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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

Caracterização e estabilidade de micropartículas de antocianinas extraídas do bagaço da produção do suco de jabuticaba

Souza, Ana Cardinale Pereira January 2014 (has links)
A busca de fontes alternativas de pigmentos naturais tem estimulado o desenvolvimento de pesquisas com diferentes frutos e resíduos tropicais. No presente trabalho, optou-se por estudar o aproveitamento do bagaço gerado na produção de suco de jabuticaba. A jabuticaba é uma fruta rica em antocianinas, um pigmento natural que, além da capacidade de conferir cor, também possui atividades benéficas à saúde. No entanto, o seu uso como corante natural na indústria de alimentos como uma forma de substituir os corantes sintéticos é limitado pela sua instabilidade frente às condições de processamento e da presença de outros componentes. Uma alternativa para aumentar a estabilidade das antocianinas é através da técnica de microencapsulação no qual o ingrediente sensível é protegido dentro do material de revestimento. Assim, o presente estudo objetivou a produção, caracterização e a verificação da estabilidade dos pós obtidos por liofilização utilizando a maltodextrina, a pectina e a proteína isolada de soja como materiais de parede em diferentes proporções. Os pós foram caracterizados quanto ao teor de umidade, atividade de água, solubilidade, higroscopicidade, tamanho de partícula, morfologia, análise térmica e colorimétrica, teor de fenólicos totais, antocianinas monoméricas e atividade antioxidante com o radical ABTS. Os mesmos também foram avaliados quanto à estabilidade na presença da luz UV durante a estocagem e comparadas com o extrato de antocianinas liofilizado não microencapsulado. As antocianinas presentes no bagaço de jabuticaba foram extraídas com ultrassom utilizando a água acidificada com ácido cítrico (1 %) O extrato de antocianinas concentrado apresentou uma quantidade de antocianinas monoméricas de 510 ± 0,09 mg.100 g-1 de bagaço, um teor de fenólicos totais de 12.860 ± 1,5 mg AGE.100 g-1 bagaço e uma atividade antioxidante de 39.590 ± 1,25 μM TE.g-1 de bagaço todos expressos em base seca. Os pós produzidos por liofilização apresentaram estruturas irregulares amorfas sem estrutura cristalina com tamanho médio de partículas entre 311,66 – 419,74 μm com distribuição bimodal. Além disso, as amostras apresentaram baixos valores de umidade (2,09 ± 0,10 a 4,15 ± 0,32%), atividade de água (0,053 ± 0,003 a 0,162 ± 0,002), higroscopicidade (10,8 ± 0,1 a 14,2 ± 0,3 g/100g) e baixa solubilidade em água (10,9 ± 0,1 a 21,3 ± 0,2 %), atributos desejáveis na obtenção de alimentos em pó. Com a análise térmica foi possível verificar que houve a microencapsulação das antocianinas com os diferentes materiais de revestimento testados devido à formação de novas transições endotérmicas, e ainda foi possível observar que os pós apresentaram uma estabilidade térmica até a temperatura de 130 °C. A fotoestabilidade dos pós liofilizados bem como do extrato de antocianinas liofilizado não microencapsulado armazenados por 90 dias mostraram que a degradação desse pigmento seguiu uma cinética de primeira ordem e os parâmetros cinéticos foram calculados Para o extrato não microencapsulado os valores obtidos para a constante de degradação e tempo de meia-vida foram iguais a 0,0135 d-1 e 51 dias, respectivamente, correspondendo a uma redução de 77% de antocianinas monoméricas, 56 % de fenólicos totais e 43 % da capacidade antioxidante. Por outro lado, os materiais de parede protegeram o pigmento do efeito deletério da luz em mais de 90 % em relação ao teor de fenólicos totais, 80 % para a quantidade de antocianinas monoméricas, de modo que a atividade antioxidante foi mantida em 70 % durante o período de estocagem. Os valores da constante de degradação para todas as formulações variaram de 0,0022 a 0,0070 d-1 e os tempos de meia-vida variaram de 101 a 320 dias. Portanto, os resultados obtidos neste estudo demonstraram que a pectina e a proteína isolada de soja podem ser consideradas potenciais materiais de revestimento na microencapsulação de antocianinas a serem utilizados na indústria de alimentos. / The search for alternative sources of natural pigments has stimulated the development of research with different tropical fruits and their waste; in the present work, we chose to study the use of the bagasse generated in the production of jaboticaba juice was studied. Jaboticaba is a fruit rich in anthocyanins, a natural pigment, which besides the ability of providing color, also has beneficial health activities. However, its use as a natural colorant in the food industry, replacing the synthetic coloring agents is limited by their instability due to the process conditions and the presence of other components. An alternative to increase stability of anthocyanins is microencapsulation technique in which the sensitive ingredient is protected within the coating material. The present work aims the production, characterization and verification of the stability of the powders obtained by freeze-drying using maltodextrin, pectin and the isolate soy protein as wall materials in different proportions. The powders were analyzed for moisture content, water activity, solubility, hygroscopicity, particle size, morphology, thermal and colorimetric analysis, total phenolics content, total monomeric anthocyanin and capacity to scavenge the ABTS.+. They were also evaluated for stability in the presence of UV light during storage and compared with the lyophilized extract of anthocyanins not microencapsulated. Anthocyanins were extracted from jaboticaba pomace with ultrasound using water acidified with citric acid (1%) The concentrated extract anthocyanins showed an amount of monomeric anthocyanins of 510 ± 0.09 mg. 100g-1 a content of total phenolics of 12.860 ± 1.5 mg GAE.100g-1 and antioxidant activity of 39,590 ± 1.25 μM TE.g-1 pomace dry basis. In addition, the samples presented low moisture values (2.09 ± 0.10 to 4.15 ± 0.32%), low water activity (0.053 ± 0.003 to 0.162 ± 0.002) and hygroscopicity ranging from 10.8 ± 0.1 to 14.2 ± 0.3 g/100g as well as low solubility in water (10.86 ± 0.1 to 21.28 ± 0.2%) which are desirable attributes for food powder. Through the thermal analysis it was verified that the anthocyanins were effectively microencapsulated with the different coating materials tested due to the formation of new endothermic transitions; it was also observed that the powders showed a thermal stability up to 130 °C. The photostability the powders and extract of anthocyanins lyophilized not microencapsulated stored for 90 days showed that this pigment degradation followed a first-order kinetics. For the extract not microencapsulated the values obtained of degradation and half-life were equal to 0.0135 d-1 and 51 days, respectively, corresponding to a 77 % reduction of monomeric anthocyanins, 56% total phenolics content and 43 % of antioxidant capacity In contrast, the wall material protected the pigment against the deleterious effect of light in more than 90 % for total phenolic content and 80 % for the amount of monomeric anthocyanins, so the antioxidant activity remained at 70 % for the storage period. The rate constants according to a first-order reaction for all formulations ranged from 0.0022 to 0.0070 d-1 and the half-life times ranged from 101 to 320 days. Therefore, the results of this study showed that the pectin and the isolate soy protein can be potentially be used as coating materials in the microencapsulation of anthocyanins for use in the food industry.
12

Atividade acaricida, inibi??o da acetilcolinesterase e an?lise qu?mica de res?duos agroindustriais

Bispo, Jorge Luiz Peixoto 27 April 2018 (has links)
Submitted by Verena Pereira (verenagoncalves@uefs.br) on 2018-07-12T21:46:04Z No. of bitstreams: 1 JORGE LUIZ PEIXOTO BISPO.pdf: 1928389 bytes, checksum: 3d95674032c8b830a0db8b942fc740ae (MD5) / Made available in DSpace on 2018-07-12T21:46:04Z (GMT). No. of bitstreams: 1 JORGE LUIZ PEIXOTO BISPO.pdf: 1928389 bytes, checksum: 3d95674032c8b830a0db8b942fc740ae (MD5) Previous issue date: 2018-04-27 / The aim of this study was to analyze the in vitro efficacy of crude extracts of agroindustrial residues obtained from fruits against engorged females of Rhipicephalus microplus, using the adult immersion test. The first chapter gathers studies about the fruits used in this study and the bovine ectoparasites of economic importance. In the second chapter, the fruit residues of Spondias mombin, Tamarindus indica, Genipa americana and Citrus latifolia were submitted to maceration with ethanol to obtain the extracts. Engorged females were collected for acaricidal evaluation. The treatments consisted of six groups with extracts at 50 mg mL-1 concentration and two control groups (positive: fipronil and negative: 70 % ethanol). The extract of S. mombin fruit peel showed an acaricidal efficiency of 96.37 %. In order to investigate the mechanism of acaricide action, the in vitro effect of the extracts against acetylcholinesterase was evaluated and only the extract of the bagasse of C. latifolia showed a correlation with the acaricide effect. The extracts were monitored by high performance liquid chromatography and identified derivatives of phenolic compounds. In the third chapter, the fruit extract of S. mombin presented an acaricidal efficacy of 98.4 % at a concentration of 12.5 mg mL-1 and larvicidal efficacy of 84.8 % at a concentration of 25 mg mL-1. After fractionation of the S. mombin extract, the fraction with the major inhibition potential of the acetylcholinesterase enzyme was identified. The active fraction was analyzed by gas chromatography and a mixture of unsaturated fatty acids and terpenoids were identified, which act synergistically in the acaricidal action / O presente trabalho teve como objetivo analisar a efic?cia in vitro dos extratos bruto de res?duos agroindustriais contra f?meas ingurgitadas de Rhipicephalus microplus, utilizando o teste de imers?o de adultos. O primeiro cap?tulo re?ne estudos sobre os frutos utilizados neste trabalho e os ectoparasitos bovinos de import?ncia econ?mica. No segundo cap?tulo, os res?duos dos frutos de Spondias mombin, Tamarindus indica, Genipa americana e Citrus latifolia foram submetidos a macera??o com etanol para obten??o dos extratos. F?meas ingurgitadas foram coletadas para avalia??o acaricida. Os tratamentos foram constitu?dos por seis grupos com extratos na concentra??o 50 mg mL-1 e dois grupos controles (positivo: fipronil; e negativo: etanol 70 %). O extrato da casca do fruto de S. mombin apresentou efic?cia de 96,37 %. Com o intuito de investigar o mecanismo de a??o acaricida, foi avaliado o efeito in vitro dos extratos frente a acetilcolinesterase e apenas o extrato do baga?o de C. latifolia apresentou correla??o com o efeito acaricida. Os extratos foram monitorados por cromatografia l?quida de alta efici?ncia e identificado derivados de compostos fen?licos. No terceiro cap?tulo o extrato da casca do fruto de S. mombin apresentou uma efic?cia acaricida de 98,4 % a uma concentra??o de 12,5 mg mL-1 e efic?cia larvicida de 84,8 % a uma concentra??o 25 mg mL-1. Ap?s o fracionamento do extrato de S. mombin, foi identificada a fra??o com maior potencial de inibi??o da enzima acetilcolinesterase. A fra??o ativa foi analisada por cromatografia gasosa e identificou-se mistura de ?cidos graxos insaturados e terpen?ides, que agem sinergicamente na a??o acaricida
13

Potencial da Farinha de Bagaço de Maçã no tratamento dietoterápico de pessoas idosas Ponta Grossa 2007

Coelho, Laylla Marques 23 August 2007 (has links)
Made available in DSpace on 2017-07-21T18:53:07Z (GMT). No. of bitstreams: 1 LAYLLAMARQUES.pdf: 1145086 bytes, checksum: c1ab51b02d49ea74dbcec3569b8c3d6c (MD5) Previous issue date: 2007-08-23 / The industrialization of the apple, in particular of the juice, generates in the processing, as main residue, or by-product, the pomace, for which the concern in managing it adequately must be enters the priorities of the processing industries. The composition physicist-chemistry of the apple pomace flour in this study presented 43% of staple fibers in dry base. The studies on staple fibers demonstrate that they show a hypocholesterolemic action, therefore reduce the digestion and the absorption of the dietary lipids, increases the fecal eliminate acid biliary and steroid the neutral ones, increases the production of acid of short chain in colon and diminishes the percentage of biliary elementary schools in bile. The objective of this study was to develop an alimentary product for an assay of cost evaluation/benefit, with group of aged in confinement, being used 30 g/day apple pomace flour, supplemented in products daily. The research counted on the free participation of 31 citizens that had carried through laboratories examinations of glucose, cholesterol and fractions and triglycerides and had answered questions on intestinal functioning. The averages of the results of total cholesterol and LDLcholesterol shown that in the group it was controlled did not have reduction during the intervention with the apple pomace flour and in the group in intervention of the apple pomace flour in its feeding had reduction of up to 14,71% and 14,69% respectively. Proving that the apple pomace flour can constitute potential alternative source of the alimentary fiber for the food formularization and demonstrates to trend in the reduction of the total cholesterol and LDL-cholesterol. / A industrialização da maçã, em particular do suco, gera como principal resíduo, ou subproduto, o bagaço, sendo que a preocupação em gerenciá-lo adequadamente deve estar entre as prioridades das indústrias processadoras. A composição físico-química da farinha de bagaço de maçã neste estudo apresentou 43% de fibras em base seca. Os estudos sobre as fibras demonstram que elas exercem uma ação hipocolesterolêmica, pois reduzem a digestão e a absorção dos lipídeos dietéticos, aumentam a excreção fecal dos ácidos biliares e esteróis neutros, aumentam a produção de ácidos graxos de cadeia curta no cólon e diminuem a porcentagem de ácidos biliares primários na bile. O objetivo deste estudo foi desenvolver um produto alimentar, num ensaio de avaliação de custo/benefício, com grupo de idosos em confinamento, utilizando 30g de farinha de bagaço de maçã/dia, suplementados em produtos do cotidiano. A pesquisa contou com a livre participação de 31 idosos, que realizaram exames laboratoriais de glicemia, colesterol e frações e triglicerídeos e responderam questões sobre seu funcionamento intestinal. As médias dos resultados de colesterol total e LDLcolesterol mostraram que no grupo controle não houve redução durante a intervenção com a farinha de bagaço de maçã e no grupo em intervenção da farinha de bagaço de maçã em sua alimentação houve redução de até 14,71% e 14,69% respectivamente, comprovando que a farinha de bagaço de maçã pode constituir fonte alternativa potencial da fibra alimentar para a formulação de alimentos e demonstra tendência na redução do colesterol total e LDL-colesterol.
14

Extraktion av polyfenoler från pressrester av röda vindruvor / Extraction of polyphenols from red grape pomace

Haidarian, Behroz, Lidborg, Christina January 2011 (has links)
Antioxidanter är kemiska ämnen som är kapabla till att förhindra oxidation av andra molekyler. Dessa ämnen återfinns i djur- och växtriket och tycks ha en skyddande effekt på cellvävnad genom att motverka skadliga oxidativa reaktioner. Antioxidanter används bland annat industriellt som tillsater i livsmedel och andra produkter i syfte att förhindra oxidativ degradering och bibehålla näringsvärdet i livsmedel. I vindruvor återfinns höga koncentrationer av naturliga antioxidanter, främst i form av fenoliska ämnen. På grund av att vinindustrin bidrar till stora mänger avfall, främst i form av druvrester, är det önskevärt att hitta en effektiv metod för att återvinna fenoliska antioxidanter från avfallet.I detta arbete användes lösningsmedel-extraktion för att extrahera fenoliska ämnen från pressrester av röda vindruvor av varianten Tempranillo. Syftet var att uvärdera effekterna av extraktionsmetod, typ av lösningsmedel, extraktionstemperatur samt extraktionstid på fenol-innehåll och antioxidant aktivitet i extrakten. Två typer av extraktionsmetoder jämfördes; Soxhlet-extraktor och direkt-kontakt-extraktion (DCE), samt tre olika lösningsmedel; en blandning av etanol och vatten (1:1), ren etanol samt etyl acetat. Koncentrationen av fenoliskt innehåll i extrakten erhölls med hjälp av Folin-Ciocalteu's metod, och antioxidant aktivetet med FRAP (Ferric reducing ability of plasma) metoden.Utifrån erhållna data kunde det ses att extraktion med en blandning av etanol och vatten (1:1) som lösningsmedel gav högst fenolisk koncentration och antioxidant aktivitet för alla testade parametrar, medans etyl acetat gav de lägsta värdena. Soxhlet-extraktorn visade sig vara den bästa metoden då den gav högre värden i extrakten jämfört med DCE metoden. För DCE metoden kunde det ses att en extraktionstid på 2½ timmar vid 55 grader var mest optimalt då etanolbaserade lösningsmedel användes. / Program: Högskoleingenjörsutbildning i kemiteknik
15

Interactions of wheat macromolecules and fibres from fruit processing by-products using model systems and the application example muffin / Wechselwirkungen zwischen Weizenmakromolekülen und Fasern aus Nebenprodukten der Fruchtsaftproduktion in Modell-Systemen und dem Anwendungsbeispiel Muffin

Struck, Susanne 01 June 2018 (has links) (PDF)
By-products of fruit, cereal and vegetable processing are often regarded as waste while they contain significant amounts of dietary fibre and phytochemicals that can positively contribute to the human diet when reused as food ingredient. The application of fibre from by-products in baked goods could increase the sustainability of the processing chain but is usually associated with changes in product characteristics, such as lower volume, denser structure and increased hardness. In the current study, the interactions of fibres from by-products and wheat macromolecules were analysed in muffins, starch slurries and wheat doughs. The three selected fibres differed significantly in their chemical composition and technofunctional properties. In muffins wheat flour replacement by apple fibre was assessed by rheological measurements of batter and determination of product characteristics. Water proportion adaption based on batter viscosity to create isoviscosity was evaluated as a promising method to develop muffins with satisfying characteristics, where a wheat flour replacement of 30 % is suggested. The addition of apple fibre influenced starch gelatinisation in muffins during baking as indicated by the results of pasting experiments and in vitro starch digestion. Starch slurries with apple and wheat fibre were analysed in pasting experiments. Soluble dietary fibre, mainly pectin, strongly influenced the pasting profile of wheat starch, in comparison to insoluble dietary fibre, that acted as an inert filler and did not interact with the starch. Wheat doughs with fibre from by-products were analysed for rheology, texture and microstructure. The gluten development was negatively influenced by the fibres, which resulted in less extensible doughs. Soluble dietary fibre resulted in increased dough stickiness and limited dough handling at high application levels. It can be reasoned that dough with 10% fibre from by-products would produce products with satisfying characteristics, whereas higher application levels cannot be recommended without using additives to increase the gluten strength. Fibres from by-products are suitable wheat flour replacers in bakery products, where the negative effects of the high water binding capacity of the fibre, can be partly balanced by water proportion adaption, especially in products were gluten development is not that dominating for product structure, like in muffins or cakes. / Nebenprodukte der Obst-, Getreide- und Gemüseverarbeitung werden oft als Abfall betrachtet, wobei sie signifikante Gehalte an Ballaststoffen und sekundären Pflanzeninhaltsstoffen aufweisen, und bei der Verwendung als Lebensmittelzutat positiv zur menschlichen Ernährung beitragen können. Die Anwendung von Fasern aus Nebenprodukten in Backwaren könnte die Nachhaltigkeit der Verarbeitungskette erhöhen, ist jedoch mit Änderungen der Produkteigenschaften verbunden, wie verringertes Volumen, dichtere Struktur und erhöhte Härte. In der vorliegenden Studie wurden die Wechselwirkungen von Fasern und Weizenmakromolekülen in Muffins, Stärkesuspensionen und Weizenteigen analysiert, wobei sich die drei ausgewählten Fasern in ihrer chemischen Zusammensetzung und ihren technofunktionellen Eigenschaften unterschieden. In Muffins wurde die Mehlsubstitution durch Apfelfaser anhand von Teigrheologie und Produkteigenschaften analysiert. Die Anpassung des Wassergehaltes basierend auf der Teigviskosität wurde als vielversprechende Methode zur Entwicklung von Muffins mit akzeptablen Eigenschaften bewertet, wodurch ein Mehlersatz von 30% möglich war. Die Zugabe von Apfelfasern beeinflusste die Stärkeverkleisterung in Muffins, wie durch die Ergebnisse von Verkleisterungsexperimenten und In vitro-Stärkeverdauung gezeigt wurde. Stärkesuspensionen mit Apfel- und Weizenfasern wurden auf ihr Verkleisterungsverhalten analysiert. Lösliche Ballaststoffe beeinflussten das Verkleisterungsprofil von Weizenstärke im Vergleich zu unlöslichen Ballaststoffen, die als inerter Füllstoff fungierten und nicht mit der Stärke in Wechselwirkung traten. Weizenteige mit Fasern wurden auf Rheologie, Textur und Mikrostruktur untersucht. Die Glutenentwicklung wurde durch die Fasern negativ beeinflusst, was zu weniger dehnbaren Teigen führte. Lösliche Ballaststoffe führten zu einer erhöhten Teigklebrigkeit. Weizenteig mit 10% Faser besitzt zufriedenstellenden Eigenschaften, während höhere Fasermengen nicht zu empfehlen sind, ohne Zusatzstoffe, um die Glutenfestigkeit zu erhöhen. Fasern aus Nebenprodukten sind geeignet als Mehlersatz in Backwaren, wobei die negativen Auswirkungen der hohen Wasserbindekapazität der Faser teilweise durch Wasseranpassung ausgeglichen werden können, insbesondere in Produkten, bei denen die Glutenentwicklung nicht die Produktstruktur dominiert, wie in Muffins oder Kuchen.
16

Beta-frutofuranosidase de aspergillus versicolor utilizando fonte de carbono alternativa: produção, purificação e caracterização enzimática / Beta-frutoranosidade de aspergillus versicolor using alternative carbon source: production, purification and enzymatic characterization

Dapper, Taiomara Butzke 27 February 2015 (has links)
Made available in DSpace on 2017-07-10T14:38:25Z (GMT). No. of bitstreams: 1 taiomara.pdf: 1065464 bytes, checksum: af0fbef1e995478eaa14a58b94c0cbd0 (MD5) Previous issue date: 2015-02-27 / Extracellular β-fructofuranosidase production from Aspergillus versicolor was significantly increased after optimization of culture conditions by Central Composite Rotational Design (CCRD). The variables studied were apple pomace, initial pH and cultivation time, and in response to enzymatic activity of β-fructofuranosidase. The maximum yield of β-fructofuranosidase was obtained when the fungus was grown for 12 days in medium supplemented with 3% (w/v) apple pomace as carbon source and the initial medium pH 7.0. In the purification procedure, the extracellular crude extract of A. versicolor was precipitated with ammonium sulfate 75%, and applied to the ion exchange chromatography DEAE-Sephadex, which resulted in two peaks of enzyme activities, named β-fructofuranosidase-I and II. The β-frutofuranosidase- I exhibited optimum temperature and pH of 55°C and 6.0, respectively. The enzyme was stable at temperatures from 40 to 60°C and the pH in a range from 3.0 to 6.0. The activity of β-fructofuranosidase-I was increased in the presence of the Fe2+ ion, and inhibited by Hg2+. The kinetic parameters Vmax and Km with sucrose as substrate were 26.71 mm and 56.980 μmol.min-1, respectively. These biochemical characteristics of the β-fructofuranosidase demonstrate the potential application of this enzyme in the ethanol production industry, which requires high temperature stability and acidic pH. / A produção de β-frutofuranosidase extracelular de Aspergillus versicolor foi significativamente elevada após otimização das condições de cultivo através do Delineamento Composto Central Rotacional (DCCR). As variáveis estudadas foram: bagaço de maçã, pH inicial do meio mineral e tempo de cultivo, tendo como resposta a atividade enzimática da β-frutofuranosidase. A produção máxima de β-frutofuranosidase foi obtida quando o fungo foi cultivado por 12 dias, em meio suplementado com 3% (p/v) de bagaço de maçã como fonte de carbono e pH inicial 7,0 do meio mineral. No procedimento de purificação, o extrato bruto extracelular do A. versicolor foi precipitado com sulfato de amônio 75%, em seguida submetido à cromatografia de troca iônica DEAE-Sephadex, que resultou em dois picos de atividade enzimática, denominadas de β-frutofuranosidase I e II. A β-frutofuranosidase I exibiu temperatura e pH ótimos de 55ºC e 6,0, respectivamente. A enzima mostrou estabilidade nas temperaturas de 40 a 60ºC e foi estável em pH na faixa de 3,0 a 6,0. A atividade da β-frutofuranosidase I foi aumentada na presença do íon Fe2+, mas inibida pelo íon Hg2+. Os parâmetros cinéticos Km e Vmáx utilizando sacarose como substrato, foram 26,71 mM, e 56,980 μmol.min-1, respectivamente. Estas características bioquímicas da β-frutofuranosidase evidenciam o potencial de aplicação desta enzima na indústria de produção de etanol, que exige estabilidade a temperatura alta e pH ácido.
17

Extrato de bagaço de uva como antioxidante natural em carne de frango processada e armazenada sob congelamento / Grape pomace extract as natural antioxidant in processed chicken meat stored under freezing

Selani, Miriam Mabel 19 May 2010 (has links)
A carne de frango, em razão da elevada concentração de ácidos graxos insaturados, é altamente suscetível ao processo de oxidação lipídica, que afeta sabor, aroma, cor e textura dos alimentos, limitando sua estabilidade e vida-útil. Devido à possível toxicidade dos antioxidantes sintéticos e à demanda atual por produtos mais saudáveis, o uso de antioxidantes naturais, como o extrato de semente e casca de uva, representa uma alternativa na prevenção da oxidação lipídica em carne de frango, além de permitir aproveitamento do resíduo do processamento do vinho e suco de uva. Assim, o objetivo deste trabalho foi avaliar extratos de bagaço de uva (sementes e cascas) das variedades Isabel e Niágara (Vitis labrusca L.) quanto à atividade antioxidante em carne de frango processada crua e cozida. Foram adicionados à carne de frango 4 tipos de antioxidantes: butilhidroxitolueno; mistura comercial de eritorbato de sódio, ácido cítrico e açúcar; extrato de semente e casca de uva Isabel; extrato de semente e casca de uva Niágara; além do tratamento controle, sem antioxidante. A carne de frango foi processada no formato de mini-hambúrgueres, embalada a vácuo e armazenada sob congelamento (-18°C), durante 9 meses. As amostras foram caracterizadas através da determinação da composição centesimal. A cada três meses, foram realizadas análises de pH, cor instrumental, avaliação microbiológica, oxidação lipídica (valor das substâncias reativas ao ácido tiobarbitúrico TBARS) e análise sensorial. Não foi verificada alteração significativa (p>0,05) na composição centesimal e no valor de pH de amostras cruas e cozidas, em nenhum dos tratamentos analisados. Ambos os extratos de bagaço de uva mostraram efeito na inibição da oxidação lipídica da carne de frango crua e cozida, apresentando resultados comparáveis aos antioxidantes sintéticos utilizados. Houve interferência dos extratos de bagaço de uva na coloração da carne de frango cozida. Na análise de cor objetiva, os tratamentos com extrato de semente e casca de uvas Isabel e Niágara apresentaram-se mais escuros, menos avermelhados e com menor intensidade de cor amarela e, na análise subjetiva, as notas destes tratamentos, para o atributo alteração de cor, foram significativamente maiores (p<0,05) que as dos demais tratamentos. A coloração da carne de frango crua não foi afetada pela adição dos extratos. Através da análise sensorial, o extrato de bagaço de uva Isabel causou menor alteração no sabor e odor da carne de frango, apresentando resultados semelhantes aos antioxidantes sintéticos. Os resultados da análise microbiológica indicaram que as amostras de todos os tratamentos apresentaram-se dentro dos padrões estabelecidos pela legislação brasileira. A utilização de bagaço da indústria vinícola (semente e casca) como antioxidante natural, combinado com o uso da embalagem a vácuo e armazenamento congelado, pode ser considerada um método eficiente para retardar a oxidação lipídica de carne de frango processada, tanto crua, como cozida. Entretanto mais estudos devem ser conduzidos a fim de aprimorar a compatibilidade dos extratos ao produto, buscando minimizar suas interferências nas características sensoriais e organolépticas. / Chicken meat, due to the high concentration of unsaturated fatty acids, is highly susceptible to lipid oxidation, which affects taste, aroma, colour and texture of foods, limiting its stability and shelf-life. Due to the possible toxicity of synthetic antioxidants and the current demand for healthier products, the use of natural antioxidants, such as grape seed and peel extract, is an alternative in the prevention of lipid oxidation in chicken meat, and allows the use of residues from wine and grape juice processing. Thus, the objective of this study was to evaluate grape pomace extracts (seeds and peels) of Isabel and Niagara varieties (Vitis labrusca L.) on the antioxidant activity in raw and cooked processed chicken meat. Four types of antioxidants were added to chicken meat: butylhydroxytoluene; commercial mixture of sodium erythorbate, citric acid and sugar; Isabel grape seed and peel extract; Niagara grape seed and peel extract; and the control, without antioxidant. The chicken meat was processed in the form of mini-burgers, vacuum packaged and stored under freezing (-18°C) for 9 months. The samples were characterized by determining the proximate composition. Every three months, the following analyses were carried out: pH, instrumental color, microbiological evaluation, lipid oxidation (value of thiobarbituric acid reactive substances - TBARS) and sensory analysis. No significant changes (p>0.05) in proximate composition and pH values were observed for raw and cooked samples, in none of the treatments. Both grape pomace extracts showed effect on inhibiting lipid oxidation in raw and cooked chicken meat, with results comparable to synthetic antioxidants used. There was interference from grape pomace extracts in the color of cooked chicken meat. In the objective color analysis, Isabel and Niagara grape seed and peel extract treatments were darker, less red and with less intense yellow color, and in the subjective analysis, the scores for these treatments, for attribute color alteration, were significantly higher (p<0.05) than the other treatments. The color of raw chicken meat was not affected by the addition of extracts. Through sensory evaluation, the Isabel grape pomace extract caused less change in taste and odour of chicken meat, with results similar to synthetic antioxidants. The results of microbiological analysis indicated that samples from all treatments were within the standards established by Brazilian legislation. The use of pomace from the wine industry (seeds and peels) as natural antioxidant, combined with the use of vacuum packaging and frozen storage, can be considered an effective method to retard lipid oxidation in processed chicken meat, both raw and cooked. However, further studies should be conducted in order to improve the compatibility of the extracts to the product, aiming to minimize its interference in the sensorial and organoleptic characteristics.
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Microencapsulation Of Phenolic Compounds Extracted From Sour Cherry (prunus Cerasus L.) Pomace

Cilek, Betul 01 September 2012 (has links) (PDF)
The main objective of the study was to encapsulate the phenolic compounds from sour cherry pulp in micro size, to investigate the physicochemical properties of capsules and their digestability in simulated gastric and intestinal fluid. The effect of different coating materials, ultrasonication time and core to coating ratio on encapsulation of phenolic compounds from sour cherry pomace was investigated. Maltodextrin and gum Arabic were chosen as coating materials. Coating material was prepared with different maltodextrin:gum Arabic (MD:GA) ratios of 10:0, 8:2, 6:4 to make the total solid content 10%. In addition, two different core to coating ratios of 1:10 and 1:20 were used. Emulsions were prepared by homogenization through ultrasonication at 160 W power and 20 KHz frequency for different time periods (5-30 min). Then, the emulsions were freeze dried for 48 hours to obtain the microcapsules. Encapsulation efficiency, antioxidant activity, surface morphology, particle size, color, digestability and glass transition temperatures of the microcapsules were determined. The microcapsules with a core to coating ratio of 1:20 were found to have higher encapsulation efficiencies (78.80-92.26%) than those with a core to coating ratio of 1:10 (69.38-77.83%). Increasing the gum Arabic ratio in the coating material increased encapsulation efficiency. Optimum conditions for encapsulation with the highest efficiency and the lowest particle size were sonication time of 22.5 min, MD:GA ratio of 8:2 and core to coating ratio of 1:20. Encapsulation was effective in preventing the release of the phenolic compounds in gastric fluid. On the other hand, phenolic compounds were released from the capsules into the intestinal fluid.
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Effect Of Nanoencapsulation Of Purified Polyphenolic Powder On Encapsulation Efficiency, Storage And Baking Stability

Luca, Alexandru 01 July 2012 (has links) (PDF)
The primary objective of this study was to obtain nano-emulsion containing polyphenolic compounds extracted from sour cherry pomace and to investigate the effect of degritting of polyphenolic concentrates on the encapsulation efficiency and particle size distribution of capsules and emulsions. It was also aimed to study storage and baking stability of the capsules. Extracted polyphenolic concentrate was degritted at 10,000 rpm for 2 min. Purification reduced Sauter mean diameter (D[32]) of concentrated extract from 5.76 &mu / m to 0.41 &mu / m. Unpurified and purified concentrates were freeze dried for 48 h to obtain extracted phenolic powder (EPP) and purified extracted phenolic powder (PEPP), respectively. Powders were entrapped in two types of coating materials which contain 10% maltodextrin (MD) or 8% MD-2% gum arabic (GA). Samples were prepared by ultrasonication (160 W, 50% pulse) for 20 min. Emulsions containing EPP had D[32] of 1.65 and 1.61 &mu / m when they were entrapped in 10% MD and 8% MD-2% GA coating material solutions, respectively. It was possible to obtain nano-emulsions when purification step was performed. Emulsions prepared with PEPP and coated with 10% MD and 8% MD-2% GA had D[32] of 0.396 and 0.334 &mu / m, respectively. Encapsulation efficiency of the capsules increased significantly from 86.07-88.45% to 98.01-98.29% by means of degritting (p&le / 0.001). Loss of total phenolic content during storage at 43% and 85% relative humidities was smaller for encapsulated powders when compared to powders not entrapped in coating material. In addition, encapsulation significantly increased retention of phenolic compounds from 15.1-22.2% to 30.4-30.7% during baking (p&le / 0.05).
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Ultrasound Assisted Extraction Of Phenolics From Grape Pomace

Ozcan, Evren 01 January 2006 (has links) (PDF)
Grape pomace is a by-product of wineries. It is one of the most potent antioxidant sources due to its high phenolic content. In this thesis study, ultrasound assisted extraction of phenolic compounds from Merlot grape pomace has been studied. The effects of sonication time, subsequent extraction time in shaking water bath at 45&deg / C and composition of the solvent on extraction efficiency and recovery of phenolics were studied by response surface methodology. Folin-Ciocalteu colorimetric method was used to analyze effects of process parameters on the total phenolic content of the extracts. The best recovery (47.2 mg gallic acid equivalents of total phenolics per g of dried grape pomace) was obtained using 30 % aqueous ethanol and applying 6 minutes of sonication followed by 12 minutes of shaking in water bath at 45&deg / C.

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