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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.
11

Effect of radiation on polymerization, microstructure, and microbiological properties of whey protein in model system and whey protein based tissue adhesive development

Liu, Ning 01 January 2015 (has links)
Whey proteins are mainly a group of small globular proteins. Their structures can be modified by physical, chemical and other means to improve their functionality. The objectives of this study were to investigate the effect of radiation on protein-protein interaction, microstructure, and microbiological properties of whey protein-water solutions. Whey protein isolate (WPI) solutions (27-36% protein) were treated with different dosages (10-35 KGy) of gamma radiation. The protein solutions were analyzed for viscosity, turbidity, soluble nitrogen, total plate count, and yeast and mold counts. The interactions between whey proteins were also analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and scanning electron microscopy (SEM). The viscosity of protein solution (27%, w/w) was increased from 2.19 for the control to 4.78 mPa*s for the sample treated at 25 KGy, respectively, and viscosity also increased during storage at 23°C. The soluble nitrogen (10%, w/w) was decreased from 100% to 54.7% for control and the sample treated at 35 KGy. The effects of gamma radiation and storage time on viscosity of whey protein solutions were significant (p
12

Efeito da ingestão de proteína de amaranto no metabolismo do colesterol em ratos / Effect of amaranth protein isolate intake on cholesterol metabolism in rats

Vaz, Lilian Carolina Martins de Assis 29 October 2010 (has links)
Introdução As doenças cardiovasculares estão entre as principais causas de morte no Brasil e no mundo. Evidências epidemiológicas e clínicas estabelecem associação entre dieta, dislipidemia e aumento do risco de morte. O consumo de proteína isolada de amaranto tem efeito hipocolesterolemizante e por isso pode reduzir, de modo significativo, os fatores de risco das doenças cardiovasculares. Objetivo Avaliar o efeito da ingestão do isolado protéico de amaranto, no perfil de lipoproteínas plasmáticas e na expressão de proteínas relacionadas à modulação da síntese do colesterol hepático. Métodos Vinte e oito ratos Wistar (Ratus novergicus) foram distribuidos em quatro grupos e receberam dietas diferenciadas pela fonte protéica. Os grupos experimentais (I e Icol) receberam dieta com 20por cento de proteína de amaranto e os grupos controle (C e Ccol) receberam dieta com 20por cento de caseína. As dietas col apresentavam 1por cento de colesterol. Ao grupo controle foi fornecida a média da quantidade de ração ingerida pelos grupos experimentais I e Icol (controle pair feeding). Para determinar o efeito da ingestão das dietas no metabolismo do colesterol, foram avaliadas as concentrações plasmáticas de triacilgliceróis, colesterol total e HDL-c, e as concentrações hepáticas de colesterol e lipídios totais. O efeito da ingestão da proteína de amaranto na regulação das vias de síntese do colesterol hepático foi investigado pela avaliação da expressão das proteínas nucleares: receptor X hepático alfa (LXR alfa), receptor ativado por proliferadores de peroxissoma alfa (PPAR alfa) e proteína ligadora do elemento regulado por esterol 2 (SREBP-2). Resultados A dieta Icol promoveu menor concentração plasmática de colesterol total e triacilgliceróis (36por cento e 47por cento , respectivamente) em comparação ao grupo Ccol. Observou-se, no fígado dos animais alimentados com dieta contendo proteína isolada de amaranto (I e Icol), menor concentração de lipídios totais e de fração colesterol. A digestibilidade entre as dietas Icol e Ccol não apresentou diferença significativa, enquanto a da dieta I foi menor que a da dieta C. Não foi observada alteração na expressão das proteínas PPAR alfa e LXR alfa em nenhum dos grupos. Uma redução significativa na expressão da proteína SREBP-2 foi verificada no fígado dos ratos que receberam dieta Icol em relação aos do grupo Ccol. Conclusão A ingestão de dieta Icol reduz de forma significativa a expressão do SREBP-2 no fígado de ratos. Essa redução sugere que o efeito hipocolesterolemizante promovido pela proteína de amaranto pode estar relacionado ao metabolismo endógeno do colesterol. Esse efeito independe da ação dos fatores de transcrição PPAR alfa e LXR alfa e pode estar associado à formação de peptídeos bioativos, muito embora os mecanismos não estejam claros. O isolado protéico apresenta efeito hepatoprotetor por diminuir o acúmulo de lipídios hepáticos mesmo quando o colesterol está presente na dieta / Introduction - Cardiovascular diseases are among the most important causes of death in Brazil and around the world. Epidemiologic and clinical evidences associate diet, dyslipidemia, and increased risk of death. Consumption of amaranth protein isolate has a hypocholesterolemic effect that may reduce, significantly, cardiovascular disease risk factors. Objective To assess the effect of amaranth protein isolate intake on plasma lipoprotein profile and on expression of proteins that modulate hepatic cholesterol synthesis. Methods Twenty eight Wistar rats were distributed in four groups and fed on different protein diets. The experimental groups (I e Icol) diets contained 20per cent amaranth protein and the control groups (C e Ccol) diets contained 20per cent casein. The col diets also contained 1per cent cholesterol. It was offered to the control group the mean of the amount of food consumed by the experimental groups (pair feeding control). In order to determine the effects of dietary intake on cholesterol metabolism, plasma total cholesterol, triglycerides, and HDL-c levels were assessed, as well as hepatic total lipids and cholesterol levels. The effect of amaranth protein on pathways of cholesterol synthesis was investigated by liver X receptors alpha (LXR alpha), peroxisome proliferator activated receptors alpha (PPAR alpha) and sterol regulatory element binding protein 2 (SREBP-2) expressions. Results Rats fed on Icol diet showed lower concentrations of plasma total cholesterol and triglycerides (36per cent and 47per cent, respectively) than those observed in Ccol diet group. A lower cholesterol and hepatic lipid concentration was observed in rats fed on amaranth protein isolate (I e Icol). There was no significant difference shown between the digestibility of the Icol and Ccol diets, although the digestibility of the I diet was lower than the digestibility of the C diet. No change was noticed in PPAR alpha and LXR alpha expression in any of the studied groups. There was a significantly down-regulation in SREBP-2 expression in the liver of rats fed on Icol diet when compared to those fed on Ccol diet. Conclusions The consumption of Icol diet reduces significantly SREBP-2 expression in the liver of rats. This decrease in SREBP-2 expression suggests that the hypocholesterolemic effect of the amaranth protein may be related to the endogenous metabolism of cholesterol. This effect does not depend on the transcription factors PPAR alpha and LXR alpha, and may be associated with bioactive peptides formation, although the mechanisms involved are not yet clear. The protein isolate has a hepatic-protective effect because it lowers hepatic lipid accumulation even when cholesterol was present in the diet
13

Efeito do consumo de tremoço (Lupinus albus) e seu isolado protéico no metabolismo do colesterol em hamsters hipercolesterolemizados

Fontanari, Gustavo Guadagnucci [UNESP] 18 June 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-06-18Bitstream added on 2014-06-13T19:01:13Z : No. of bitstreams: 1 fontanari_gg_dr_arafcf.pdf: 3134034 bytes, checksum: cedb3c38cb79d12942589999bc81fb5a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A soja e outras leguminosas são consideradas alimentos funcionais por apresentarem propriedades hipocolesterolemizantes. Esta propriedade, porém, ainda não foi elucidada para o tremoço e seus isolados protéicos. Um possível componente deste grão responsável pelo efeito redutor de colesterol é sua proteína. Objetivo: Produzir isolado protéico de tremoço e verificar a influência do grão integral e de seus isolados protéicos no metabolismo do colesterol de hamsters hipercolesterolemizados pela dieta. Métodos: O isolado protéico (IP) de tremoço foi produzido por precipitação isoelétrica, utilizando-se pH 10,0 para solubilização da proteína e pH 5,0 para sua precipitação, obtendo-se um isolado protéico de 92,41% de proteína. O IP e a farinha de tremoço integral (FI) foram usados como fonte protéica em dietas experimentais para hamsters que tiveram hipercolesterolemia induzida por dieta contendo 13,5% de gordura saturada e 0,1% de colesterol, por 21 dias. Os animais foram divididos em 3 grupos, recebendo cada grupo dieta com 20% de caseína (controle), dieta com 20% de proteína respectiva do IP e dieta com 20% de proteína respectiva da farinha integral de tremoço (FI), por 28 dias. Resultados: Comparando-se a dieta controle (HC), as dietas IP e FI provocaram reduções significativas no colesterol total (15,3 e 16,88%, respectivamente) e colesterol não-HDL (28,6 e 43,41%, respectivamente). Análises histológicas do fígado foram realizadas e observou-se que o IP e o FI apresentaram efeito hepatoprotetor comparado à HC, que apresentou esteatose difusa e intensa (nível 4+), enquanto que os grupos tremoço integral e isolado protéico apresentaram esteatose focal (nível 1). Alguns possíveis mecanismos envolvidos para o efeito benéfico no metabolismo lipídico foram investigados. A excreção... / Soya and other legume seeds are considered functional food because of their hypocholesterolemic properties. However this property was still not elucidated for lupine and its protein isolates. A possible component of this grain responsible for the redactor effect of cholesterol is its protein. Objective: Produce lupine isolate and verify the influence of the whole grain and its protein isolate on cholesterol metabolism in diet hipercholesterolemized. Methods: The lupin protein isolate (PI) was produced by isoelectric precipitation, using pH 10.0 for solubilization of the protein and pH 5.0 to its precipitation, obtaining a protein isolate of 92.41% of protein. The PI and lupine flour whole (FW) were used as source of protein in experimental diets for hamsters that had hipercholesterolemia induced by a 21 days diet containing 13.5% of saturated fat and 0.1% of cholesterol. The animals were divided into 3 groups, receiving each group a 28 days diet with 20% of casein (Control), diet with 20% of protein of protein isolate of lupine (PI) and diet with 20% of protein from lupine whole flour (WF). Results: Comparing the control diet (HC), the diets PI and WF caused significant reductions in total cholesterol (15.3 and 16.88%, respectively) and cholesterol not-HDL (28.6 and 43.41%, respectively). Histological analysis of liver were accomplished and noticed that the PI and the WF presented hepatoprotector effect compared to HC, which presented diffuse and intense steatosis (level 4+), while the groups whole lupine and protein isolate, presented focal steatosis (level 1). Some possible mechanisms for the beneficial effects in lipid metabolism were investigated. The excretion of fecal cholesterol was inversely proportional to the plasmatic levels of the animals cholesterol submitted to the different diets. The animals with the WF diet... (Complete abstract click electronic access below)
14

Movement superposition and space multiple build: alternative thinking of Bacon's Triptych from the viewpoint of Deleuze¡¦ Francis Bacon: the logic of sensation

Liu, Chun-yun 28 January 2011 (has links)
none
15

Efeito da ingestão de proteína de amaranto no metabolismo do colesterol em ratos / Effect of amaranth protein isolate intake on cholesterol metabolism in rats

Lilian Carolina Martins de Assis Vaz 29 October 2010 (has links)
Introdução As doenças cardiovasculares estão entre as principais causas de morte no Brasil e no mundo. Evidências epidemiológicas e clínicas estabelecem associação entre dieta, dislipidemia e aumento do risco de morte. O consumo de proteína isolada de amaranto tem efeito hipocolesterolemizante e por isso pode reduzir, de modo significativo, os fatores de risco das doenças cardiovasculares. Objetivo Avaliar o efeito da ingestão do isolado protéico de amaranto, no perfil de lipoproteínas plasmáticas e na expressão de proteínas relacionadas à modulação da síntese do colesterol hepático. Métodos Vinte e oito ratos Wistar (Ratus novergicus) foram distribuidos em quatro grupos e receberam dietas diferenciadas pela fonte protéica. Os grupos experimentais (I e Icol) receberam dieta com 20por cento de proteína de amaranto e os grupos controle (C e Ccol) receberam dieta com 20por cento de caseína. As dietas col apresentavam 1por cento de colesterol. Ao grupo controle foi fornecida a média da quantidade de ração ingerida pelos grupos experimentais I e Icol (controle pair feeding). Para determinar o efeito da ingestão das dietas no metabolismo do colesterol, foram avaliadas as concentrações plasmáticas de triacilgliceróis, colesterol total e HDL-c, e as concentrações hepáticas de colesterol e lipídios totais. O efeito da ingestão da proteína de amaranto na regulação das vias de síntese do colesterol hepático foi investigado pela avaliação da expressão das proteínas nucleares: receptor X hepático alfa (LXR alfa), receptor ativado por proliferadores de peroxissoma alfa (PPAR alfa) e proteína ligadora do elemento regulado por esterol 2 (SREBP-2). Resultados A dieta Icol promoveu menor concentração plasmática de colesterol total e triacilgliceróis (36por cento e 47por cento , respectivamente) em comparação ao grupo Ccol. Observou-se, no fígado dos animais alimentados com dieta contendo proteína isolada de amaranto (I e Icol), menor concentração de lipídios totais e de fração colesterol. A digestibilidade entre as dietas Icol e Ccol não apresentou diferença significativa, enquanto a da dieta I foi menor que a da dieta C. Não foi observada alteração na expressão das proteínas PPAR alfa e LXR alfa em nenhum dos grupos. Uma redução significativa na expressão da proteína SREBP-2 foi verificada no fígado dos ratos que receberam dieta Icol em relação aos do grupo Ccol. Conclusão A ingestão de dieta Icol reduz de forma significativa a expressão do SREBP-2 no fígado de ratos. Essa redução sugere que o efeito hipocolesterolemizante promovido pela proteína de amaranto pode estar relacionado ao metabolismo endógeno do colesterol. Esse efeito independe da ação dos fatores de transcrição PPAR alfa e LXR alfa e pode estar associado à formação de peptídeos bioativos, muito embora os mecanismos não estejam claros. O isolado protéico apresenta efeito hepatoprotetor por diminuir o acúmulo de lipídios hepáticos mesmo quando o colesterol está presente na dieta / Introduction - Cardiovascular diseases are among the most important causes of death in Brazil and around the world. Epidemiologic and clinical evidences associate diet, dyslipidemia, and increased risk of death. Consumption of amaranth protein isolate has a hypocholesterolemic effect that may reduce, significantly, cardiovascular disease risk factors. Objective To assess the effect of amaranth protein isolate intake on plasma lipoprotein profile and on expression of proteins that modulate hepatic cholesterol synthesis. Methods Twenty eight Wistar rats were distributed in four groups and fed on different protein diets. The experimental groups (I e Icol) diets contained 20per cent amaranth protein and the control groups (C e Ccol) diets contained 20per cent casein. The col diets also contained 1per cent cholesterol. It was offered to the control group the mean of the amount of food consumed by the experimental groups (pair feeding control). In order to determine the effects of dietary intake on cholesterol metabolism, plasma total cholesterol, triglycerides, and HDL-c levels were assessed, as well as hepatic total lipids and cholesterol levels. The effect of amaranth protein on pathways of cholesterol synthesis was investigated by liver X receptors alpha (LXR alpha), peroxisome proliferator activated receptors alpha (PPAR alpha) and sterol regulatory element binding protein 2 (SREBP-2) expressions. Results Rats fed on Icol diet showed lower concentrations of plasma total cholesterol and triglycerides (36per cent and 47per cent, respectively) than those observed in Ccol diet group. A lower cholesterol and hepatic lipid concentration was observed in rats fed on amaranth protein isolate (I e Icol). There was no significant difference shown between the digestibility of the Icol and Ccol diets, although the digestibility of the I diet was lower than the digestibility of the C diet. No change was noticed in PPAR alpha and LXR alpha expression in any of the studied groups. There was a significantly down-regulation in SREBP-2 expression in the liver of rats fed on Icol diet when compared to those fed on Ccol diet. Conclusions The consumption of Icol diet reduces significantly SREBP-2 expression in the liver of rats. This decrease in SREBP-2 expression suggests that the hypocholesterolemic effect of the amaranth protein may be related to the endogenous metabolism of cholesterol. This effect does not depend on the transcription factors PPAR alpha and LXR alpha, and may be associated with bioactive peptides formation, although the mechanisms involved are not yet clear. The protein isolate has a hepatic-protective effect because it lowers hepatic lipid accumulation even when cholesterol was present in the diet
16

PHONETIC VARIATION IN KAMËNTS̈Á: AN ANALYSIS OF STOPS AND AFFRICATES

Benavides Pantoja, Jose Nicolas 01 September 2021 (has links)
AN ABSTRACT ON THE THESIS OFJose Benavides Pantoja, for the Master of Arts degree in Linguistics presented on April 30, 2020, at Southern Illinois University Carbondale. TITLE: PHONETIC VARIATION IN KAMËNTS̈Á: AN ANALYSIS OF STOPS AND AFFRICATESMAJOR PROFESSOR: Dr. Karen Baertsch This study contributes to the limited body of research concerned with documenting and studying the minority and indigenous languages of the world. More specifically, it focuses on Kamënts̈á, a language isolate spoken by less than 500 people in southern Colombia. According to UNESCO (2003), this language has been categorized as “definitely endangered” which makes its documentation even more critical. Although there have been initial investigations undertaken by Juajibioy, Howard, and McDowell, the scarce accessible research has relied on purely impressionistic reviews of the language, leading to unreliable conclusions and descriptions of the language. This thesis constitutes the first phonetic acoustic analysis of Kamënts̈á language in order to substantiate what has been described in the current literature. Additionally, the geographic location where Kamënts̈á emerged, together with Spanish, and Inga Kichwa has proven to be an intriguing sociohistorical and linguistic landscape for the study of these languages being an area worth of investigating. Given that there is no existing documentation of language variation in the language, the primary goal of this thesis is to analyze the production of plosive and affricate segments at a word-level to examine language variation at a phonetic level. Considering that Kamënts̈á has been poorly documented, it was not surprising for differences in the production to be found. One difference fell in the phonemic status of the segment between younger and older speakers of the language. The production of the segments in three linguistic environments at word-level attested for variation of some phonemes. For this study, data were collected from two experimental tasks. For the first task, eight Kamënts̈á-Spanish bilinguals (N=8) were recorded producing words in isolation in a word-elicitation exercise. The purpose of this task was to gather raw data on the production of the segments at word level. For the second task, the consultants were asked to take a sociolinguistic questionnaire. This instrument was designed to account for the linguistic ethnography and language ecology of the Kamënts̈á. The purpose of this task was also to tie sociolinguistic data from the speakers with any phonemic differences in the realization of the segments. Results supported the VOT framework proposed by Lisker and Abramson (1964) as an effective metric to measure the voicing status of plosives. For the analysis of affricates, the center of gravity and spectral peak location demonstrated accurate acoustic correlates to capture frication in the phonemes. Equally, amplitude provided valuable information for the analysis of prenasalization. What is more, consistent resemblances were found comparing Kamënts̈á with other studies regarding the acoustic cues, place and manner of articulation, and voicing status of the phonemes.
17

Effect of Whey Protein Isolate on Oxidative Stress, Exercise Performance, and Immunity

Shute, Max 17 March 2004 (has links)
The purpose of this study was to evaluate the effectiveness of a whey protein isolate (WPI), a reported glutathione (GSH) booster, on exercise performance, immune function, and antioxidant status during weight maintenance and energy restriction in humans. Twenty well-trained, college age, male cyclists performed a cycling exercise test for 45 min, the first 7 min at 70% of VO2peak and the remaining 38 min at 55% VO₂peak immediately followed by a performance test set at 90% VO2peak until exhaustion. Blood samples were collected prior to the exercise test, after 45 min of exercise, within 5 min of exhaustion, and 1 h after exercise. Blood samples were analyzed for GSH, GSH/GSSG ratio, glutathione peroxidase (GPx), lipid hydroperoxides (LPO), phagocytosis, oxidative burst, peripheral blood mononuclear cell (PBMC) proliferation, and PBMC phenotyping. Subjects consumed 40g/day of WPI or casein placebo (P) along with their normal diet for 2 wk, repeated the exercise test, and then began a low energy period continuing the same supplementation for 4 d before the final exercise test. WPI was not associated with superior exercise performance or antioxidant status following exercise or weight loss. WPI supplementation did result in 33% greater lymphocyte proliferation capacity following exercise. Following exhaustive exercise for all trials, tGSH and GPx increased 7% and 11%, respectively, while WBCGSH decreased 13%. For WPI, GPx activity was 10% lower than P following exhaustive exercise for all trials combined. Weight loss (2.67 ± 0.26 kg) resulted in increases in phagocytosis (65%), white blood cell (WBC) GSH (40%), and GPx (35%) while decreasing the GSH/GSSG ratio (55%) and LPO (16%). Exhaustive exercise caused a 28% increase in CD8+ PBMCs and decreased CD4+ (34%), CD3+ (15%), the CD4+/8+ ratio (45%), and phagocytosis (8%) with all values returning to baseline after 1 h recovery. Supplementation with WPI did not enhance GSH status or exercise performance in trained cyclists, during weight maintenance or energy restriction. Following exercise, WPI is associated with greater lymphocyte proliferation of PBMCs which may help maintain an athlete's health during heavy training or competition. / Ph. D.
18

Associative phase separation in admixtures of pea protein isolates with gum Arabic and a canola protein isolate with i-carrageenan and alginate

Klassen, Darlene Renae 28 June 2010
The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p> In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p> In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.
19

Associative phase separation in admixtures of pea protein isolates with gum Arabic and a canola protein isolate with i-carrageenan and alginate

Klassen, Darlene Renae 28 June 2010 (has links)
The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p> In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p> In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.
20

IMPACT OF HOMOGENIZATION AND UHT PROCESSING ON THE EMULSIFICATION AND PHYSICAL PROPERTIES OF PEA PROTEIN BEVERAGES

Xiang Cheng (17583861) 10 December 2023 (has links)
<p dir="ltr">Pea protein is one of the most used plant proteins in food products, acting as an alternative to conventional animal protein sources due to its abundant, nutritious, and ease in supply chain characteristics. The objective of this study was to investigate the impact of homogenization and UHT processing parameters on the properties of protein emulsion. Protein emulsions (8% w/w pea protein isolate and 1% w/w sunflower oil) were freshly prepared prior to processing, and the untreated sample was considered as the control (NT). The pilot-scale aseptic processing system (APS) used in this study consisted of two coil-in-shell heaters and two coolers. Samples flowed through each section of the APS system following this order: balance tank, pre-heater, final heater, hold tube, pre-cooler, and final cooler. The homogenizer was located either after the pre-cooler (AC) or the pre-heater (AH) with a controlled temperature of 165F. A third setup was utilized by bypassing the homogenizer in the UHT system. An additional 8-hour continuous run was conducted to mimic a commercial manufacturing operation by recirculating the protein emulsion in the UHT system, and fouling detections were made using a non-intrusive sensor (NICS). 5% w/w soy protein, 1% w/w sunflower oil oil-in-water emulsion was also used for fouling tests. Protein concentration, pH and zeta potential, Cryo-SEM microscopic image, particle size distribution, flocculation index (FI), coalescence index (CI), viscosity and color data were collected and analyzed. The protein concentration had a 23.20 ± 4.00 %, 28.35 ± 5.02 %, 27.98 ± 5.05% and 21.38 ± 5.75% reduction for AC, AH, UHT and NT samples, respectively, when compared with the initial concentration in the formula. AC, AH, UHT and NT samples had pH values of 7.24 ± 0.01, 7.27 ± 0.01, 7.28 ± 0.02, 7.41 ± 0.01, and zeta potential values of -42.91 ± 0.89, -47.30 ± 0.91, -46.91 ± 1.40 and -50.11 ± 1.47 mV. AC sample had a smaller and NT sample had a bigger, respectively, mean weighted size D 4,3 value than AH and UHT samples, which could also be seen in Cryo-SEM images where only AC images contained more visually observable smaller particles. FI and CI for AC, AH and UHT indicated the formation of flocs but no irreversible aggregations were found. Shear-thinning AC, AH, UHT and NT samples had viscosity decreases from 4.00 to 3.56, 3.88 to 3.75, 4.02 to 3.79 and 10.42 to 9.56 mPa*s in 1 1/s to 100 1/s shear rate range. NT sample had a very noticeable color difference from the other three treated samples. Overall, AC samples had similar or better emulsion stability in all aspects than AH and UHT samples, suggesting that AC processing could potentially be used in the protein beverage industry for manufacturing products with improved shelf stability. Severe foulants buildups were neither observed nor detected by a non-intrusive continuous sensor (NICS) in the UHT system within 8 hours of process for both pea protein and soy protein emulsion, indicating that this UHT-homogenization processing can potentially be adapted to current industrial practices for higher-quality protein beverages.</p>

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