Thesis (M.Sc.) -- Memorial University of Newfoundland, 1987. / Typescript. Bibliography: leaves 56-64. Also available online.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-06-15T20:56:23Z No. of bitstreams: 2 Dissertacão - Petain Jose Ferreira Neto - 2015.pdf: 1935098 bytes, checksum: 58b97940c1a11dda51ddc983a41e4bd9 (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-06-28T13:06:35Z (GMT) No. of bitstreams: 2 Dissertacão - Petain Jose Ferreira Neto - 2015.pdf: 1935098 bytes, checksum: 58b97940c1a11dda51ddc983a41e4bd9 (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Made available in DSpace on 2016-06-28T13:06:36Z (GMT). No. of bitstreams: 2 Dissertacão - Petain Jose Ferreira Neto - 2015.pdf: 1935098 bytes, checksum: 58b97940c1a11dda51ddc983a41e4bd9 (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) Previous issue date: 2015-07-13 / The Cerrado is the second largest biome in Brazil. Such an environment has a different soil several other regions. There are various living beings in this biome, among them, the actinobacteria. They are microorganisms whose cell wall Gram-positive, >50% G+C (guanine + cytosine) in its DNA, produce substances with high economic value. Actinobacteria are major producers of enzymes useful to humans. L-asparaginase enzyme is used in acute limphoblastic leukemias therapy (ALL) also being used in the pre-treatment of foods rich in reducing sugars, inhibiting the formation of acrylamide. The aim of this study was to produce L-asparaginase enzyme isolated from a soil actinobacteria, characterize the enzyme and identify the species of bacteria isolated. A soil sample from Cerrado was collected and submited to a pretreatment. Chemotaxis of Actinoplanetes spores used for the selection of this organism. Nineteen morphspecies were recovered. We used a medium inducing L-asparaginase, and the pink halo around the colony measured. Isolated BC-A.1 produced the largest halo in less time, with an average enzyme content of 4.1. After the completion of the production steps, partial purification and optimization of enzymatic activity, it was realized that the enzyme produced by isolated morphospecies is very efficient at 40 ° C and pH 8.0. Biochemical, physiological and molecular tests were performed, and the observation with optical microscopy and scanning electron microscopy, but it was not possible to identify the species isolated, probably belongs to the genus Streptomyces. / O Cerrado é o segundo maior bioma do Brasil. Tal ambiente possui um solo diferenciado de várias outras regiões. Existem vários seres vivos neste Bioma, dentre estes, as actinobactérias. São micro-organismos cujas células têm parede celular Gram-positiva, >50% de G+C (guanina + citosina) em seu DNA, produzem diversas substâncias com alto valor agregado. Actinobactérias são importantes produtores de enzimas úteis aos seres humanos. A enzima L-asparaginase é utilizada na terapia de Leucemias Linfoblásticas Agudas (ALL) sendo também empregada no pré-tratamento de alimentos ricos em açúcares redutores, inibindo a formação de acrilamida. O objetivo deste estudo foi produzir a enzima L-asparaginase a partir de uma actinobactéria isolada do solo, caracterizar a enzima e identificar a espécie do isolado bacteriano. Uma amostra do solo foi coletada no Cerrado e passou por um pré-tratamento. Foi utilizada a quimiotaxia dos esporos de Actinoplanetes para a seleção deste organismo. Foram recuperadas 19 morfoespécies. Utilizou-se um meio indutor de L-asparaginase, e o halo róseo ao redor da colônia medido. O isolado BC-A.1 produziu o maior halo em tempo menor, com índice enzimático médio de 4,1. Após a realização das etapas de produção, purificação parcial e otimização da atividade enzimática, percebeu-se que a enzima produzida pela morfoespécie isolada é muito eficiente a 40°C e pH 8,0. Foram realizados testes bioquímicos, fisiológicos e moleculares, bem como a observação em microscopia óptica e microscopia eletrônica de varredura, mas não foi possível identificar a espécie do isolado, provavelmente pertence ao gênero Streptomyces.

INTRODUÇÃO Produtos intermediários da reação de Maillard e da peroxidação, como os compostos dicarbonílicos, reagem facilmente com grupamentos aminas de proteínas e ácidos nucléicos levando a modificações biológicas que podem resultar em patologias observadas no diabetes, aterosclerose e doenças neurodegenerativas. O consumo de Produtos da Reação de Maillard (PRM) aumentou nas últimas décadas e há evidências de que estas substâncias são absorvidas e podem tomar parte em processos patológicos, embora ainda não haja consenso sobre os possíveis efeitos deletério à saúde a partir do aumento de sua ingestão. Ressalta-se a necessidade de estimar o consumo destes PRMs a partir de dados sobre os conteúdos e a ingestão habitual do alimento em questão como cereais matinais e café. Objetivos: a) validar metodologia para quantificar indicadores da reação de Maillard: hidroximetilfurfural (HMF), furosina (FUR), carboximetilisina (CML) e Compostos Intermediários Fluorescentes (CIF) em cereais matinais (flocos e granola) e café; b) avaliar se há diferenças nos teores desses compostos nas diferentes marcas destes produtos comercializados em São Paulo; METODOLOGIA: Foram analisados dois lotes de três marcas de cereais do tipo flocos, três marcas de cereais do tipo granola e cinco marcas de café presentes em 100 por cento dos hipermercados visitados no município de São Paulo. A validação da metodologia para quantificação, empregando HPLC, consistiu no cálculo da exatidão (recuperação), repetibilidade e sensibilidade para os compostos: HMF e FUR. Foram determinados os teores de CIF por espectrofotometria de fluorescência e os teores de CML por teste imunoenzimático. RESULTADOS: Os métodos de determinação de FUR e HMF foram validados conforme o Instituto Nacional de Metrologia, Normalização e 9 Qualidade Industrial (INMETRO). O teor médio de CIF livre e total foram maiores para as amostras de café, com média de 232CIF/mg e 765CIF/mg respectivamente. Não houve diferença (p>0,05) no teor de CIF livre e total entre os flocos F1 e F2. O mesmo foi observado para a granola marcas. G1, G2 e G3 A granola foi o produto com maior teor médio de HMF (67,5mg/Kg) e furosina (301mg/100g de proteína). A FUR não foi detectado nas amostras de café. Todas as marcas dos alimentos estudados para os indicadores HMF e FUR apresentaram diferença estatisticamente significativa (p<0,05). O café apresentou maior teor médio de CML (1823,5ng/mg de proteína), sem diferença entre as marcas (p>0,05) CONCLUSÕES: Os cereais do tipo flocos contribuem para maior ingestão de PRMs da fase inicial da reação de Maillard (RM), a granola contribui para maior ingestão de PRMs da fase intermediária da RM e o café contribui de forma significativa para maior ingestão de PRMs da fase avançada da RM. O café, por ser submetido a tratamento térmico mais severo apresenta maior concentração de PRMs da fase avançada da reação / INTRODUCTION Maillard reaction products and lipid peroxidation, such as dicarbonyl compounds easily react with amino groups of proteins and nucleic acids leading to biological changes that can result in complications in diseases such as diabetes, atherosclerosis and neurodegenerative. The consumption of Maillard Reaction Products (MRP) has increased in recent decades and there is evidence that these substances are absorbed and can participate in pathological processes, although there is no consensus about the possible harmful health effects from their intake. We highlight the need to identify the consumption of MRP, mainly in vulnerable populations like children and diabetics, in order to establish acceptable daily intakes and guidelines for the food industry. OBJECTIVES: a) validate the methodology to measure indicators of the Maillard reaction: hydroxymethylfurfural (HMF), Furosine (RUF) carboxymethylysine (CML) and fluorescent intermediate compounds (FIC) in breakfast cereals (corn flakes and granola) and coffee, b) to evaluate if there are differences in the levels of these compounds contents among brands commercialized in São Paulo METHODS: two lots of 3 brands of flakes cereal, 3 brands of granola and 5 coffee brands present in 100 per cent of supermarkets visited in the city Sao Paulo were analyzed. HPLC methodology validation was assessed by determining accuracy (recovery), repeatability, and sensibility (linearity, limits of detection and quantitation) for the compounds: HMF and FUR. The contents of the Fluorescent Intermediary compounds (FIC) was measured by spectrophotometric method and the levels of CML by ELISA. RESULTS: Calibration curves determination coefficient (r 2) were higher than 0,99 for all compounds. Recovery ranged from 84 to 110 per cent and repeatability average was 3,5 per cent. The average content of free and total FIC was higher for coffee 232CIF/mg and 765CIF/mg respectively. The brands of granola and flakes was similar but just brands F1 and F2 was similar between brands (p<0,05). For HMF the higher values were for granola 67,5mg/kg. The presence of dried fruit in these grains may 11 have contributed significantly to the higher rate of this indicator. For indicator FUR average was higher in granola samples (301mg/100g of protein) and it was not possible to quantify the levels of FUR for coffee. All brands analyzed for HMF and FUR was similar (p<0,05). CML average was higher for coffee (1823,5ng/mg of protein). The brands analyzed was similar for all samples (p <0.05). CONCLUSIONS: Flakes contribute to higher intake of MRPs from early stage of the Maillard reaction (MR), the granola contributes to higher intake of MRPs from intermediate phase of MR and coffee contributes significantly to higher intake of final MRPs. Data suggest that coffee has more severe thermal treatment causing a higher concentration of MRPs from the final phase of the MR

INTRODUÇÃO: A reação de Maillard ocorre em alimentos termicamente processados e também em sistemas biológicos, em que é chamada de glicação. Esta reação ocorre entre grupos carbonilas e grupamentos aminas e tem especial importância em alimentos, pois promovem alterações sensoriais importantes ao sabor, aroma, aparência e textura. Em sistemas biológicos, entretanto, podem acarretar mudanças em estruturas moleculares que favorecem o estresse oxidativo e participam da patogenia de complicações micro e macro vasculares características da diabetes, aterosclerose e doenças neurodegenativas. Os compostos carbonílicos ou produtos da reação de Maillard (PRMs) formados em alimentos contribuem para o aumento do pool endógeno de compostos carbonílicos. A utilização de substâncias ou alimentos que possam minimizar a formação destes compostos pode constituir-se em uma estratégia para minimizar a sua ingestão. OBJETIVO: Avaliar o efeito da adição de extrato etanólico de erva-mate verde na inibição da reação de Maillard em sistemas modelo alimento. METODOLOGIA: Foram elaborados modelos de biscoito e lácteos com e sem lipídios. Os teores de produtos da reação de Maillard [furosina (FUR), hidroximetilfurfural (HMF), carboximetilisina (CML) e produtos fluorescentes (IF)] foram avaliados. O extrato etanólico foi obtido por extração contínua a quente da erva-mate verde seca e caracterizado quanto aos teores de compostos fenólicos, cafeína e saponinas por cromatografia líquida. A intensidade de fluorescência dos sistemas foi avaliada por espectrofotometria, os teores de FUR e HMF foram analisados por cromatografia líquida de alta eficiência e de CML por ELISA. RESULTADOS: O extrato etanólico de erva-mate apresentou 155µg mg -1 de fenólicos totais, 76µg mg -1 de cafeína, 5µg mg de ácido ursólico e 3µg mg -1 de ácido oleanóico. A formação de HMF, FUR e IF nos sistemas modelo de biscoito não foi influenciada pela adição do extrato de erva-mate. O teor de CML do modelo com extrato do sistema de biscoito foi significativamente menor (p<0,05) em que os outros tratamentos com aquecimento, a porcentagem de inibição foi de 8%. A formação dos IF nos sistemas modelos lácteos adicionados de extrato foram significativamente menores (p<0,05) comparado aos modelos lácteos com aquecimento sem adição de extrato, a porcentagem de inibição foi de 30% para o modelo sem lipídeos e de 27% para o modelo com lipídeos. CONCLUSÃO: A adição do extrato etanólico da erva-mate verde foi efetiva em diminuir a reação de Maillard nos modelos de biscoito e lácteos. / INTRODUCTION: the Maillard reaction (MR) occurs in processed foods during heating, processing and storage and in biological systems, where it is called glycation. The MR is initiated by the condensation of amino groups of proteins with the carbonyl group of reducing sugars and has special importance in foods, because they promote sensory changes important to the flavor, aroma, color and texture. In biological systems, this reaction are involved in the progression of several diseases, such as diabetes, cardiovascular complications and neurodegenerative diseases. The Maillard reaction products contribute to increase the endogenous pool of carbonyl compounds. The use of substances or foods that can minimize the formation of these compounds may constitute a strategy to minimize your intake. OBJECTIVES: evaluate the effect of addition of the ethanolic extract of yerba mate in inhibition of the Maillard reaction in model food systems. METHODS: were developed cookies and milk models food systems. The content of Maillard reaction products [Furosine (FUR), hydroxymethylfurfural (HMF), carboxymethyllysine (CML) and fluorescent compounds (IF)] were evaluated. The yerba mate extract was obtained by hot continuous extraction and characterized for the levels of phenolic compounds and saponins by liquid chromatography. The contents of the fluorescent compounds (IF) was measured by spectrophotometric method, HMF and FUR were analyzed by high performance liquid chromatography and the levels of CML by ELISA. RESULTS: The yerba mate extract contained 155g mg -1 of total phenolics, 76g mg -1 of caffeine, 5g mg of ursolic acid and 3g mg -1 of oleanolic acid. The formation of HMF, FUR and IF in cookie systems was not influenced by the addition of the yerba mate extract. The CML content of the cookie model with yerba mate extract was significantly lower (p<0.05) than the other treatments with heating. The IF milk models added extract were significantly lower (p <0.05) than the IF milk models with heating without extract. CONCLUSION: The yerba mate extract reduced the formation of CML in the cookie system and inhibit the Maillard reaction in the intermediate stage in milk systems.

Orientadores: Rosiane Lopes da Cunha, Fernanda Yumi Ushikubo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T02:34:58Z (GMT). No. of bitstreams: 1 Barbosa_JanainaMiranda_M.pdf: 4341938 bytes, checksum: e5e24c14ce9831be45d250772d8a9f57 (MD5) Previous issue date: 2013 / Resumo: As emulsões estão presentes naturalmente em alguns alimentos ou são aplicadas devido a suas propriedades tecnológicas. Porém, as emulsões são termodinamicamente instáveis e tendem a separar de fases com o tempo. A estabilidade das emulsões pode ser melhorada utilizando agentes emulsificantes e estabilizantes. Neste trabalho foi estudada a ação simultânea de dois biopolímeros naturais para melhorar a estabilidade cinética de emulsões óleo - em - água (O/A). Conjugados formados por caseinato de sódio e goma jataí foram produzidos através da reação de Maillard em diferentes razões de proteína/polissacarídeo e tempos de reação, a fim de se obter melhor ação estabilizante que os biopolímeros individuais em emulsões preparadas em duas condições de pH. A formação dos conjugados foi confirmada pela análise de eletroforese em gel de poliacrilamida que evidenciou a presença de compostos de alta massa molecular. De modo geral, em pH 7 as emulsões foram mais estáveis que em pH 3,5, pois em pH neutro a proteína estava mais distante do seu ponto isoelétrico, sendo assim mais solúvel e carregada negativamente, resultando na repulsão eletrostática entre as gotas. As análises de microscopia confocal feitas para emulsões em pH 7 mostraram que com os conjugados formados após 24 h de reação, a distribuição da proteína na interface foi mais homogênea. No pH 3,5, não houve efeito de carga e a estabilidade das emulsões foi atribuída à presença dos polissacarídeos que promoveram maior viscosidade da fase contínua e maior espessura da camada interfacial, provocando repulsão estérica entre as gotas. Neste pH, os conjugados formados após 24 h de reação melhoraram a estabilidade das emulsões. Nas análises reológicas observaram-se maiores valores de viscosidade aparente nas emulsões com o maior conteúdo de polissacarídeo (razão 0,3), e este valor foi ainda maior em pH 7. Dessa forma, os módulos complexos (G*) das emulsões também atingiram valores mais altos em pH neutro, confirmando a melhor estruturação das emulsões. Quanto à reologia interfacial, o módulo complexo de viscoelasticidade (E*) da interface óleo ¿ solução de biopolímero na razão 0,3 apresentou valor elevado e pouca variação ao longo do tempo, caracterizando uma interface mais elástica e estável, com estrutura mais rígida devido ao polissacarídeo. Com estes resultados, pode-se afirmar que os conjugados formados em tempo iniciais de reação e compostos por maior quantidade de goma jataí melhoraram a estabilidade das emulsões devido ao efeito estérico do polissacarídeo que foi ainda mais pronunciado em pH ácido / Abstract: The emulsions are naturally present in some foods or they are applied in food products due to their technological properties. However, emulsions are termodynamically unstable and their phases tend to separate with time. The stability of emulsions can be improved by using emulsifiers and stabilizers. In this work it was studied the combined action of two natural biopolymers to improve the kinetic stability of oil-in-water emulsions (O/W). Conjugates composed by sodium caseinate and locust bean gum were produced by Maillard reaction at different protein/polysaccharide ratio and reaction time to obtain a conjugate with better stabilizing action than individual biopolymers in emulsions prepared at two pH conditions. The conjugates formation was confirmed by polyacrylamide gel electrophoresis analysis that revealed the presence of compounds with high molecular weight after the reaction. In general, the emulsions at pH 7 were more stable than at pH 3.5. At neutral pH, as the protein was further from its isoelectric point, it was more soluble and negatively charged, resulting in the electrostatic repulsion between the droplets. The confocal microscopy analysis showed that emulsions at pH 7 composed by conjugates formed after 24 h of reaction, presented more homogeneous protein distribution at the interface. At pH 3.5, there was no electrical charge effect on the emulsion and the stability was attributed to the presence of polysaccharides, which promoted higher viscosity of the continuous phase and increased the interfacial layer thickness, resulting in steric repulsion between the droplets. Regarding the rheological behavior, it was observed higher values of apparent viscosity in emulsions with highest polysaccharide content (ratio 0.3), and these values were higher at pH 7 than at pH 3.5. Moreover, the complex moduli (G *) values of the emulsions were also higher at neutral pH, confirming better structured emulsions. In relation to the interfacial rheology, the viscoelastic complex moduli (E *) on the oil ¿ biopolymer solution interface at 0.3 ratio presented higher value with low variation with time, characterizing more elastic and stable interface composed by rigid structure due to the polysaccharide. Based on these results, it was observed that the conjugates formed at early reaction time and composed by large amount of locust bean gum improved the emulsions stability due to the steric effect of the polysaccharide which was more pronounced at acid pH / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

Haselnüsse werden als Lebensmittel im Hinblick auf eine ausgewogene und gesunde Ernährung immer beliebter. Sie sind reich an ungesättigten Fettsäuren und Proteinen, enthalten Vitamine, Polyphenole, Antioxidantien und Mineralstoffe sowie weitere bioaktive Substanzen. Regelmäßiger Nusskonsum soll unter anderem koronaren Herzerkrankungen, Gallensteinen und Diabetes (bei Frauen) vorbeugen (Alasalvar und Shahidi, 2009; Ros, 2010). In den Jahren 2006 bis 2014 stieg der Pro-Kopf-Konsum an Nüssen von 3,8 auf 4,6 kg pro Jahr an. Laut der Bundesanstalt für Landwirtschaft und Ernährung (BLE) wurden im Wirtschaftsjahr 2014 (Juli 2014 bis Juni 2015) 345.200 t Nüsse nach Deutschland importiert. Mit 105.000 t wird die Erdnuss in Deutschland am häufigsten verzehrt, doch auch die Haselnuss stellt mit 53.600 t ein sehr beliebtes Nahrungsmittel dar. (BLE, 2015; Ros, 2010) Haselnüsse werden roh oder geröstet, pur oder als Zutat für andere Lebensmittel und Backwaren, verzehrt. Durch die Röstung wird unter anderem die Haltbarkeit durch die Abtötung von Mikroorganismen und der Enzyminaktivierung verlängert (Durmaz und Gökmen, 2010), aber auch Farb- und Aromastoffe gebildet, welche das Aussehen und den Geschmack der Nüsse verbessern. Hierbei spielen vor allem die Maillard-Reaktion, welche eine Vielzahl von Einzelreaktionen von reduzierenden Zuckern mit freien oder proteingebundenen Aminosäureseitenketten, bevorzugt die des Lysins, beschreibt, sowie die Lipierung, welche analog die Reaktion von Protein- bzw. Lysinseitenketten mit Sekundärprodukten der Lipidperoxidation bezeichnet, eine Rolle. Die gewählten Röstbedingungen (Temperatur und Dauer) sind ausschlaggebend für die Bildung von Maillard- und Lipierungsprodukten in Nüssen. Es stellt sich die Frage, in welchem Maße diese Produkte bereits in den rohen Nüssen vorhanden sind und wie sich ihre Gehalte während der Erhitzung in Abhängigkeit von Rösttemperatur und -dauer verändern. Hierfür wurden sechs Maillard-Produkte und drei Lipierungsprodukte ausgewählt und deren Gehalte während der Haselnussröstung verfolgt. Lipierungsprodukte wurden im Rahmen der Arbeit erstmals in Haselnüssen untersucht. Aufgrund des hohen Fettgehalts von Haselnüssen wurden mögliche Einflussfaktoren auf die Bildung von Lipierungsprodukten genauer untersucht und zwischen verschiedenen Nusssorten verglichen. Im Anschluss erfolgte eine Abschätzung der Beeinflussung der Lipierungsproduktbildung in Abhängigkeit der Nusszusammensetzung. Hierbei spielen vor allem Faktoren wie der Fett- und Proteingehalt sowie die Fettsäure- oder Aminosäurezusammensetzung eine Rolle. Ein alternatives Verfahren zur Haltbarmachung, was bereits bei Fleischprodukten und Fruchtsäften Anwendung findet, stellt die Hochdruckbehandlung dar (Henle und Schwarzenbolz, 2015). Bisher wurde dieses Verfahren noch nicht auf Haselnüsse oder Nüsse im Allgemeinen angewandt und es gibt keinerlei Untersuchungen zu strukturellen Veränderungen der Proteine bzw. zu den Auswirkungen auf die Maillard- und Lipierungsproduktbildung im Zuge einer anschließenden Röstung. Aufgrund langer Transportwege und einer möglichweise verbesserten Lagerstabilität roher Nüsse wäre eine Hochdruckbehandlung auch für Haselnüsse relevant. Im Rahmen dieser Arbeit wurden erstmals Untersuchungen zum Einfluss einer Hochdruckbehandlung auf die Bildung von Maillard- und Lipierungsprodukten in Haselnüssen durchgeführt. Die Haselnussallergie stellt, mit etwa 2,2 % Betroffenen in Europa (EFSA, 2014), eine der Hauptnahrungsmittelallergien dar. Schon 10 mg einer rohen Haselnuss können ausreichen, um eine allergische Reaktion hervorzurufen (Worm et al., 2009). Innerhalb Europas lassen sich regionale Unterschiede hinsichtlich des auslösenden Allergens sowie der Schwere der Symptome feststellen. Im Norden Europas stellt das Birkenpollenhomologon Cor a 1 das Hauptallergen dar, welches oft mit einer Kreuzallergie zu anderen birkenpollenassoziierten Lebensmitteln einhergeht und meist eine milde Symptomatik, wie das orale Allergiesyndrom auslöst. Im Südeuropäischen Raum hingegen sind Patienten vor allem gegen das Lipid-Transfer-Protein Cor a 8 sensibilisiert, welches schwere Symptome bis hin zur Anaphylaxie auslösen kann. (Pastorello et al., 2002; Datema et al., 2015) Die Erhitzung und Hochdruckbehandlung von Haselnüssen kann die Allergenität beeinflussen. Im Rahmen dieser beiden Verfahren kann es zu Proteinmodifikationen und zu strukturellen Veränderungen der Proteine kommen, wobei Auf- und Umfaltungsreaktionen Epitope der Allergene maskieren oder freilegen können. Die Allergenität kann somit verringert oder verstärkt werden. In dieser Arbeit wurden die Auswirkungen einer Röstung mit und ohne vorhergehender Hochdruckbehandlung auf das Haselnussallergen Cor a 8 analysiert. Hierbei wurde das allergene Potential anhand des IgE-Bindungsvermögens von Humanseren mittels Western Blots abgeschätzt. Das Ziel dieser Arbeit war es Proteinmodifikationen, die im Rahmen der Röstung und Haltbarmachung von Haselnüssen entstehen, näher zu charakterisieren und deren Einfluss auf das allergene Potential zu beschreiben.

No description available.

No description available.

No description available.

Cocoa beans (Theobroma cacao) are a highly concentrated source of dietary flavanols- bioactive compounds associated with the health protective properties of cocoa. Cocoa beans undergo processing steps, such as fermentation, roasting, winnowing, grinding, pressing, etc., to produce a final product with specific desirable sensory attributes. It is well established that these processing steps, specifically fermentation and roasting, result in dramatic degradation of cocoa's native flavanols, but it is possible that these processing steps may generate compounds with novel activities, potentially preserving or enhancing bioactivity. Raw unfermented cocoa beans were processed by way of a partial factorial approach to produce cocoa powders from the same batch of raw beans using various combinations of fermentation [unfermented, cool fermented (maximum 46°C), hot fermented (maximum 60°C))] and roasting [unroasted, cool roasted (120°C), hot roasted (170°C)]. To simulate cocoa fermentation in a highly controlled environment, a pilot-scale fermentation model system was employed to eliminate many external unknowns and ensure that the differences between our cocoa powders were due to our various treatments, rather than unknown factors occurring during fermentation and roasting. Low and high molecular weight fractions (8-10 kDa cutoff) were produced from cocoa powder extracts (CPE) of each treatment to quantify Maillard reaction products (MRP). A HILIC-UPLC MS/MS method was developed to more efficiently and sensitively quantify cocoa flavanols with high degrees of polymerization (DP) produced during processing. Overall, cocoa processing significantly (p<0.05) decreased the total phenolic and total flavanol concentrations of CPEs. Hot roasting had the greatest impact on native flavanol degradation yet produced CPEs with the highest mean degree of polymerization (mDP). All CPEs dose-dependently inhibited α-glucosidase enzyme activity, with cool fermented/cool roasted cocoa powder exhibiting the best inhibition (IC50 of 62.2 µg/mL). Increasing flavanol mDP was correlated with decreasing IC50 values, suggesting that the complex flavanols produced during processing enhance cocoa's bioactivity (or their production is associated with other products that enhance bioactivity). Alternatively, high molecular weight CPE fractions were correlated with increasing IC50 values, suggesting that MRPs interfere with enzyme inhibition or are associated with other products (polyphenols, macronutrients, etc.) that interfere with enzyme inhibition. Overall, the data presented within this work indicate that the components of processed cocoa powders are promising inhibitors of α-glucosidase, despite a significant reduction in native flavanol composition induced by processing, and moreover that fermentation and roasting conditions can positively influence the bioactivity of cocoa despite losses of native flavanols. / Master of Science in Life Sciences / According to the Centers for Disease Control and Prevention, obesity-related chronic conditions such as cardiovascular disease and type 2 diabetes mellitus (T2D) are the leading cause of preventable and/or premature death, with 51% of the American population predicted to be obese by 2030. Cocoa (Theobroma cacao) is a highly concentrated source of polyphenols, and these compounds have been shown to interact with and inhibit digestive enzymes responsible for carbohydrate breakdown. By inhibiting the activity of these digestive enzymes, it is possible to slow down carbohydrate absorption after a meal and ultimately reduce large spikes in blood glucose levels, being a promising strategy in the prevention and maintenance of T2D. Cocoa beans undergo processing steps to produce a final product, such as cocoa powder, and it is known that these processing steps reduce the levels of beneficial polyphenols. Yet, how this processing-induced degradation effects the health protective activities of cocoa is still widely unknown and is the focus of this work. Through highly controlled cocoa bean processing, cocoa powders of different processing conditions were produced and used to assess how various processing parameters impacted digestive enzyme activity. Overall, processing steps did reduce levels of native polyphenols. However, these losses did not demonstrate a reduction in enzyme inhibition and certain processing conditions actually enhanced digestive enzyme inhibition. This research shows promise for the potential use of processed cocoa powder as an effective strategy in the prevention and maintenance of T2D and further work must be done to understand the mechanisms behind this relationship.