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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.
61

Caracterização química e estabilidade oxidativa de produto reestruturado de frango sob ação de embalagem ativa adicionada de extratos de resíduos agroindustriais / Chemical and oxidative stability of restructured chicken product stored under active packaging with addition of agro-industrial residues extracts

Leon, Juan Sebastian Serrano 13 July 2015 (has links)
A qualidade, aceitabilidade e a vida útil da carne de frango e principalmente seus produtos industrializados, dependem de vários fatores, sendo a oxidação lipídica um dos principais problemas de estabilidade do produto. O crescimento da tendência de consumo de compostos naturais por parte da população mundial e a demanda das indústrias de alimentos para controle da oxidação lipídica, surge como alternativa muito promissora a utilização de antioxidantes naturais. O Brasil, com uma grande produção de produtos vegetais e a economia fortemente baseada na agroindústria gera grandes quantidades de resíduos vegetais, sendo os resíduos de película de amendoim e pimenta-rosa potenciais fontes de antioxidantes. Estes resultados confirmados conforme ensaios preliminares in vitro, uma vez que são ricos em compostos bioativos, como compostos fenólicos. Além disto, a quitosana apresenta-se como uma boa matriz para incorporação de extratos contendo compostos bioativos, além de ter capacidade de formar filmes. Assim, o objetivo do estudo foi desenvolver filmes de quitosana com incorporação de antioxidantes naturais a partir dos extratos de resíduos de película de amendoim e pimenta rosa, e avaliar seu efeito sobre a oxidação lipídica em produto reestruturado de frango. O estudo foi dividido em três etapas: a primeira foi utilização da metodologia de superfície de resposta para determinação de uma concentração ótima de extrato de resíduo agroindustrial que incorporado ao filme de quitosana promova inibição da oxidação lipídica (valor de sustâncias reativas ao ácido tiobarbitúrico, TBARS). Na segunda etapa, foi avaliada a incorporação da concentração ótima dos extratos diretamente na carne e nos filmes ativos de quitosana, sobre as características físico-químicas (pH, cor instrumental, índice de peróxidos, e valor de TBARS) e microbiológicas dos tratamentos. Na terceira etapa foram avaliadas as características sensoriais e de aceitabilidade dos tratamentos que apresentaram menor oxidação lipídica. Os resultados revelaram que, na primeira etapa foram otimizadas as concentrações dos extratos de resíduos nos filmes ativos de quitosana. Os teores otimizados foram 80 mg de compostos fenólicos totais (CFT) / kg de carne para os resíduos de película de amendoim e de 90 mg CFT / kg de carne para pimenta rosa. Na segunda etapa, ao final do tempo de armazenamento, pode-se observar que não houve diferença significativa (p > 0,05) para os parâmetros de cor, pH e contagem de mesófilos totais. Para oxidação lipídica, todos os tratamentos apresentaram diferença significativa (p < 0,05), quando comparados com o controle. Para contagem de micro-organismos psicrotróficos totais houve diferença significativa para os tratamentos com filme ativo + extratos, quando comparados com os demais tratamentos. Na terceira etapa, os resultados mostraram que não houve diferença significativa na aceitabilidade entre os tratamentos. Adicionalmente também foi realizada uma caracterização sensorial com consumidores usando a metodologia Check-all-that-apply (CATA). Assim pode-se concluir que foram desenvolvidos filmes ativos de quitosana com adição de extratos de resíduos agroindustriais, com exelente potencial na atividade antioxidante e antimicrobiana em produtos carneos, sem influenciar na aceitabilidade sensorial. / Quality, accessibility, shelf life of chicken meat and mainly of its processed products depends on several factors, wherein lipid oxidation is a major stability product problem. The growth of the consumption trend of natural compounds by the world\'s population, and the demand from the food industry to control lipid oxidation appear as a very promising alternative to the use of natural antioxidants. Brazil, with a large production plant products and a strong economy based on agro-industry generates large amounts of crop residues where peanut shells and pink pepper residues are potential sources of antioxidants. According to preliminary in-vitro tests of these residues, these are rich in bioactive substances such as phenolic compounds. Moreover, chitosan presents itself as a good matrix for incorporation of extracts containing bioactive compounds, in addition to having the ability to form films. The aim of this study was to develop chitosan films incorporating natural antioxidants from peanut shells and pink pepper residues extracts, as well as to evaluate their effect on the lipid oxidation of a chicken restructured product. The study was divided into three stages: first was the use of response surface methodology to determine an optimal concentration of agro-industrial waste extract, which was incorporated into the chitosan film to promote inhibition of lipid oxidation (as an amount of reactive substances to thiobarbituric acid, TBARS). The second stage evaluated the incorporation of this optimal concentration of extracts applied directly in both the meat and the chitosan active films, in relation to the physicalchemical (pH parameters, instrumental color, peroxide value, and TBARS value) and microbiological characteristics of the treatments. The third stage evaluated the sensory characteristics and acceptability of treatments that had a lower lipid oxidation. The results revealed that the first stage optimized the concentrations of extracts from residues into the active chitosan films. The optimized concentration was 80 mg of total phenolic content (TPC) / kg of meat for peanut shells residue extract, and 90 TPC mg / kg of meat for the pink pepper extract. On the second stage, at the end of the storage time, it can be seen that there was no significant difference (p > 0.05) in parameters like color, pH and total mesophylls counts. For the lipid oxidation parameters, all treatments showed significant differences (p < 0.05) when compared with the control treatment. The microbial count of total psychrotrophic microorganisms showed significant differences for treatments with active films + residues extracts when compared with the other treatments. In the third stage, the results showed no significant difference in acceptability between treatments. Additionally, a sensory characterization with consumers using the Check-all-thatapply (CATA) methodology was also performed. Thus, it was concluded that the development of active chitosan films incorporated with extracts of agro-industrial waste was possible, which possess an antioxidant and antimicrobial potential activity without altering the sensory acceptability of the final product.
62

Extratos vegetais obtidos de espécies nativas do Cerrado brasileiro no controle do ácaro-rajado (Tetranychus urticae Koch) /

Agustini, José Antonio. January 2017 (has links)
Orientador: Marineide Rosa Vieira / Resumo: O ácaro rajado, Tetranychus urticae Koch, é uma praga que ataca várias culturas em todo o mundo. Seu controle é feito basicamente por acaricidas químicos sintéticos. O uso inadequado de defensivos agrícolas, além de acarretar problemas ao meio ambiente, ao trabalhador e ao consumidor, pode levar ao desenvolvimento de populações de pragas resistentes aos seus princípios ativos. Extratos vegetais têm sido estudados na busca de novos princípios ativos que causem menos problemas ambientais, ocupacionais e de saúde humana, e que possam fazer parte de programa de manejo integrado de pragas e doenças. As florestas brasileiras são constituídas por uma grande diversidade de plantas que podem apresentar metabólitos secundários interessantes com propriedades biocidas. O objetivo deste estudo foi avaliar extratos aquosos e hidroetanólicos de folhas e cascas de doze espécies vegetais nativas do Cerrado brasileiro quanto à atividade acaricida e ao efeito sobre a fecundidade de fêmeas do ácaro-rajado, T. urticae. De cada espécie vegetal foram avaliados dois órgãos (folhas e cascas), duas épocas de coletas (primavera/verão e outono/inverno) além de dois tipos de solventes (água e etanol 70%). Os extratos foram aplicados por pulverização em torre de Potter, avaliando-se mortalidade, repelência e oviposição após 120 horas. Todas as doze espécies apresentaram atividade acaricida significativa sobre T. urticae, dependendo da época de coleta, do material vegetal e do solvente utilizado. Em nove e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The two-spotted spider mite, Tetranychus urticae Koch, is a pest that attacks various crops throughout the world. The mites control is basically made by synthetic chemical acaricides. The inappropriate use of pesticides, besides causing problems to the environment, to the workers and the consumers, can lead to the development of populations of pests resistant to its active ingredient. Some pesticides such as neonicotinoids and pyrethroids have their origin in secondary plant metabolites such as tobacco and chrysanthemum, respectively. Plant extracts have been studied in the search for new active ingredients that cause less environmental, occupacional and human health problems, and that can be part of an integrated pest and disease management program. The Brazilian forests are constituted by a great plant diversity that can have interesting secondary metabolites with biocide properties. The objective of this study was to evaluate the mitecide activity of the aqueous and hydroethanolic extracts of leaves and bark of twelve native species from the Brazilian Cerrado and their effect on the fecundity of T. urticae mite females. Two plant organs (leaves and barks), two collection seasons (spring/summer and autumn/winter) were evaluated from each plant species, besides two types of solvents (70% ethanol and water). The extracts were applied by Potter tower spray, evaluating mortality, repellency and oviposition after 120 hours. All twelve species showed significant miticide activity... (Complete abstract click electronic access below) / Mestre
63

Desenvolvimento tecnológico de extratos vegetais padronizados a partir da Lafoensia pacari A. St.-Hill (Lythraceae) / Tecnhnological development of standard plant extracts from Lafoensia pacari A.St-Hill (Lythraceae)

Cardoso, Natasha Queiroz 28 February 2013 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2014-09-09T12:33:09Z No. of bitstreams: 2 Dissertacao Natasha Queiroz Cardoso.pdf: 6356540 bytes, checksum: 9b1301eb1ac2488f6b8f0123c7dfeae7 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-09T12:33:09Z (GMT). No. of bitstreams: 2 Dissertacao Natasha Queiroz Cardoso.pdf: 6356540 bytes, checksum: 9b1301eb1ac2488f6b8f0123c7dfeae7 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-02-28 / Lafoensia pacari A. St.-Hill (Lythraceae) popularly known as dedaleiro, didal, or mad-mangabeira pacari, is used by the Brazilian population as a febrifuge, tonic and healing. Studies have shown the antioxidant, anti-inflammatory, and antinoceptiva antiedematogenic extracts from the stem bark, ellagic acid being one of those responsible for the same. This study aimed to obtain dry extract standardized technology from the stem bark of L. pacari. The drug was tested for various quality control tests, according to the Brazilian Pharmacopoeia 5th edition, which ensured the characterization of plant drug and subsequently obtaining the liquid and dry extracts standardized. The extraction method was chosen slow percolation with 80% hydroalcoholic solution as a solvent and velocity of 7 drops per min .. The liquid extract standardized had a density of 0.986 g / mL solids content of 12.49% (w / w), pH 3.53 and an alcohol content of 44.80% (v / v). The content of ellagic acid found in liquid extract was 3.84% (m / m). The spray drying / atomization was performed by experimental design of univariate and then by planning a fractional 5-2 with 2 replicates. During the process the adjuvants were used maltodextrin and aerosil, demonstrating that the optimal conditions found maltodextrin provides greater protection and ellagic acid concentration in the extract. / Lafoensia pacari A. St.-Hill (Lythraceae) é conhecida popularmente como dedaleiro, didal, mangabeira-brava ou pacari, é utilizada pela população brasileira como febrífugo, cicatrizante e tônico. Estudos comprovaram as atividades antioxidante, antiinflamatória, antinoceptiva e antiedematogênica dos extratos provenientes das cascas do caule, sendo o ácido elágico um dos responsáveis pelas mesmas. O presente trabalho teve como objetivo a obtenção tecnológica de extrato seco padronizado a partir da casca do caule de L. pacari. A droga vegetal foi testada por diversos ensaios de controle de qualidade, de acordo com a Farmacopéia Brasileira 5ª edição, que garantiram a caracterização da droga vegetal e posteriormente a obtenção dos extratos líquidos e secos padronizados. O método de extração escolhido foi a percolação lenta com solução hidroalcóolica 80% como solvente e velocidade de 7 gotas por min.. O extrato líquido padronizado apresentou densidade de 0,986 g/mL, teor de sólidos de 12,49 % (m/m), pH 3,53 e teor alcoólico de 44,80% (v/v). O teor de ácido elágico encontrado no extrato líquido foi de 3,84%(m/m). A secagem por nebulização/atomização foi realizada por planejamento experimental de univariada e em seguida pelo planejamento fracionário 2 5-2 com replicatas. Durante o processo os adjuvantes utilizados foram a maltodextrina e o aerosil, demonstrando que nas condições ótimas encontradas a maltodextrina apresenta maior proteção e concentração de ácido elágico no extrato.
64

EFFECT OF STARCH-POLYPHENOL INTERACTIONS ON STARCH HYDROLYSIS

Guzar, Igor 08 January 2013 (has links)
Phenolic compounds have attracted much attention due to numerous health benefits, including high antioxidant properties, reduced risk of cancer, and inhibition of digestive enzymes. Recent research has suggested that different phenolic compounds may interact with starch. The first objective was to investigate the effect of green or black tea extracts on hydrolysis of wheat, rice, corn, and potato starches. Cooking starches in the presence of either tea reduced their hydrolysis. Potato starch cooked with black tea was the most effective treatment. Observations suggested that hydrolysis may be affected by interactions and by impact on specific enzymes based on starch structure. The second objective was to determine if similar effect could be observed in product system. Addition of green tea extract to sponge cake significantly reduced in vitro starch digestibility, thus could reduce the expected glycemic index. In addition, significant increases in dietary fibre, resistant starch, and antioxidant properties were observed.
65

PRODUÇÃO DE SALAME TIPO ITALIANO ATRAVÉS DE CURA NATURAL COM EXTRATOS DE AIPO E ACELGA / ITALIAN SALAMI PRODUCTION BY NATURAL CURING USING CELERY AND SWISS CHARD EXTRACTS

Biasi, Vanessa 17 December 2010 (has links)
The meat industry is always alert to consumer s requirements. Consumer s are now in search for healthier products, once they are changing their food habits. The sodium nitrite and other chemical preservatives are related to diseases such as cancer and, because of that, food products without the use of cure agents, or naturally cured, are being largely studied. From vegetable extracts and a nitrate reducing starter culture can prepare cured meat products similar to the conventionally cured. The objective of this research was to develop and evaluate the quality of Italian salami produced by natural curing, using celery and Swiss chard extracts as nitrate source, with or without a nitrate reducing starter culture. Six treatments were evaluated (T1 0,8% celery extract and pre-incubated starter culture; T2 0,8% celery extract and no incubated starter culture; T3 1,2% celery extract and pre-incubated starter culture; T4 0,3% celery extract; T5 0,3% celery extract and pre-incubated starter culture; T6 0,3% Swiss chard and pre-incubated starter culture) and a control (sodium nitrate and sodium eritorbate). Physical-chemical analysis (pH, proximate composition, water activity, sodium nitrite and nitrate, color and TBARS (thiobarbituric test)), microbiological analysis (coliforms at 45ºC, Staphylococcus coagulase-positive, Salmonella sp., sulfite-reducing Clostridium and lactic acid bacteria) and sensory evaluation were done during the maturation period at 0, 1, 4, 7, 10, 15 and 32 days. During the storage period, the oxidative activity (TBARS) and the color of the salami, at 30, 60 and 90 days were evaluated. All treatments showed a development of the typical color of cured meat products and the physical-chemical and microbiological results corresponded to the Brazilian official food regulations. In the sensorial analyses, all treatments were considered worst than control, although treatments T4, T5 and T6 were considered acceptable. The attribute considered most different by the testers was the flavor followed by the odor. During the storage period, the color of the treatments was considered similar to the control, but evaluating the a* values, no color stability was observed in the treatments that used lower extract concentrations, and these values were higher in the treatments than the ones used in the pre-incubated starter culture. Meanwhile, for the color development the pre-incubation time was not necessary. At the end of the storage period, the control showed the highest TBARS value, demonstrating that the vegetable extracts used had an anti-oxidation effect. / A indústria cárnea está sempre atenta às exigências dos consumidores, e na busca por produtos saudáveis, uma vez que consumidores estão mudando seus hábitos alimentares. O nitrito de sódio é usualmente utilizado como conservante químico e está relacionado com doenças como o câncer, por isso, produtos elaborados sem a adição desse agente de cura, ou naturalmente curados, estão tendo uma ampla atenção. A partir de extratos vegetais e uma cultura starter nitrato-redutora, podem-se obter produtos cárneos similares aos curados convencionalmente. O objetivo deste trabalho foi desenvolver e avaliar a qualidade de salames tipo Italiano produzidos por cura natural, utilizando extratos de aipo e acelga como fontes de nitrato, adicionados ou não de culturas starters nitrato-redutoras. Avaliaram-se seis tratamentos (T1 - 0,8% de extrato de aipo e cultura starter pré-incubada; T2 - 0,8% de extrato de aipo sem incubação da cultura starter; T3 - 1,2% de extrato de aipo e cultura starter pré-incubada; T4 - 0,3% de extrato de aipo; T5 - 0,3% de extrato de aipo e cultura starter pré-incubada e T6 - 0,3% de extrato de acelga e cultura starter pré-incubada) e um controle (nitrato de sódio e eritorbato de sódio). Realizaram-se análises físico-químicas (pH, composição centesimal, atividade de água, nitrito e nitrato de sódio, cor e TBA (teste do ácido tiobarbitúrico), análises microbiológicas (coliformes a 45ºC, Staphylococcus coagulase positiva, Salmonella sp., clostrídios sulfito-redutores e bactérias lácticas) e análise sensorial. Após 30, 60 e 90 dias de armazenamento, foram avaliadas a estabilidade à oxidação lipídica (TBA) e os parâmetros de cor dos salames. Todos os tratamentos apresentaram desenvolvimento de cor típica de produto curado e os resultados físico-químicos e microbiológicos atenderam aos padrões da Legislação Brasileira. Sensorialmente todos os tratamentos foram considerados inferiores ao controle, porém, aceitáveis para os tratamentos T4, T5 e T6. O atributo mais prejudicado foi o sabor, seguido do odor. Durante o período de armazenamento, a cor dos tratamentos manteve-se de maneira semelhante à do controle, porém, avaliando os valores de a*, não apresentou estabilidade nos tratamentos com as menores concentrações de extratos, e estes valores foram superiores nos tratamentos onde houve pré-incubação da cultura starter. Entretanto, para a formação da mesma, não é necessário o tempo de pré-incubação da cultura starter. No final do armazenamento, o tratamento controle apresentou maiores valores de TBA, mostrando a eficiência dos extratos vegetais como antioxidantes.
66

Cecropia pachystachya Trécul como adjuvante no tratamento do diabetes melito

Aragão, Danielle Maria de Oliveira 27 February 2015 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-04-27T15:30:59Z No. of bitstreams: 1 daniellemariadeoliveiraaragao.pdf: 4293901 bytes, checksum: 9fe0e48b323213abc9a30b33ba1f90db (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-12T15:50:14Z (GMT) No. of bitstreams: 1 daniellemariadeoliveiraaragao.pdf: 4293901 bytes, checksum: 9fe0e48b323213abc9a30b33ba1f90db (MD5) / Made available in DSpace on 2017-05-12T15:50:14Z (GMT). No. of bitstreams: 1 daniellemariadeoliveiraaragao.pdf: 4293901 bytes, checksum: 9fe0e48b323213abc9a30b33ba1f90db (MD5) Previous issue date: 2015-02-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Diabetes melito engloba uma série de alterações metabólicas que acarretam um estado crônico de hiperglicemia. Buscando novas alternativas para seu tratamento, muitas espécies de plantas conhecidas na medicina popular pelas propriedades hipoglicemiantes têm sido avaliadas. Entre essas espécies está Cecropia pachystachya Trécul (URTICACEAE), uma planta nativa do Brasil, cujos nomes populares são embaúba, imbaíba, umbaúba, árvore-de-preguiça, barbeira, torém. Nesse contexto, o presente estudo teve como objetivo avaliar o potencial hipoglicemiante, antioxidante e toxicológico das folhas de Cecropia pachystachya. Inicialmente foram preparados dois extratos das folhas dessa espécie, metanólico (EM) e em acetato de etila (EAE). Ambos os extratos foram submetidos à análise quantitativa dos marcadores moleculares e, posteriormente, foi avaliado o efeito hipoglicemiante de cada um deles. EAE foi ncorporado a uma formulação farmacêutica líquida (FF). EM, EAE e FF foram utilizados para o tratamento de ratos da linhagem Wistar normais e induzidos ao diabetes por estreptozotocina. A evolução desses tratamentos foi avaliada através de medidas mensais de glicemias de jejum, além de acompanhamento de peso corporal e consumos de água e ração. Ao final de seis meses, os animais foram eutanasiados e amostras de sangue e órgãos foram coletadas para análises bioquímicas, antioxidante e histopatológica. Foram ainda avaliados os efeitos de FF após a interrupção do tratamento e o efeito do pré-tratamento com FF na indução de ratos com estreptozocina. A análise do perfil cromatográfico de EM e EAE revelou a presença de três marcadores moleculares, ácido clorogênico, isoorientina e orientina. Na análise quantitativa foram observados maiores teores dos flavonoides isoorientina e orientina em EAE. Os extratos padronizados foram administrados em ratos diabéticos ao longo de seis meses, mostrando reduções significativas tanto para EM (56%) quanto para EAE (69%). No entanto, EAE apresentou redução significativa da glicemia já no primeiro mês de tratamento, além de apresentar resultados relevantes em todos os parâmetros antioxidantes avaliados. O tratamento crônico com FF proporcionou uma redução de aproximadamente 70% da glicemia de jejum, ao final dos seis meses, em relação à glicemia inicial desses mesmos animais. Após a interrupção desse tratamento, as glicemias de animais diabéticos foram mantidas em níveis normais. Além disso, o pré-tratamento de ratos normais com FF promoveu proteção sobre as células B-pancreáticas durante a indução do diabetes utilizando estreptozocina. Os resultados mostraram que a FF desenvolvida a partir da espécie Cecropia pachystachya pode ser indicada na preparação de um fitoterápico para auxiliar no tratamento do diabetes melito. / Diabetes mellitus comprises a series of metabolic changes that lead to a chronic state of hyperglycemia. Seeking new alternatives for their treatment, many species of plants known in folk medicine for hypoglycemic properties have been evaluated. Among these species is Cecropia pachystachya Trécul (Urticaceae), a plant native to Brazil, whose common names are embaúba, imbaíba, umbaúba, tree-of-laziness, barbeira, Torem. In this context, the present study aimed to evaluate the potential hypoglycemic, antioxidant and toxicology of Cecropia leaves pachystachya. Initially were prepared two extracts from the leaves of this species, methanol (EM) and ethyl acetate (EAE). Both extracts were subjected to quantitative analysis of molecula markers and subsequently evaluated the hypoglycemic effect of each. EAE was incorporated into a liquid pharmaceutical formulation (FF). MS, EAE and FF were used for the treatment of normal Wistar rats and streptozotocin-induced diabetes. The evolution of these treatments was evaluated through monthly measurements of fasting glucose, and body weight monitoring and water and feed consumption. After six months, the animals were euthanized and blood samples and organs were collected for biochemical, antioxidant and histopathological analysis. We also assessed the effects of FF after discontinuation of treatment and the effect of pretreatment with inducing FF in rats with streptozocin. Analysis of the chromatographic profile of MS and EAE showed the presence of three molecular markers, chlorogenic, orientin and isoorientina acid. The quantitative analysis showed higher levels of flavonoids orientin isoorientina and in EAE. Standardized extracts were administered to diabetic rats over six months, showing significant reductions for both MS (56%) and against EAE (69%). However, EAE had a significant reduction of blood glucose in the first month of treatment, and provide relevant results in all evaluated parameters antioxidants. Chronic treatment with FF was reduced by approximately 70% of fasting glucose at the end of six months from the initial blood glucose of those animals. After discontinuation of treatment, the glycemia of diabetic animals were maintained at normal levels. In addition, pretreatment of mice with normal FF provided protection for pancreatic B-cells in diabetes induced using streptozotocin. The results show that FF developed from Cecropia pachystachya species can be indicated in a herbal preparation to aid in the treatment of diabetes mellitus.
67

Caracterização química e estabilidade oxidativa de produto reestruturado de frango sob ação de embalagem ativa adicionada de extratos de resíduos agroindustriais / Chemical and oxidative stability of restructured chicken product stored under active packaging with addition of agro-industrial residues extracts

Juan Sebastian Serrano Leon 13 July 2015 (has links)
A qualidade, aceitabilidade e a vida útil da carne de frango e principalmente seus produtos industrializados, dependem de vários fatores, sendo a oxidação lipídica um dos principais problemas de estabilidade do produto. O crescimento da tendência de consumo de compostos naturais por parte da população mundial e a demanda das indústrias de alimentos para controle da oxidação lipídica, surge como alternativa muito promissora a utilização de antioxidantes naturais. O Brasil, com uma grande produção de produtos vegetais e a economia fortemente baseada na agroindústria gera grandes quantidades de resíduos vegetais, sendo os resíduos de película de amendoim e pimenta-rosa potenciais fontes de antioxidantes. Estes resultados confirmados conforme ensaios preliminares in vitro, uma vez que são ricos em compostos bioativos, como compostos fenólicos. Além disto, a quitosana apresenta-se como uma boa matriz para incorporação de extratos contendo compostos bioativos, além de ter capacidade de formar filmes. Assim, o objetivo do estudo foi desenvolver filmes de quitosana com incorporação de antioxidantes naturais a partir dos extratos de resíduos de película de amendoim e pimenta rosa, e avaliar seu efeito sobre a oxidação lipídica em produto reestruturado de frango. O estudo foi dividido em três etapas: a primeira foi utilização da metodologia de superfície de resposta para determinação de uma concentração ótima de extrato de resíduo agroindustrial que incorporado ao filme de quitosana promova inibição da oxidação lipídica (valor de sustâncias reativas ao ácido tiobarbitúrico, TBARS). Na segunda etapa, foi avaliada a incorporação da concentração ótima dos extratos diretamente na carne e nos filmes ativos de quitosana, sobre as características físico-químicas (pH, cor instrumental, índice de peróxidos, e valor de TBARS) e microbiológicas dos tratamentos. Na terceira etapa foram avaliadas as características sensoriais e de aceitabilidade dos tratamentos que apresentaram menor oxidação lipídica. Os resultados revelaram que, na primeira etapa foram otimizadas as concentrações dos extratos de resíduos nos filmes ativos de quitosana. Os teores otimizados foram 80 mg de compostos fenólicos totais (CFT) / kg de carne para os resíduos de película de amendoim e de 90 mg CFT / kg de carne para pimenta rosa. Na segunda etapa, ao final do tempo de armazenamento, pode-se observar que não houve diferença significativa (p > 0,05) para os parâmetros de cor, pH e contagem de mesófilos totais. Para oxidação lipídica, todos os tratamentos apresentaram diferença significativa (p < 0,05), quando comparados com o controle. Para contagem de micro-organismos psicrotróficos totais houve diferença significativa para os tratamentos com filme ativo + extratos, quando comparados com os demais tratamentos. Na terceira etapa, os resultados mostraram que não houve diferença significativa na aceitabilidade entre os tratamentos. Adicionalmente também foi realizada uma caracterização sensorial com consumidores usando a metodologia Check-all-that-apply (CATA). Assim pode-se concluir que foram desenvolvidos filmes ativos de quitosana com adição de extratos de resíduos agroindustriais, com exelente potencial na atividade antioxidante e antimicrobiana em produtos carneos, sem influenciar na aceitabilidade sensorial. / Quality, accessibility, shelf life of chicken meat and mainly of its processed products depends on several factors, wherein lipid oxidation is a major stability product problem. The growth of the consumption trend of natural compounds by the world\'s population, and the demand from the food industry to control lipid oxidation appear as a very promising alternative to the use of natural antioxidants. Brazil, with a large production plant products and a strong economy based on agro-industry generates large amounts of crop residues where peanut shells and pink pepper residues are potential sources of antioxidants. According to preliminary in-vitro tests of these residues, these are rich in bioactive substances such as phenolic compounds. Moreover, chitosan presents itself as a good matrix for incorporation of extracts containing bioactive compounds, in addition to having the ability to form films. The aim of this study was to develop chitosan films incorporating natural antioxidants from peanut shells and pink pepper residues extracts, as well as to evaluate their effect on the lipid oxidation of a chicken restructured product. The study was divided into three stages: first was the use of response surface methodology to determine an optimal concentration of agro-industrial waste extract, which was incorporated into the chitosan film to promote inhibition of lipid oxidation (as an amount of reactive substances to thiobarbituric acid, TBARS). The second stage evaluated the incorporation of this optimal concentration of extracts applied directly in both the meat and the chitosan active films, in relation to the physicalchemical (pH parameters, instrumental color, peroxide value, and TBARS value) and microbiological characteristics of the treatments. The third stage evaluated the sensory characteristics and acceptability of treatments that had a lower lipid oxidation. The results revealed that the first stage optimized the concentrations of extracts from residues into the active chitosan films. The optimized concentration was 80 mg of total phenolic content (TPC) / kg of meat for peanut shells residue extract, and 90 TPC mg / kg of meat for the pink pepper extract. On the second stage, at the end of the storage time, it can be seen that there was no significant difference (p > 0.05) in parameters like color, pH and total mesophylls counts. For the lipid oxidation parameters, all treatments showed significant differences (p < 0.05) when compared with the control treatment. The microbial count of total psychrotrophic microorganisms showed significant differences for treatments with active films + residues extracts when compared with the other treatments. In the third stage, the results showed no significant difference in acceptability between treatments. Additionally, a sensory characterization with consumers using the Check-all-thatapply (CATA) methodology was also performed. Thus, it was concluded that the development of active chitosan films incorporated with extracts of agro-industrial waste was possible, which possess an antioxidant and antimicrobial potential activity without altering the sensory acceptability of the final product.
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Effects of Natural Antioxidants on Lipid Oxidation of Menhaden Oil

Baek, Naerin 25 January 2013 (has links)
Preventing oxidative deterioration of fish oil is a significant challenge for the food industry. Natural antioxidants are widely incorporated into foods and oils to prevent oxidation and extend shelf life. The goal of the study is to investigate the activity of novel antioxidants in menhaden oil and to develop optimum formulations containing mixed tocopherols to control oxidation of menhaden oil. Alpha tocopherol, gamma tocopherol, and delta tocopherol in menhaden oil were found at 0.18mg/g, 0.37mg/g, and 0.14mg/g, respectively, using HPLC analysis. Teng Cha extract effectively delayed oxidation of menhaden oil (MO) when stored at 40°C for eight days by measuring primary oxidation products and secondary oxidation products. The combinations of Teng Cha extract and rosemary extract and combinations of ascorbyl palmitate, citric acid, Teng Cha extract and rosemary extract more effectively improved stability of MO containing mixed tocopherols than Teng Cha extract alone at 40°C storage for eight days by measuring primary oxidation products and secondary oxidation products. From this study, Teng Cha extract can be used as a potential natural antioxidant in food industry, especially in combinations with rosemary extract and tocopherols, extending shelf life of menhaden oil. / Master of Science in Life Sciences
69

Grape-seed extract (oligomeric proanthocyanidin) or N-acetylcysteine antioxidant supplementation several days before and after an acute bout of plyometric exercise

Delport, Chris J. 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This thesis aims to determine whether supplementation with a grape-seed derived antioxidant, oligomeric proanthocyanidin (PCO) or the glutathione precursor, N-acetylcysteine (NAC) may prove beneficial as treatment for exercise induced muscle damage (EIMD) in athletes. In this double-blind cohort study, 21 healthy, uninjured male rugby-players in mid-season training phase, aged between 18 and 25 years were randomly divided into three treatment groups. Participants received 210 mg PCO, NAC or placebo treatment for 9 consecutive days. The study comprised a 6-day wash-out period (protocol days: -12 to -7), followed by a 6-day supplement loading period (protocol days: -6 to -1) a plyometric exercise intervention (protocol day 0) and continued supplementation for 2 days (protocol days: 1 to 2). The exercise intervention comprised 15 sets of 10 near maximal, vertical plyometric squat jumps. Blood samples and delayed onset of muscle soreness (DOMS) scores were collected on protocol days: -6, 0, 1 and 2. Assessments included serum creatine kinase (CK) activity, oxygen radical absorbance capacity (ORAC), malondialdehyde (MDA) and soluble vascular cell adhesion molecule-1 (sVCAM-1) concentrations over time as well as a differential circulating leukocyte count (neutrophils, lymphocytes, monocytes, eosinophils and basophils). Data analysis of CK activity revealed no significant differences between groups. However, PCO treatment prevented a significant peak in the CK response at 24 h (as seen in the placebo and NAC groups) when compared to baseline, pre and post readings (p<0.05). NAC supplementation significantly improved serum ORAC after the exercise intervention. By 48 h, serum ORAC had improved significantly from readings taken immediately post exercise (p<0.05) only in the NAC group. For all groups, absolute neutrophil counts peaked at 6 h post exercise from baseline or pre readings (p<0.05). In both NAC and placebo treated groups, neutrophil counts had decreased significantly in circulation by 24 h post exercise from the 6 h time-point (p<0.05). However, neutrophil counts only reached significantly lower levels by 48 h post exercise (p<0.05) in the group supplemented with PCO. The monocyte count also peaked significantly at 6 h post exercise when compared with other time-points before and after the exercise intervention (p<0.05) in all treatment groups. Neither antioxidant treatment significantly altered the responses of other leukocyte sub-populations, MDA or sVCAM-1 concentrations where main effects of plyometric exercise was evident. Although not statistically significant, a trend toward diminished sVCAM-1 expression with either antioxidant supplementation was apparent. These findings suggest that PCO supplementation (210mg/d) which includes a 7 day loading period may diminish plyometric EIMD by limiting (but not completely inhibiting) the neutrophil response. Secondary muscle damage may be prevented by partially blunting neutrophil infiltration, rather than only quenching free radicals released during the neutrophil oxidative burst. Furthermore, the finding that NAC supplementation improves serum ORAC only after exercise may provide added benefit when administered in combination with PCO. / AFRIKAANSE OPSOMMING: Hierde tesis is daarop gerig om vas te stel of aanvulling met ‘n druifsaadekstrak (DSE) gederiveerde antioksidant: pro-antosianiedoliese oligomeer (PSO), of die glutathione voorloopermolekule, N-asetielsistien (NAS) voordelig beskou kan word as behandeling vir atlete onderhewig aan spierskade veroorsaak deur oefening. Gedurende hierdie dubbelblinde kohort studie is 21 gesonde, manlike rugbyspelers sonder beserings tussen die ouderdom van 18 en 25 jaar in middel-seison fase ewekansig in drie behandelingsgroepe verdeel. Deelneemers het elk 210 mg PSO, NAS of placebo-aanvulling geneem vir nege agtereenvolgende dae. Die studie het bestaan uit ‘n 6-dag uitwasperiode (protokoldae: -12 tot -7), as ook ‘n 6-dag aanvullings periode (protokoldae: -6 tot -1), gevolg deur ‘n pliometriese oefeningsintervensie (protokol dag 0) en verdere aanvulling tot en met 2 dae na die oefening (protokol dae: 1 tot 2). Die oefeningsintervensie het 15 stelle van 10 naastenby maksimale, vertikale pliometriese hurkspronge behels. Bloedmonsters en vertraagde aanvang spierseerheid (VAS) tellings is op protokoldae: -6, 0, 1 en 2 geneem. Analiese het serum kreatien kinase (KK) aktiwiteit, suurstof radikaal absorpsie kapasiteit (SRAK), Malondialdahied (MDA) en oplospare vaskulêresel adhesie molekule-1 (oVAM-1) konsentrasie bepalings asook ‘n differentiële sirkulerende leukosiet seltelling ingesluit. KK aktiewiteit het geen merkwaardige verskil tussen groepe getoon nie. PSO aanvulling het wel gelei tot die voorkoming van ‘n merkwaardige piek in die KK response soos in die placebo en NAC behandelde groepe bevind is by die 24 h tydspunt in vergelyking met basislyn-, voor- en na-oefeningslesings (p<0.05). NAS het ‘n merkwaardige verbetering in serum SRAK getoon, maar eers teen 48 h na oefening. Slegs die NAS behandelde groep het op hierdie tydspunt ‘n betekenisvolle verbetering in SRAK getoon in vergelyking met lesings direk na oefening (p<0.05). Vir alle groepe is ‘n betekenisvolle toename in absolute neutrophiltellings waargeneem 6 h na oefening in vergelyking met basislyn- en vooroefeningslesings (p<0.05). Beide NAS en placebo-behandelde groepe het ‘n betekenisvolle afname in neutrophiltellings teen 24 h na oefening getoon in vergelyking met die 6 h tydspunt (p<0.05) maar met die PSO-behandelde groep word hierde afname eers teen 48 h waargeneem (p<0.05). Monosiettellings het in alle groepe 6 h na oefening ‘n betekinsvolle piek getoon (p<0.05). Waar slegs die hoofeffek van die pliometriese oefening betekenisvol was, het nie een van die twee antioksidant aanvullings ‘n merkwaardige verandering aan die respons van ander leukosiet sub-populasies, MDA of oVAM-1 konsentrasies getoon nie. Al kon statistiese beduidenheid nie bewys word nie, wil dit blyk dat ‘n verminderde oVAM-1 uitdrukking onstaan het in die geval van beide antioksidant-behandelde groepe. Tesame stel hierdie bevindinge voor dat PSO toediening (210mg/d) insluitende ‘n 7-dag aanvullingsperiode die vermoë verleen om die neutrophielrespons gedeeltelik te onderdruk (sonder om dit heeltemal te inhibeer) en sodoende spierskade verminder. Dus word verdere spierskade moontlik verlaag deur die voorkoming van neutrophil weefsel infiltrasie eerder as verwydering van reaktiewe spesies wat vrygestel word tydens oefening. Die bevinding dat NAS aanvulling serum SRAK eers na oefening merkwaardig verbeter, kan as voordelig beskou word, veral wanneer toegedien in samewerking met PSO om verdere spierskade te voorkom en herstelling vinniger te bewerkstellig.
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Control of Foodborne Pathogenic Bacteria Using Natural Plant Antimicrobials

Reyna-Granados, Javier Rolando January 2012 (has links)
Foodborne pathogens are a threat to public health worldwide. Because many consumers prefer natural compounds to synthetic additives, research on safe plant-derived compounds with antimicrobial activity against foodborne pathogens is vital. The aim of this investigation was to evaluate the antimicrobial activities of plant essential oils (oregano, cinnamon, lemongrass), their active components (carvacrol, trans-cinnamaldehyde, citral) and plant-extracts such as green tea, apple skin extract, black and decaffeinated black tea, grapes seed and pomace extracts against foodborne bacteria. Salmonella enterica serotype Typhimurium DT104, and serotype Newport, were selected conducting an antibiotic screening on 23 Salmonella isolates using seven antibiotics to determine antibiotic resistance. Listeria monocytogenes (strain 101M; beef and pork sausage isolate; resistant to antimicrobials in past investigations) was included to represent gram-positive bacteria. Escherichia coli O157:H7 virulent isolates (932- apple juice isolate; ATCC 35150- human isolate; F4637- sprouts isolate; used as a cocktail) were selected after conducting a Multiplex PCR over nine E. coli O157:H7 isolates to detect shiga-toxin 1 and 2 genes. All antimicrobials were evaluated in vitro in phosphate buffered saline. In general, all pathogens were more susceptible to essential oils and their active components, than powder extracts. The most active antimicrobials from each category were directly applied on foods. The activity of oregano oil (0.5%) and green tea (3%) was evaluated against S. Typhimurium on chicken and S. Newport on tomatoes and sprouts, and the results showed that oregano oil was more effective. In addition, baby spinach leaf samples inoculated with green fluorescent protein labeled S. Newport were examined under confocal scanning laser microscope before and after antimicrobial treatments. Antimicrobial experiments against L. monocytogenes on sprouts, ham and bologna, carvacrol at 0.5% and grape seed extract at 3% were used and carvacrol showed better activity. Antimicrobial activity against E. coli O157:H7 was tested on romaine lettuce, spinach and ground beef using oregano oil at 0.5% and green tea at 3%. Both compounds were effective showing no recovery of E. coli O157:H7 from lettuce and spinach; however, was not reduced in ground beef. Antimicrobial plant compounds have the potential for reducing foodborne pathogenic bacteria on/in various foods.

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