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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

<b>REACTIVE EXTRUSION OF BEAN FLOURS</b>

Anael K Kimble (17684091) 20 December 2023 (has links)
<p dir="ltr">Bean flour possesses a significant fraction of water-insoluble components that are known to limit its uses in food applications. This study aimed to determine if using specific enzymes targeting the dietary fiber of bean flour could increase solubility, release protein and starch, and improve its utilization as a replacement for soy protein isolates in meat analogues. Water solubility, protein solubility, starch content and texture of bean flour was measured after enzymatic treatment with pectin- or hemicellulose-degrading enzymes in aqueous suspension. Low moisture reactive extrusion trials ranged from 60-80% solid content at 2 % enzyme content. High moisture extrusion ranged from 30% solid content from 1.5 to 5% enzyme content and from 40 % solid content at 2% enzyme content. Water solubility and insoluble protein increased with both low and high moisture reactive extrusion. Starch content increased with high moisture reactive extrusion. Beta-glucanase increased starch and insoluble protein content more than polygalacturonase treatments. However, Polygalacturonase and beta-glucanase increased overall water-solubility similarly. Determined starch content decreased with low moisture extrusion and both enzymes behaved equally. In the final set of trials, meat analogues were prepared with wheat gluten in combination with soy protein isolate, bean flour, or a mixture of soy protein isolate and bean flour. Replacing soy protein isolate with bean flour in meat analogues provided comparable hardness and anisotropic index. Polygalacturonase and beta-glucanase treatments during reactive extrusion of bean flours both decreased hardness of bean-containing meat analogues; beta-glucanase decreased the anisotropic index, whereas analogues made from polygalacturonase-treated flour did not differ from the control. Therefore, reactive extrusion showed either negative or null impact on texture. Reactive extrusion with polygalacturonase and beta-glucanase improved some desired analytical targets for bean flours, but the practical application (meat analogue) did not demonstrate an improvement.</p>
132

Epigallocatechin-3-Gallate Reduces Fat Accumulation in Caenorhabditis Elegans

Liu, Jinning 11 July 2017 (has links)
Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is a polyphenol that is most abundant in tea. It has been shown from many studies that consumption of EGCG can contribute to weight loss, however, the underlying mechanism is not fully understood. To determine how EGCG acts to reduce fat, an organism model Caenorhabditis elegans (C. elegans) is introduced, which is a useful animal system in exploring crucial biological mechanisms that are readily applicable to humans. In this study, different strains were raised for two days on a diet with or without 100µM and 200µM EGCG treatment: N2 (i.e., wild type) and mutants (i.e., knockdown of fat metabolism related genes). EGCG’s effect on fat reduction was characterized by triglyceride content, food consumption and physiological behaviors. Our results showed that 100 and 200 µM EGCG significantly reduced the triglyceride content of wild type worms by 10% and 20%, respectively, without affecting its food intake and physiological behaviors. Additionally, EGCG could effectively reduce fat accumulation in C. elegans dependent on acs-2 and atgl-1.
133

The application of food-grade chitosan and another food-grade compound in coatings to control Tyrophagus putrescentiae (Schrank, Family: Acaridae) growth on dry-cured hams and their impact on dry-cured ham quality

Shao, Wenjie 11 May 2022 (has links)
The objective of this research was to evaluate if chitosan and another food-grade compound can be incorporated into food-grade coatings in conjunction with propylene glycol and polysaccharides to control Tyrophagus putrescentiae growth without affecting sensory attributes, water activity, and moisture content of dry-cured hams. Each coating solution was coated on ham cubes (2.5 × 2.5 × 2.5 cm3, n = 5/treatment) or infused in ham nets, and dry-cured ham cubes were wrapped in the ham nets prior to inoculation with 20 mixed-sex adult mites. Randomized complete block designs with two replications were utilized to evaluate the efficacy of treatments at controlling mite growth on dry-cured ham cubes. When CH was mixed with XG and infused into a net, fewer mites (15.7 and 21.0 mites) were on ham cubes (P < 0.05) in comparison to the control (211.2 mites). Results indicated that CH contributed to controlling mite growth since 1% XG alone did not control mite growth. Difference from control test results indicated that no sensory differences existed (NS) between CH-treated and control ham slices. The addition of a food-grade compound (SP or 24P) to the XG coatings enhanced mite control efficacy. When 1% SP was added to 1% XG, it effectively controlled mite growth in both coating and netting treatments. Increasing 1% SP to 2% SP did not significantly (NS) control mite growth in the coating solution but did control mite growth when infused in the net. Both coating and netting treatments with 2% 24P + 1% XG controlled mite growth. When 24P was the only ingredient in the treatment, both 1% and 2% 24P controlled mites when infused in the net. The addition of SP did not (NS) impact the sensory attributes of the dry-cured ham. The 2% 24P + 1% XG treatment differed in moistness (P < 0.05) when compared to the blind control, but the rating was still less than 2 (moderately different). Overall, results from these studies indicate that chitosan can potentially be added in coatings or ham nets as tools to control mites in an integrated pest management program for dry-cured hams.
134

Growing tea in Mississippi

Zhang, Qianwen 13 May 2022 (has links) (PDF)
Tea is the most popular beverage worldwide, second only to water. The United States is the third largest importer of tea in the world, importing a total of about 260 million pounds tea annually. With increased demand for locally sourced food products, questions are raised regarding whether domestic production of tea is feasible. Compared to major tea producing countries with centuries of growing history, tea production in the U.S. is limited and requires research support in many aspects of tea production. The objectives of this study were to investigate plant growth, leaf morphology, and seasonal chemical compositions in tea leaves of nine tea cultivars grown in Mississippi, United States; evaluate the effects of black, blue and red shade nets on plant growth and seasonal leaf quality of tea plants; and investigate the content of mineral nutrients in tea leaves of different cultivars and one cultivar under different colors of shade nets. The nine tested tea cultivars varied in plant growth, leaf morphology, cold tolerance, biochemical composition [including soluble solids, carbohydrates, total polyphenols (TP), free amino acids (AA), L-theanine, and caffeine], and mineral content in tea leaves. Among all cultivars transplanted to the field from one-gallon containers in spring 2017, ‘BL2’ had the greatest plant growth index (PGI) when measured in Feb. 2018 and Feb. 2019, which may be helpful toward suppressing weeds and early establishment of a tea plantation. ‘Christine’s Choice’ had the highest content of nitrogen, phosphorus, sulfur, zinc, iron, and boron, and the second highest content of potassium, calcium, and magnesium. The cultivars evaluated in this study generally adapted well to the local environment. All tea samples collected from the nine cultivars and three seasons were considered suitable for green tea processing with low total polyphenol to free amino acids ratios (TP/AA) ranging from 1.72 to 3.71. When compared to unshaded control, black, blue, and red shade nets increased PGI, net photosynthetic rate, and stomatal conductance, decreased N content in tea leaves, decreased air and leaf surface temperatures in summer and reduced cold damage in winter. Red shade nets were considered helpful for improving green tea quality by increasing the content of L-theanine and free amino acids in tea leaves collected in spring and fall compared to unshaded control.
135

Investigating Phenolic-Mediated Protein Matrix Development for Potential Control of Cereal Starch Digestion

Leigh C R. Schmidt (6869153) 15 August 2019 (has links)
<div>Shifts in the human diet to more refined foods and ingredients have contributed to the rise in metabolic disease rates associated with long-term consumption of foods causing swift rises in blood glucose response. Foods which result in a more moderate blood glucose curve are considered healthier by increasing satiety and reducing oxidative stress. Sorghum products contain naturally slowly digested starch. The matrix of sorghum porridges contains kafirin protein bodies which cross link around gelatinizing starch molecules, while similar nascent matrices in other cereals aggregate and collapse. The 3-deoxyanthocyanidin pigments unique to sorghum may be accountable for the difference in matrix stability. The density of the starch entrapped in the matrices is thought to partially inhibit α-amylase access to the starch, reducing overall starch digestion and thereby mitigating glucose response. The purpose of this work was to increase our understanding of how phenolic compounds in sorghum interact with endosperm proteins to create a stable matrix, and to explore if the knowledge might be translated to other starchy cereal products. In the first study, phenolic extracts from flours (sorghum, corn masa, white rice) were characterized for phenolic content, antioxidant activity, phenolic components, and their ability to interact with a model protein system (ovalbumin) in order to examine protein polymerization. In the second study, specific phenolic compounds in sorghums (<i>p</i>-coumaric, sinapic, and gallic acids; (+)-catechin; and apigeninidin, a 3-deoxyanthocyanidin found in sorghums) were interacted in the model protein system at different concentrations to observe extent and type of protein polymerization, and promising compounds subjected to fluorescence quenching spectroscopy to examine the nature of the interactions. The final study explored the effects of apigeninidin addition to a yellow corn flour and naturally present anthocyanin (blue corn) on starch digestion and microstructure of porridges by utilizing an <i>in vitro</i> α-amylase assay and confocal microscopy. </div><div>The slow digestion of starch in cooked sorghum products can be attributed to the 3-deoxyanthocyanidin compounds present in the grain participating in sulfhydryl-disulfide interchanges which results in extensive kafirin cross-linking surrounding starch granules. While other phenolic and redox-active components may affect matrix formation and stability, 3-deoxyanthocyanidins appear to have the most direct influence, and their ability to modify food protein matrices appears to have a direct result on starch digestion <i>in vitro</i>.</div>
136

Physical Properties of Food Oils and Factors Affecting Bubble Dynamics During Frying

Shreya Narayan Sahasrabudhe (6533324) 10 June 2019 (has links)
The study is focused on study of surface and interfacial properties of oil at high temperatures, to understand the mechanisms of heat transfer and oil absorption during frying
137

Isolamento, caracterização e quantificação de peptídeos y-glutamil sulfurados no feijão (Phaseolus vulgaris L.) / Isolation, characterization and quantification of -glutamyl sulfide peptides in bean (Phaseolus vulgaris L.)

Giada, Maria de Lourdes Reis 06 October 1995 (has links)
Foi estudada a fração não-protéica de sementes de feijão (Phaseolus vulgaris L. ), tendo por objetivo identificar a presença e conhecer o teor de (&#947;-glutamil peptídeos sulfurados. Estes peptídeos (&#947;-glutamil-S-metilcisteína e (&#947;-glutamil metionina) podem interferir com o doseamento da metionina pelo método da clivagem com brometo de cianogênio e análise do metiltiocianato por cromatografia em fase gasosa. O extrato etanólico contém 21 % do nitrogênio total do feijão. A lavagem do extrato com clorofórmio reduziu o teor de nitrogênio para 5,5%, pela remoção de proteínas co-extraídas. O extrato não-proteico assim obtido foi purificado sucessivamente por resinas de troca catiônica e aniônica, ocorrendo a separação dos constituintes pelos seus valores de pK. A purificação foi acompanhada por testes químicos, cromatografia em camada delgada e análise de aminoácidos. Foi identificada com base nas suas características químicas, a presença de S-metilcisteína, principalmente na forma de dipeptídeo com ácido glutâmico. A quantificação do peptídeo após hidrólise ácida (3h / 110° C), resultou num teor de S-metilcisteína total de 0,67g /100g proteína, que corresponde a aproximadamente 50% do teor de metionina no feijão, determinado por cromatografia de troca iônica. Estes resultados podem indicar que o teor de metiltiocianato total, liberado pela metionina e pela S-metilcisteína do feijão (1 ,6%) (determinado em trabalho anterior), descontado do teor de S-metilcisteína (0 ,7%), equivale à metionina quimicamente disponível, correspondendo a aproximadamente 64% da metionina total presente no feijão. No ensaio de germinação das sementes do feijão foi observado um decréscimo da (&#947;-glutamil-Smetilcisteína, indicando uma mobilização dos aminoácidos constitutintes. / The non-protein fraction of Phaseolus vulgrias L. seeds has been analysed to obtain information on the identity and level of (&#947;-glutamyl peptides containing a sulfur amino acid. These peptides (&#947;-glutamyl-S-methylcysteine and (&#947;-glutamyl methionine) could interfere with the determination of methionine measured by cleavage with cyanogen bromide and subsequent gas-chromatographic identification of methylthiocyanate. The ethanolic extract of (&#947;-glutamyl peptides contains 21% of the total seed nitrogen, which decrease to 5,5%, by removing the coextracted bean proteins with chloroform. This non-protein extract was then purified by ion-exchange chromatography on basic and acid resins, taking advantage of the different pK values of the amino acids. The isolation procedure was followed up by chemical analysis, thin layer chromatography and amino acid analysis. Based on their chemical properties we were able to identify the presence of S-methylcysteine, mainly in the form of a dipeptide with glutamic acid. Quantitative analysis of the peptide after acid hydrolysis (3h /110° C) showed a level of 0,67g /total S-methylcysteine /100gbean protein. This content accounted for approximately 50% of the bean methionine content, determined by ion-exchange chromatography. These results might indicate that total methylthiocyanate released from both, methionine and S-methylcysteine of beans, (1,6%) (from a previous paper) subtracted from S-methylcysteine (0,7%) could be recognized as chemically available methionine, corresponding to approximately 64% of total methionine. During seed germination the (&#947;-glutamyl-S-methylcysteine undergo a degradative process resulting in loss of the dipeptide.
138

Advanced Characterization of Glucan Particulates: Small-granule Starch, Retention of Small Molecules, and Local Architecture Defined by Molecular Rotor

Xingyun Peng (5930138) 04 January 2019 (has links)
<p>The discovery and utilization of novel starches with unique superb properties are highly demanded for modern industrial uses. Small-granule starch (SGS) is a category of unconventional starches with the granular size smaller than 10 μm. The potential use of SGS includes many conventional and novel high-value applications, such as texturizing, fat replacement, encapsulation, controlled delivery and nano-engineering. In the present work, we focused on three SGS isolated from amaranth (<i>Amaranth cruentus</i>), cow cockle (<i>Saponaria vaccaria</i>) and sweet corn (<i>sugary-1</i> maize mutant). The basic structural and unique physical properties of SGS were characterized and compared to common large-granule food starches. It was found that (1) the highly branched amylopectin contributed to low crystallinity and pasting viscosities of sweet corn starch, (2) cow cockle starch exhibited high shear-resistance and low retrogradation in prolonged storage, and (3) the amylopectin for amaranth starch was less branched with small clusters, which was associated with the high crystallinity, medium shear-resistance and low pasting viscosity of amaranth starch. Despite the small size of starch granules, SGS in both native and swelling states showed the capacity of retaining small molecules. Compared to large-granule starch, native SGS are more difficult for small molecules to reach an equilibrium permeation. This work provides insights to the fine structure and physicochemical behaviors of selected high-potent SGS, which is believed to support the industrial production and application of SGS in the future.</p> <p>The characteristics of local polymeric structure dominate many critical properties of glucan particles, such as starch retrogradation and the loading and stabilizing of active substance. Molecular rotor (MR), a fluorescent probe, was proposed to fulfill the simple, high-sensitive, and quantitative-based characterization of local glucan architecture (LGA). In the present work, two innovative studies relevant to this novel method were conducted: (1) MR was able to characterize glucans based on its unique fluorescent response to characteristic LGA, (2) MR was able to sensitively probe and visually demonstrate the transition of LGA induced by starch retrogradation. This novel MR-based approach is expected to advance carbohydrate-related researches in the future.</p>
139

Aplicação de um sistema de classificação de carcaças e cortes e efeito pós abate da qualidade de cortes de frango criados no sistema alternativo. / Carcasses and cuts classification system and the effects of time after slaughtering on the quality of meat from chicken raised on natural system.

Alvarado Huallanco, Mónica Beatriz 27 January 2005 (has links)
A qualidade da carne envolve aspectos estéticos, avaliados pelo consumidor e físico-químicos importantes para o processador, os quais podem ser controlados nas diversas etapas de produção. Na primeira fase, a fim de determinar a qualidade de carcaças e cortes aplicou-se um sistema de classificação, os quais foram avaliados na aparência (conformação, conteúdo de carne, cobertura de gordura, depenagem, carne exposta e corte, ossos quebrados, descolorações e hematomas) e classificados em níveis A, B ou C, decrescendo de nível conforme os defeitos se apresentaram, além analisou-se a capacidade de retenção de água (CRA), para esta fase utilizou-se à análise discriminante e análise de variância. Na segunda fase, foram avaliados os atributos de qualidade (cor, pH, CRA, força cisalhamento, perda de peso por cozimento, composição centesimal, análise sensorial) dos cortes de peito, coxa e sobrecoxa às 5, 24, 48 e 72 horas pós abate, para frangos criados no sistema alternativo. Para análise dos resultados foram utilizadas as análises de médias, regressão múltipla, correlação simples de Pearson e correspondência para os atributos físico-químicos e sensoriais. Na classificação foram avaliadas 301 carcaças e 146, 147 e 145 de cortes de peito, coxa e sobrecoxa respectivamente. Das carcaças analisadas, 79,73% apresentaram algum grau de contusão, sendo que 65,78% destas eram de grau leve, dessa forma, foram classificadas como tipo A. Fazendo uso da análise discriminante, 84,9% das carcaças mostraram-se corretas quanto à classificação utilizada, apresentando diferença significativa entre as classes. Os outros defeitos foram arranhões, corte de pele, depenagem, resíduo de pele, fraturas ou ossos quebrados. Quanto aos cortes (peito, coxa e sobrecoxa), a maioria foi classificada na categoria A. Os cortes de peito, coxa e sobrecoxa apresentaram 87,7, 96,2 e 95% das amostras corretamente classificadas, respectivamente. Foi realizada na análise de CRA para peito e coxa, observando-se que o corte da coxa classificada como A apresentou maior valor de CRA comparada com o tipo C. Na avaliação da qualidade dos cortes de peito, coxa e sobrecoxa, verificou-se o comportamento da carne nas características físico-químicas em quatro períodos distintos: 5, 24, 48 e 72 horas após o abate. Com o decorrer do tempo de maturação, no peito observou-se um aumento no valor de L* e um decréscimo da força de cisalhamento da carne de peito, melhorou a qualidade promovendo um amaciamento da carne, entretanto, para a coxa não apresentou mudanças na qualidade com o decorrer do tempo, apenas foi observado um acréscimo no valor a*, porém a sobrecoxa a partir de 48 horas, os efeitos da proteólise do músculo influenciaram um aumento significativo na perda de peso inversamente ao CRA. Quanto à análise sensorial, não houve diferença entre o frango alternativo e convencional e nem entre as horas pós abate para os três cortes. Também foram realizadas as análises de correlação simples de Pearson e correspondência para os atributos físico-químicos e sensoriais. / Meat quality is related to a esthetical aspects, which are evaluated by the consumer, and to physiochemical aspects, which are important to the meat processor. These aspects can be controlled at the various steps during production. In the first phase of this study, aiming at evaluating carcasses and cuts, a grading system was used by which meat appearance (conformation, fleshing, fat covering, feathers, exposed flesh and cuts, broken bones, skin discoloration and bruises) was evaluated. They were grading in A, B and C class, according to defects, besides analyzing a water holding capacity (WHC), in this phase a discriminant and variance analyses were utilized. In the second phase, the attributes quality (colour values, pH, WHC, shear force, cooking loss, chemical composition, sensory analyses) of breast, drumstick and thigh cuts, from chicken raised in natural system, was evaluated 5, 24, 48 and 72 hours after slaughtering. In order to analyze the results, the following were used: analysis of means, multiple regression, Pearson’s simple correlation and the relationship with the physicochemical and sensorial parameters. At grading, a total of 301 carcasses and 146,147 and 145 breasts, drumsticks and thigh broilers, respectively, were evaluated. The results indicated that 79, 73% of the carcasses contained some degree of bruise and that 65, 78% contained light bruise, thus being classified as class A. Results of the discriminant analysis showed that 84,9% of the carcasses was correctly graded, showing significant difference among the classes. Other defects found were scratches, skin cuts, feathers and skin residue, fractured and broken bones. Breast, thigh and drumstick cuts had 87,7, 96,2 and 95,0% of samples correctly graded, respectively. A C analysis was done for breast and drumstick, showing that the drumstick classified as class A had a higher WHC value compared to class C. At the breasts, drumsticks and thigh broilers evaluation, the physiochemical behavior of the meat was studied in four different periods: 5, 24, 48 and 72 hours after slaughtering. During the aging period, an increase in the L+ value and a decrease in the shear force of the breast meat were observed, resulting in a quality improvement by meat softening. The drumstick did not show changes in quality, and only an increase in the value a* was observed. However, the thigh showed a significant increase on the weight loss inversely to the WHC, due to the effects of the muscle proteolysis. The sensorial analysis for the three cuts no significant difference between both the natural and conventional chicken and the time after slaughtering was observed.
140

Effects of Potassium Lactate, Encapsulated Citric Acid and Storage Temperature on Microbial Growth and Shelf Life of Pork Sticks

Su, Yen-Kan 01 May 1992 (has links)
A new product, pork sticks, was developed. Optimum shelf life and safety were major concerns associated with this product. Potassium lactate (3%) or citric acid (0.5%, 0.56%, 0.60% or 0.66%) was added to pork sticks to determine their effects on microbial growth, sensory evaluation, and shelf life when stored frozen (-20°C), refrigerated (2°C), or at room temperature (22°C). Two raw materials, pork blade meat (shoulder meat; 91% lean, 9% fat) and regular 80:20 pork trim (80% lean, 20% fat) were used. The consumer panel preferred lean pork sticks made from blade meat over high-fat pork sticks made from regular 80:20 pork trim, regardless of the addition of potassium lactate (3%) or citric acid (0.5%). Pork sticks vacuum-packaged and held at 2°C or -20°C did not develop bacterial spoilage during six months storage. However, bacterial spoilage and oxidative rancidity occurred in the unpackaged control samples held at 22°C for one month. Incorporation of potassium lactate (3%) or citric acid (0.5%) decreased the color uniformity and red color intensity and increased the brown color intensity of the pork sticks made from blade meat. Vacuum-packaged pork sticks with added citric acid (0.56%, 0.60% and 0.66%) stored at 22°C did not develop bacterial spoilage, but discoloration occurred after one month storage.

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