumer valuation, and a cost-benefit analysis to determine their respective return-on-investment. Results indicate that despite apparent sensory changes driven by vineyard treatments, the lack of any perceived added value suggests that regional producers of Pinot gris should avoid using the assessed treatments as strategies to increase wine quality. The cost-benefit analysis revealed that heavy leaf removal combined with Kaolin clay application may provide a benefit outside of changes to wine quality. The demonstrable improvement in growing conditions under this treatment resulted in a significant decrease in rot pressure. This suggests that the treatment may be a viable option for increasing usable yields of Pinot gris without placing an insurmountable financial cost on the producer. / Graduate

<p>  </p> <p>Sensory perception and acceptance of disliked healthy foods can be improved through strategies such as repeated exposure. Yet, minimal work has investigated whether these approaches are effective in adult populations. Further, for interventions that do demonstrate modifications of perception or acceptance, we lack understanding of the full spectrum of contributing factors influencing the improvement of the sensory experience. For example, animal data suggest that factors such as saliva and salivary proteins are modifiable by diet and play a direct role in the perception of aversive bitter and astringent compounds, but minimal work has verified this in humans. Additionally, we know that there are myriad barriers and facilitators to healthy food consumption, but there are few investigations of these factors related to empirical assessments of liking. The work presented in this dissertation begins to address these gaps using untrained participants within a general student-aged adult population. We tested effects of repeated consumption of a bitter flavanol “tea” on bitterness intensity and salivary protein composition, demonstrating reduced bitterness intensity after repeated oral sensory exposure of the flavanol, with limited alterations in salivary protein composition attributable to flavanol exposure alone. Next, in a separate intervention, we tested the effect of repeated vegetable flavor exposure within a novel exposure matrix on liking of green vegetables. Using a game that challenged players to identify flavors in vegetable flavored gummy candies, we showed that repeated exposure using this method increased liking of initially disliked chopped vegetables. In a subsequent secondary analysis of data collected during this intervention, we identified variables related to sensory perception, food attitudes and behaviors, and other individual factors that explained variation in vegetable liking in ways that were unique between vegetables, underscoring the complexity of liking. Other chapters included in this dissertation accentuate these complexities through a methodological lens, providing evidence that stimuli choice, study population, and questionnaire design can all significantly impact results from sensory evaluations. Overall, repeated exposure is a promising strategy to help alleviate taste-related barriers to healthy eating in adults but is not a one-size-fits-all approach. Future work should investigate the generalizability of these methods in different adult populations and investigate impacts on dietary intake.</p>

<p dir="ltr">Baked goods are one of the primary sources of added sugar in the American diet. Excessive consumption of added sugar can lead to diseases such as obesity, heart disease, and diabetes. As information pertaining to the link between health and diet becomes more available to consumers, the demand for products with lower calories, fat, and sugar continues to rise. The obstacle in formulating baked goods with alternative sweeteners is that these sweeteners have different effects on the physicochemical properties of the starch in the products than that of sucrose, leading to differences in texture, color (browning), texture, and flavor between the sucrose-containing products consumers are accustomed to and the new reduced sugar products. Previous studies done by the Mauer lab have found that interactions between the sweeteners that enter the amorphous region of the starch granule alter physicochemical properties of the starch, including the gelatinization temperature (T_gel) and pasting properties of the starch. The purpose of this project was to investigate how the presence of oligosaccharides (OS) used as sucrose replacers in starch-containing products alters the functionality of the starch through modification of its thermal and physicochemical properties. Different botanical sources of starch were preconditioned in solutions containing different concentrations of select OS, varying temperature during preconditioning. The preconditioned starches were then analyzed by differential scanning calorimetry (DSC), rapid visco analysis (RVA), and x-ray diffraction (XRD). Results demonstrated that several OS are less effective plasticizers of starch (all botanical sources) than sucrose, meaning T_gel is higher in the presence of these OS and less pasting occurs. This is advantageous for formulating low moisture baked goods that rely on inhibition of starch gelatinization for desirable product quality.</p>

No description available.

<p> The inter/intramolecular interactions and associations between constituents determine the microstructure of food and its response to mechanical deformation and flow. The characterization of food rheology enables the design of efficient processing equipment, production of high-quality, stable end products, prediction of textural and sensorial attributes, and assurance of consumer acceptability. Foods are subjected to rapid and large deformations during processing operations and consumption. Dynamic oscillatory shear tests are carried out by subjecting food to a sinusoidal deformation (or stress) and probing the mechanical stress (or strain) and recording the response as a function of time. In the SAOS region, the mechanical response is in the form of a perfect sinusoidal curve and interpretation is straightforward as expected from a linear model. On the other hand, LAOS response requires complex mathematical relations to extract meaningful rheological parameters. In this dissertation, Fourier Transform-Chebyshev Decomposition (FTC) and Sequence of Physical Processes (SPP) methods were utilized to quantify the LAOS response of selected food materials. The objective of this study is to gain new insights into the nonlinear rheology and structural architecture of food materials. To offer insights into the microstructure–rheology relations, rheological measurements were accompanied by various techniques probing chemical interactions (FTIR), imaging (Cryo-SEM, SEM), quantitative network analysis, and molecular size (SDS-PAGE). This dissertation showed that LAOS rheology is highly correlated with the network structure of food shown by the quantitative network analysis utilizing SEM images. It is a powerful tool to detect the effect of small molecules on the nonlinear rheology of food (HMW-LMW glutenin ratio, gliadin for dough, fat content in yogurt, and amylopectin/amylose ratio of starch in a suspension). Nonlinear parameters were sensitive to structural changes occurring in dough structure during processing conditions including aging at room and elevated temperatures. Lastly, the SPP method enabling time-resolved interpretation of nonlinear rheology provided detailed transient microstructural interpretations whereas the FTC method gave static measures at specific strains in an oscillation cycle. Thus, nonlinear rheology of doughs with various gluten subfractions in MAOS and LAOS regions as well as shear thickening characteristic of starch suspensions with changing amylopectin/amylose ratio interpreted by the SPP method gave more sensitive results than the FTC method. The application of fundamental knowledge from this work can be a guide to evaluating the architecture and nonlinear rheology of food for the assurance of consumer acceptancy and the fabrication of efficient machinery by building more accurate mechanical models of complex food systems. </p>

<p>  </p> <p>The research in this dissertation explored the impact of different sugar reducing agents [SRAs: sugars, sugar alcohols, oligosaccharides (OS), and polymers] on the thermal properties of starch (gelatinization, pasting, and retrogradation) and the baking performance of a model baked goods system (wire-cut cookies). The overconsumption of added sugar and underconsumption of dietary fiber have been linked to increased developmental risks for obesity and related diseases, including cardiovascular disease, diabetes, and colorectal cancer. Some SRAs, such as non-digestible oligosaccharides (OS), are considered soluble dietary fiber and could help offset the health detriments from excess sugar and low fiber intake, while also providing similar functionality (texture and structure) to that of sucrose in baked goods systems that rely on the control of phase and state changes in starch. The gelatinization temperature (Tgel) of wheat starch in the presence of SRA solutions at various concentrations (10% to 60% w/w) was measured using differential scanning calorimetry (DSC), and was best explained by SRA plasticization properties [solvent effective volume fraction (<em>feff,w</em>)], solution viscosity, and size (based on the previously proposed starch granule size limit of 1,000 g/mol). The paste viscosity parameters of starch in SRA solutions were measured with a routine rapid visco analyzer (RVA); and were increased in monosaccharide solutions and decreased in 6-carbon sugar alcohol and OS solutions as solution concentration was increased. Differences in starch paste response variables were explained by SRAs either promoting or restricting amylose leaching during heating. The recrystallization of amylopectin over time was promoted in monosaccharide solutions (glucose, fructose, allulose) and in many OS solutions, and was explained in terms of SRA hydrogen bonding interactions with water and/or starch chains. The appearance attributes of wire-cut cookies containing OS were similar to a sucrose control formulation; however, differences were found in cookie texture attributes which were linked to OS effects on solution viscosity and moisture retention during baking. Cookies made with allulose and erythritol were the least similar to the sucrose control across all quality attributes, and therefore these two SRAs would not be recommended as sugar replacers in low-moisture baked goods. The findings from this dissertation could be helpful to food researchers and product developers seeking to reduce or replace added sugars in starch-containing food systems with healthier alternatives.</p>

Combining foods, combining tools. To date, most of the published works that have attempted to relate aroma release and sensory perception are far from mimicking the real consumption context, as assessments often do not consider food oral processing during mastication and are performed on single or model foods. A multidisciplinary approach integrating in vivo aroma release, oral processing behaviour, and dynamic sensory methods is needed to have a better understanding of how the release, evolution, and fading of the flavour of real complex food matrices are being perceived during consumption. The research described in this thesis aims to investigate the relative contributions that food structure and its composition and oral processing behaviour have on aroma release and perception of food matrices made up of different components and contrasting textures, so-called composite foods. Results showed that the processes of aroma release and perception of composite foods are multidimensional phenomena and seem to be modulated by cross-modal texture-aroma interactions. While aroma release increased when a food was assessed in combination with other foods, consumer’s ability to discriminate between foods was reduced and off-flavours and texture deficiencies were masked. Furthermore, the role of oral processing behaviour on the breakdown of the food impacting aroma release and perception was highlighted. The use of a multidisciplinary approach provided more useful and accurate sensory profile representing an ecological, valid food consumption context that will ultimately offer new strategies for successfully developing healthier food products with lower fat and sugar content or elaborated with plant protein, for which sensory acceptability remains a challenge.