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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.
1

Development and characterization of peptide antioxidants from sorghum proteins

Xu, Shiwei January 1900 (has links)
Master of Science / Department of Grain Science and Industry / Yonghui Li / Antioxidants are widely used in food industries to delay lipid oxidation and prevent oxidative deterioration. In recent years, growing interests in developing safe and efficient antioxidants from natural sources due to the health-related risks associated with synthetic antioxidants. Recently, peptide antioxidants have drawn growing interests as since proteins are a macronutrient with various functionalities and high consumer acceptability. A lot of dietary proteins have been validated for their antioxidant potentials especially those obtained from animal proteins, nuts and pulses. Relatively less information is available on characterizing the antioxidant profile of cereal protein, and even less for sorghum protein. Sorghum is the fifth largest crop worldwide and is the third in United States. U.S. is leading in global sorghum production and distribution, and the state of Kansas is producing nearly half of U.S. sorghum. Currently, about one third of the U.S. sorghum is being used for ethanol production, resulting in more than 450 kilotons of by-products (e.g., DDGS) annually, which were often discarded or underutilized. DDGS is a premium protein source (~ 30% protein) that could be potentially modified into value-added products such as peptide antioxidants. In this study, relevant literatures detailing the extraction of cereal proteins, enzymatic hydrolysis of proteins, purification and characterization of hydrolysates, and evaluation of antioxidant profiles were extensively reviewed in Chapter 1. As preliminary experiments, sorghum kafirin protein was extracted from defatted sorghum white flour and hydrolyzed by 10 different types of enzymes from microbial, plant and animal sources. Hydrolysates prepared with Neutrase, Alcalase, and Papain displayed the most promising antioxidant activities as well as total protein recovery were primarily selected and investigated in depth described in Chapter 2, Chapter 3, and Chapter 4. The reaction conditions including substrate content, enzyme-to-substrate ratio, and hydrolysis time are critical parameters in producing peptides with desired activity and consistency, were therefore examined and optimized for each case of kafirin hydrolysates. The antioxidant capacity of the resulting hydrolysates was measured for antioxidant capacity through in vitro assays (DPPH, ABTS, ORAC, reducing power, and metal chelating) and then demonstrated in model systems (oil-in-water emulsion and ground meat). The fractions of hydrolysates possessing strongest activities were further fractionated by gel filtration and HPLC. Peaks representing the largest areas from HPLC were identified for major sequences by MALDI-TOF-MS. The experiment results indicated that all the three selected fractions of kafirin hydrolysates revealed excellent inhibition effects against oil and fat oxidations, which could be employed as tools to predict their performances in real food products. In addition, the structure studies showed that medium-sized hydrolysates of Neutrase (3 – 10 kDa) and Alcalase (5 – 10 kDa), and small-sized hydrolysates of Papain (1 – 3 kDa) exhibited relatively stronger activities. This study provided a workable processing method and critical reaction parameters for the production of peptide antioxidants from sorghum protein. The experiment results revealed that the sorghum peptide antioxidant could act through multiple mechanisms including free radical scavenging, metal ion chelation, hydrogen donating, and forming physical barriers to minimize the contact of oxidative agents to targets. These antioxidative peptides are a promising ingredient that can be potentially incorporated to food and feed products as alternatives to synthetic antioxidants or synergetic elements to nonpeptic antioxidants for protection of susceptible food ingredients. This study also made a positive impact to sorghum ethanol industry by guiding the conversion of sorghum protein-rich by-products into value-added antioxidant products as an additional revenue stream.
2

Use of Natural Antioxidants to Control Oxidative Rancidity in Cooked Meats

Vasavada, Mihir 01 May 2006 (has links)
The research in this dissertation focused on determining antioxidant effects of various natural antioxidants in cooked meat systems. Milk mineral (MM), spices, and raisin paste were used in cooked meat systems to verify their potential antioxidant properties. The MM study determined the antioxidant activity of 1.5% MM added to uncured cooked beef meatballs, and possible additive effects of MM in combination with 20-ppm or 40-ppm sodium nitrate in cooked beef sausages . There was no additive inhibition of lipid oxidation in samples containing 20-ppm or 40-ppm sodium nitrite plus 1.5% MM. Cooked meat yield was not different between control meatballs and those containing MM. As expected, treatments containing nitrite had higher redness (a*) values than samples without nitrite. The MM at 1.5% was a very effective antioxidant as compared to controls. The Garam Masala (GM) study determined the antioxidant effects and sensory attributes of the individual spices in an Indian spice blend GM in cooked ground beef, and possible additive antioxidant effects between Type I and Type II antioxidants. All spices had antioxidant effects on cooked ground beef, compared to controls without spices, with cloves being the most effective. All spices at their lowest effective recommended level effectively lowered the perception of rancid odor and rancid flavor in cooked ground beef as compared to control samples. As expected, most spices also imparted distinctive flavors to the cooked ground beef. Type II antioxidants (iron binding phosphate compounds) were more effective than individual Type I antioxidants (spices and butylated hydroxytoluene; BHT) in cooked ground beef. There was a positive additive antioxidant effect seen with rosemary + MM and rosemary + sodium tripolyphosphate (STPP) treatments as compared to individual rosemary treatment. There was no additive antioxidant effect observed for other combinations of spices with phosphate antioxidants. The raisin study was done to determine the antioxidant activity of raisin paste added to cooked ground beef, pork, and chicken. Thiobarbituric acid (TBA) values were measured using the distillation method, on the distillates, to avoid interference from sugar in the raisins. Beef, pork, and chicken flavor intensity, rancid flavor intensity, and raisin flavor intensity were evaluated by a trained sensory panel (n = 6). Addition of 2% raisin paste effectively inhibited rancid flavor development for 14 days after cooking in cooked ground beef, pork, and chicken. Sugar added at levels equivalent to that contributed by the raisins inhibited rancidity, probably due to antioxidant effects of Maillard browning products, suggesting that the antioxidant effect of raisins was due to their sugar content.
3

Identificação de carotenoides e quantificação de compostos bioativos e atividade antioxidante em frutos do gênero Spondias

Gondim, Perla Joana Souza 20 February 2012 (has links)
Submitted by Katiane Souza (katyane.souza@gmail.com) on 2016-03-24T00:24:20Z No. of bitstreams: 1 Arquivototal.pdf: 1582250 bytes, checksum: b0a83687a65d6a685571deee23f9239c (MD5) / Made available in DSpace on 2016-03-24T00:24:20Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 1582250 bytes, checksum: b0a83687a65d6a685571deee23f9239c (MD5) Previous issue date: 2012-02-20 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Umbu (Spondias tuberosa Arr Cam), umbu-caja (Spondias sp.) and cajarana do Sertão (Spondias sp.) are fruit tree species still in stage of domestication, which belong to the Anacardiaceae family, whose fruits are appreciated by the excellent sensorial quality, as well as an alternative source of income, due to the extractive exploitation of their fruit in the harvest season. The objective of this study was to evaluate the fruits of native genotypes of three species of the genus Spondias, umbu, umbu-caja and cajarana do Sertão (Spondias sp.) harvested in two maturity stages, from different areas of occurrence in the Paraiba and Rio Grande do Norte states, Brazilian Nortestern. After harvest, fruits were transported to the Laboratory of Biology and Technology Postharvest - CCA - UFPB, where it was carried out the physical and physicochemical evaluations. The contents of bioactive compounds, qualification of caratenoides, and total antioxidant activity (TAA) by ABTS and ORAC methods were conducted at the Center of Biotechnology and Fine Chemistry (CBQF) of the School of Biotechnology (ESB) at the Catholic University of Porto (UCP) - Porto, Portugal. Among the physical characteristics of the fruits stand out for high yield above 60% the umbu-caja and 80% the umbu. For the physicochemical characteristics, in umbu-caja it was observed values of SS of 11.86%, 1.05% AT, and the SS / TA ratio that was highlighted for the genotype G2, with the highest average 13.75. For umbu, the SS / TA ratio, the only the P11 genotype had an average below the minimum value (10.00) required by the Brazilian Standard of Identity and Quality (PIQ), standing out fruits of the genotypes P1 and P7 (Soledad - PB) and P17 (Juazeirinho - PB) with values higher than 16.00. Fruits from most genotypes (70.83%) are proper for fresh consumption, due to the acidity content below 1.0 g.100g-1 of citric acid, evidencing be an alternative to the fresh fruit market and for processing. The carotenoides were identified and quantified by HPLC and in these three species studied was found the following types: zeaxanthin, β- cryptoxanthin, and β-carotene, but this latter was not found in umbu-caja. The levels of total carotenoids in umbu-caja, and Spondias sp umbu Sertão were: 7.12, 2.46, and 1130.34 μg.100g-1, respectively. Zeaxanthin was the major constituent in these species evaluated, and the highest content was found in the full ripen cajarana do Sertão (Spondias sp) (463.67 μg.100g-1). The bioactive compounds directly responsible for antioxidant activity, in addition to the total carotenoids and their constituents were yellow flavonoids, in the cajarana do Sertão, and polyphenols, in umbu. These compounds provide a significant source of natural antioxidants to the diet of the population of the Semi-Arid. The ABTS method was adequate for quantification of the antioxidant activity in fruit of the genus Spondias. / O umbu (Spondias tuberosa Arr. Cam.), umbu-cajá (Spondias sp.) e a cajarana do Sertão (Spondias sp.) são espécies frutíferas ainda em estágio de domesticação, pertencentes à família Anacardeaceae, cujos frutos são muito apreciados pela excelente qualidade sensorial, além de constituírem fonte de renda alternativa, em decorrência do extrativismo de seus frutos, em época de safra. O objetivo deste trabalho foi avaliar frutos de genótipos nativos de três espécies do gênero Spondias, umbu, umbu-cajá e cajarana do Sertão (Spondias sp.), em dois estádios de maturação, provenientes de diferentes áreas de ocorrência dos Estados da Paraíba e Rio Grande do Norte. Após a colheita os frutos foram transportados ao Laboratório de Biologia e Tecnologia Pós-Colheita – CCA – UFPB, onde se realizou a caracterização física e físico-química dos frutos. O conteúdo de compostos bioativos, qualificação dos carotenoides e atividade antioxidante total (AAT) pelos métodos ABTS e ORAC foram realizados no Centro de Biotecnologia e Química Fina (CBQF) da Escola Superior de Biotecnologia (ESB) da Universidade Católica do Porto (UCP) – Porto Portugal. Dentre as características físicas dos frutos, se destacam pelo alto rendimento acima de 60% o umbu-cajá e de 80% o umbu. Para as características físico-químicas, no umbu-cajá foram observados valores médios de SS de 11.86%, AT de 1.05% e relação SS/AT que se destacou no genótipo G2, com a maior média 13.75. No umbu, para a relação SS/AT apenas o genótipo P11 obteve média inferior ao valor mínimo (10.00), exigido pelo Padrão de Identidade e Qualidade (PIQ), destacando-se os frutos dos genótipos P1 e P7 (Soledade – PB) e P17 (Juazeirinho – PB), com valores superiores a 16.00. A maioria dos genótipos avaliados (70,83%) é propícia ao consumo fresco, por apresentarem acidez titulável abaixo de 1,0 g.100g-1 de ácido cítrico, evidenciando ser uma alternativa para o mercado de frutas frescas, bem como para processamento. Os carotenoides foram identificados e quantificados por HPLC e nestas três espécies foram encontrados os seguintes carotenoides: zeaxantina, β-cryptoxantina e o β-caroteno, não sendo observada a ocorrência deste último no umbu-cajá. Os teores de carotenoides totais no umbu-cajá, umbu e cajarana do Sertão foram de: 12.07, 2.46 e 1130.34 μg.100g-1, respectivamente. A zeaxantina foi o constituinte majoritário nas espécies avaliadas, sendo encontrados em maior conteúdo na cajarana do Sertão no estádio maduro (463.67 μg.100g-1). Os compostos bioativos responsáveis diretamente pela atividade antioxidante, além dos carotenoides totais e seus constituintes foram os flavonoides amarelos, na cajarana do Sertão e os polifenóis, no umbu. Estes compostos constituem-se num aporte significativo de antioxidantes naturais para a dieta da população do Semiárido. O método ABTS se mostrou adequado para quantificação da atividade antioxidante em frutos do gênero Spondias.
4

Use of natural antioxidants in dairy and meat products: a review of sensory and instrumental analyses

Cottone, Elyse January 1900 (has links)
Master of Science / Food Science Institute, Human Nutrition / Koushik Adhikari / Oxidative deterioration is a significant contributing factor to the limited shelf life of foods containing lipids. The lipids in meats and dairy products make them susceptible to oxidation, limiting the amount of time that such products can be stored before a change in the sensory properties is evident. The use of rosemary oleoresin in meat products and fried foods has been extensively researched and used in commercialized foods. Since dry cheese and dairy products also contain lipids that are highly susceptible to oxidation, the use of a natural rosemary oleoresin may be beneficial in increasing the shelf life and sensory acceptability of these products as well. The overall objective of this report was to review the uses of a natural antioxidant, rosemary oleoresin, to inhibit oxidation and sensory changes in dairy and meat products and determine which areas need further study.
5

Utilização de extratos comerciais derivados de plantas em produtos cárneos : avaliação da atividade antioxidante / Plant-derived commercial extracts on meat products : study on the antioxidant activity

Paglarini, Camila de Souza, 1989- 04 June 2015 (has links)
Orientador: Marise Aparecida Rodrigues Pollonio / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-27T13:09:44Z (GMT). No. of bitstreams: 1 Paglarini_CamiladeSouza_M.pdf: 1935100 bytes, checksum: aef936b63826838b7627e9db7c6d5e14 (MD5) Previous issue date: 2015 / Resumo: Os produtos cárneos são muito susceptíveis à oxidação lipídica, uma das principais reações de deterioração e a causa principal de sabor e odor desagradáveis, redução do valor nutricional e da vida útil, além da formação de compostos tóxicos. O consumo excessivo de produtos cárneos está relacionado com o aumento do risco de algumas doenças, tais como doenças cardiovasculares, câncer, hipertensão e obesidade e assim pesquisas vem sendo desenvolvidas para elaboração de produtos mais saudáveis, dentre os quais destacam-se aqueles com redução de aditivos sintéticos. Neste contexto, o objetivo do presente estudo foi avaliar a atividade antioxidante de extratos comerciais derivados de plantas em matéria-prima cárnea (carne de frango mecanicamente separada - CFMS) e em produto cárneo reestruturado elaborado com diferentes matérias-primas (carne bovina, suína, de frango e CFMS). As concentrações dos extratos naturais foram de 0,125, 0,25, 0,5 e 1,0%, m/m. Os extratos foram caracterizados quanto ao teor de compostos fenólicos, flavonóides totais, atividade antioxidante ORAC, DPPH e ABTS. A oxidação lipídica foi avaliada pela análise de substâncias reativas ao ácido tiobarbitúrico - TBARS. A matéria-prima cárnea foi avaliada crua em ambiente refrigerado (4 °C) nos dias 0, 2, 4, 6, 8 e 10 e o produto cárneo foi avaliado cozido refrigerado (4 °C) nos dias 0, 3 e 6 e cru congelado (-18 °C) nos dias 0, 30 e 60 de vida útil. Quando caracterizados, todos os extratos naturais apresentaram atividade antioxidante, com destaque para os extratos de semente de uva e chá verde. Na CFMS todos os extratos apresentaram potencial antioxidante, sendo que o extrato de romã foi o menos efetivo e assim não foi aplicado no produto cárneo. O extrato de chá verde foi o mais efetivo contra a oxidação nos hambúrgueres cozidos e crus. No entanto os extratos de semente de uva, alecrim e mate também aumentaram a vida útil dos hambúrgueres cozidos. Nos hambúrgueres congelados a vida útil foi aumentada pelos extratos de semente de uva e alecrim. Os extratos naturais apresentaram maior potencial antioxidante nos hambúrgueres quando comparados com o antioxidante sintético BHT. Os resultados obtidos sugerem que extratos comerciais derivados de plantas podem ser utilizados como antioxidantes naturais em produtos cárneos, no entanto, estudos sensoriais tornam-se necessários para viabilizar sua adição. Com relação à oxidação lipídica, é possível a utilização de extratos comerciais derivados de plantas em produtos cárneos, melhorando a sua qualidade nutricional / Abstract: Meat products are very susceptible to lipid oxidation, a major degradation reaction and primary cause of off-flavors, reduction in the nutritional value and shelf life, and formation of toxic compounds. Increased consumption of meat products has been associated with a high risk of developing cardiovascular disease, cancer, hypertension and obesity. Therefore, several studies have focused on the manufacture of healthier products, among which the products with less synthetic additives have stood out. In this context, the aim of this study was to evaluate the antioxidant activity of plant-derived commercial extracts on meat raw materials (mechanically separated poultry - MSP) and restructured meat product made with different raw materials (beef or pork or chicken or MSP). The natural extracts concentrations were 0.125, 0.25, 0.5, and 1.0% w / w. The extracts were characterized for phenolics content, total flavonoids, and antioxidant activity using ORAC, DPPH, and ABTS assays. Lipid oxidation was evaluated by measuring thiobarbituric acid reactive substances - TBARS. The chilled (4 °C) fresh raw material was evaluated at days 0, 2, 4, 6, 8, and 10, while the cooked product (4 °C) was evaluated at days 0, 3, and 6, and the fresh frozen product (-18 °C) was evaluated at days 0, 30 and 60 of storage. All natural extracts exhibited antioxidant activity, especially the grape seed and green tea extracts. In the MSP, all extracts presented antioxidant potential, and the pomegranate extract was less effective and therefore has not been used in the product formulation. The green tea extract was the most effective against oxidation in cooked and raw burgers. However, the grape seed, rosemary, and mate extracts also increased shelf life of the cooked burgers. With respect to the frozen hamburgers, the shelf life was also increased by grape seed and rosemary extracts. A higher antioxidant potential of the natural extracts was observed when compared to the synthetic antioxidant BHT. The results suggest that despite commercial plant-derived extracts can be used as natural antioxidants in meat products, sensory studies are necessary to enable their addition. With regard to lipid oxidation, it is possible to use commercial plant-derived extracts in meat products, improving nutritional quality / Mestrado / Tecnologia de Alimentos / Mestra em Tecnologia de Alimentos
6

Influência de antioxidantes naturais sobre o perfil lípidico de hambúrgueres bovinos submetidos à irradiação por 60CO e aceleradores de életrons / INFLUENCE OF NATURAL ANTIOXIDANTS ON LIPID COMPOSITION OF BEEF BURGERS SUBMITTED TO IRRADIATION IN 60CO SOURCE AND ELETRON BEAMS

Reginaldo Almeida da Trindade 27 March 2007 (has links)
A irradiação de carnes e seus derivados têm sido empregada em alguns países como medida de tratamento para garantir a segurança microbiológica destes produtos evitando infecções alimentares. A irradiação pode provocar algumas mudanças indesejáveis na composição química dos alimentos tal como a oxidação lipídica. Na produção de derivados de carnes, o perfil lipídico está diretamente relacionado com a qualidade sensorial e nutricional do produto. Para retardar o processo da oxidação lipídica são utilizados antioxidantes, que podem ser sintéticos ou naturais. Atualmente, maior atenção tem sido dada aos antioxidantes naturais derivados de ervas e especiarias, tais como o alecrim e o orégano. O objetivo deste trabalho foi avaliar o potencial antioxidante dos extratos destas duas especiarias em hambúrgueres bovinos submetidos à irradiação por fonte de 60CO com a dose de 6, 7 e 8 kGy e aceleradores de elétrons com dose de 3,5 e 7 kGy e estocados sob congelamento por períodos pré-estabelecidos de 0, 45 e 90 dias. Os resultados demonstraram que o alecrim apresentou maior proteção antioxidante em uma matriz alimentícia heterogênea como o hambúrguer, porém o orégano quando utilizado em sinergismo com o alecrim ou com o BHT/BHA conseguiu retardar a oxidação lipídica durante todo o período de análise. Apesar de terem ocorrido alterações no perfil de ácidos graxos não foi possível demonstrar uma linearidade dependente da dose de irradiação e/ou do tempo de estocagem. A análise sensorial mostrou que dentre as amostras formuladas com antioxidantes naturais, o orégano recebeu maiores notas entre os provadores. A amostra irradiada formulada com alecrim recebeu maior nota em relação a não-irradiada. O uso de especiarias com atividade antioxidante com o objetivo de inibir a degragação oxidativa em alimentos gordurosos mostra-se promissor para a aplicação industrial. / Radiation processing has been employed in some countries as a mean of treatment to assure microbiological safety of meat and meat products, avoiding the occurrence of food-borne disease. The ionizing radiation may cause some undesirable changes on chemistry composition of food and the lipid oxidation is one of the main reactions. In meat products processing industry, the lipid composition is directly related to nutritional and sensory quality of the product. For preventing oxidation, use of antioxidants which can be synthetic or natural, has been practically applied in some products. Currently, most attention has been given to natural antioxidants from herbs and spices like rosemary and oregano. The aim this study was to assess the antioxidant effects of either rosemary and oregano extract in beef burgers submitted to irradiation in 60Co source with dose 6, 7 e 8 kGy, electron beams with dose 3,5 e 7 kGy and storage under freeze along 0, 45 e 90 days. The results showed that rosemary extract has the major antioxidant effects when it is used on heterogeneous food matrix like beef burger, but oregano extract was better efficient to delay lipid oxidation along storage time when it is used in synergism with rosemary and/or BHT/BHA. Although to have occurred changes in the fatty acids composition it was not possible to demonstrate a straight dependence of irradiation dose and/or storage time. Sensory analysis showed that between the samples prepared with natural antioxidants, the beef burger prepared with oregano has received better scores by panelists. Irradiated beef burger prepared with rosemary has received better scores when compared to non-irradiated one. The use of spices with antioxidant activity to avoid the oxidative damage in foods that contain fats in their formulation is thought to be promising to application in food facilities.
7

Influência de antioxidantes naturais sobre o perfil lípidico de hambúrgueres bovinos submetidos à irradiação por 60CO e aceleradores de életrons / INFLUENCE OF NATURAL ANTIOXIDANTS ON LIPID COMPOSITION OF BEEF BURGERS SUBMITTED TO IRRADIATION IN 60CO SOURCE AND ELETRON BEAMS

Trindade, Reginaldo Almeida da 27 March 2007 (has links)
A irradiação de carnes e seus derivados têm sido empregada em alguns países como medida de tratamento para garantir a segurança microbiológica destes produtos evitando infecções alimentares. A irradiação pode provocar algumas mudanças indesejáveis na composição química dos alimentos tal como a oxidação lipídica. Na produção de derivados de carnes, o perfil lipídico está diretamente relacionado com a qualidade sensorial e nutricional do produto. Para retardar o processo da oxidação lipídica são utilizados antioxidantes, que podem ser sintéticos ou naturais. Atualmente, maior atenção tem sido dada aos antioxidantes naturais derivados de ervas e especiarias, tais como o alecrim e o orégano. O objetivo deste trabalho foi avaliar o potencial antioxidante dos extratos destas duas especiarias em hambúrgueres bovinos submetidos à irradiação por fonte de 60CO com a dose de 6, 7 e 8 kGy e aceleradores de elétrons com dose de 3,5 e 7 kGy e estocados sob congelamento por períodos pré-estabelecidos de 0, 45 e 90 dias. Os resultados demonstraram que o alecrim apresentou maior proteção antioxidante em uma matriz alimentícia heterogênea como o hambúrguer, porém o orégano quando utilizado em sinergismo com o alecrim ou com o BHT/BHA conseguiu retardar a oxidação lipídica durante todo o período de análise. Apesar de terem ocorrido alterações no perfil de ácidos graxos não foi possível demonstrar uma linearidade dependente da dose de irradiação e/ou do tempo de estocagem. A análise sensorial mostrou que dentre as amostras formuladas com antioxidantes naturais, o orégano recebeu maiores notas entre os provadores. A amostra irradiada formulada com alecrim recebeu maior nota em relação a não-irradiada. O uso de especiarias com atividade antioxidante com o objetivo de inibir a degragação oxidativa em alimentos gordurosos mostra-se promissor para a aplicação industrial. / Radiation processing has been employed in some countries as a mean of treatment to assure microbiological safety of meat and meat products, avoiding the occurrence of food-borne disease. The ionizing radiation may cause some undesirable changes on chemistry composition of food and the lipid oxidation is one of the main reactions. In meat products processing industry, the lipid composition is directly related to nutritional and sensory quality of the product. For preventing oxidation, use of antioxidants which can be synthetic or natural, has been practically applied in some products. Currently, most attention has been given to natural antioxidants from herbs and spices like rosemary and oregano. The aim this study was to assess the antioxidant effects of either rosemary and oregano extract in beef burgers submitted to irradiation in 60Co source with dose 6, 7 e 8 kGy, electron beams with dose 3,5 e 7 kGy and storage under freeze along 0, 45 e 90 days. The results showed that rosemary extract has the major antioxidant effects when it is used on heterogeneous food matrix like beef burger, but oregano extract was better efficient to delay lipid oxidation along storage time when it is used in synergism with rosemary and/or BHT/BHA. Although to have occurred changes in the fatty acids composition it was not possible to demonstrate a straight dependence of irradiation dose and/or storage time. Sensory analysis showed that between the samples prepared with natural antioxidants, the beef burger prepared with oregano has received better scores by panelists. Irradiated beef burger prepared with rosemary has received better scores when compared to non-irradiated one. The use of spices with antioxidant activity to avoid the oxidative damage in foods that contain fats in their formulation is thought to be promising to application in food facilities.
8

?leos essenciais e extratos vegetais de plantas cultivadas no Brasil: impacto no crescimento de Aspergillus ochraceus e Aspergillus carbonarius. 2010. / Brazilian essential oils and plant extracts: impact on growth of Aspergillus ochraceus and Aspergillus carbonarius. 2010.

Oliveira, ?guida Aparecida de 09 February 2010 (has links)
Made available in DSpace on 2016-04-28T20:15:37Z (GMT). No. of bitstreams: 1 Aguida Aparecida de Oliveira.pdf: 1420942 bytes, checksum: 1cc76cb0748d791233e6e8e7607e24e1 (MD5) Previous issue date: 2010-02-09 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Essential oils and plant extracts from aromatic plants are recognized for its antimicrobial properties and effectiveness as food antioxidants. The mycotoxins are toxic metabolites produced by filamentous fungi in feed, being particularly harmful to animals and humans. The mycotoxin occurrence happens after an oxidation process, consequently, the oxidation prevention is a way to avoid mycotoxins production, like ochratoxin A, which is a nephrotoxic toxin, mainly produced by Aspergillus ochraceus, Aspergillus niger and Aspergillus carbonarius in tropical areas. There is evidence that syntetic antioxidants can be prejudicial to animals and humans health. Thus, this study aimed to evaluate the effectiveness of Brazilian plant extracts (essential oils hydrodistillation and hexanic extraction; and vegetal extracts: aqueous and ethanolic) to inhibit the growth of A. ochraceus NRRL 3174 and A. carbonarius RC 2054 (UNRC). A total of 40 plant extracts from ten vegetable species: basil (Ocimum basilicum), cinnamon (Cinnamomum zeylanicum), clove (Eugenia caryophyllata), cumin (Cuminum cyminum), marjoram (Origanum majorana), nutmeg (Myristica fragrans), oregano (Origanum vulgare), rosemary (Rosmarinus officinalis), spearmint (Menta piperita) and sweet fennel (Pimpinella anisum) were screened by diffusion agar test for the best results on mycelial growth inhibition. Oregano essential oils (obtained by hydrodistillation and hexanic extraction), the rosemary essential oil and the clove ethanolic extract were chosen to obtain the growth rate and the lag phase at concentrations of 0, 50, 100, 150, 300 and 600 mg/kg on yeast extract-sucrose agar (YES). Strains were centrally inoculated and the radial growth (mm/day) was daily measured. The growth rate decreased as the essential oil concentration increased in all treatments and fungal strains assayed. The oregano essential oil showed the best results among the other essential oils. Comparing all four treatments, the best result was for clove ethanolic extract and the worst one was for oregano essential oil produced by hexanic extraction. The concentration of 600 mg/kg exerted the best inhibitory effect. These results are interesting related to the prevention of fungi contamination in many foods and they could be used instead of synthetic antifungal products. Future studies should be conducted to determine the ability of these oils and extracts to reduce the ochratoxin A production. / ?leos essenciais e extratos vegetais de plantas arom?ticas s?o reconhecidos por suas propriedades antimicrobianas e efici?ncia como antioxidante de alimentos. As micotoxinas s?o metab?litos t?xicos produzidos por fungos filamentosos em alimentos, sendo particularmente nocivas a animais e humanos. A ocorr?ncia de micotoxinas ocorre depois de um processo de oxida??o, consequentemente, a preven??o da oxida??o ? um meio de evitar a produ??o de micotoxinas, como a ocratoxina A, que ? uma toxina nefrot?xica, principalmente produzida por Aspergillus ochraceus, Aspergillus niger e Aspergillus carbonarius em ?reas tropicais. H? evid?ncias de que antioxidantes sint?ticos possam ser prejudiciais ? sa?de animal e humana. Assim, este estudo objetivou avaliar o efeito inibit?rio de plantas arom?ticas brasileiras (?leos essenciais obtidos por hidrodestila??o e extra??o hex?nica; e extratos vegetais: etan?lico e aquoso) sobre o crescimento de A. ochraceus NRRL 3174 e A. carbonarius RC 2054 (UNRC). Um total de 40 extratos de plantas oriundos de dez esp?cies vegetais: manjeric?o (Ocimum basilicum), canela (Cinnamomum zeylanicum), cravo (Eugenia caryophyllata), cominho (Cuminum cyminum), manjerona (Origanum majorana), noz moscada (Myristica fragrans), or?gano (Origanum vulgare), alecrim (Rosmarinus officinalis), hortel? (Menta piperita) e erva-doce (Pimpinella anisum) foram submetidos a uma sele??o pelo teste de difus?o em agar para eleger os que proporcionassem os maiores halos de inibi??o f?ngica. Os ?leos essenciais de or?gano (obtidos por hidrodestila??o e extra??o hex?nica), de alecrim (obtido por hidrodestila??o) e o extrato etan?lico de cravo foram os mais efetivos, e foram ent?o escolhidos para a obten??o dos par?metros de velocidade de crescimento e fase lag nas concentra??es de 0, 50, 100, 150, 300 e 600 mg/kg em placas de Petri contendo meio agar extrato de levedura e sacarose (yeast extract sucrose agar - YES); as cepas foram inoculadas no ponto central, e o crescimento radial da col?nia (mm/dia) foi mensurado diariamente. A velocidade de crescimento diminu?a ? medida que a concentra??o do ?leo essencial aumentava em todos os tratamentos e cepas testadas. O ?leo essencial de or?gano mostrou os melhores resultados dentre os ?leos essenciais. Comparando os quatro tratamentos, os melhores resultados foram obtidos com o extrato etan?lico de cravo, e os piores resultados com o ?leo essencial de or?gano obtido por extra??o hex?nica. A concentra??o de 600 mg/kg foi a de maior poder inibit?rio. Esses resultados s?o interessantes na conex?o com a preven??o do crescimento f?ngico em muitos alimentos, e poder?o ser usados em substitui??o dos produtos antif?ngicos sint?ticos. Mais estudos devem ser conduzidos para determinar a habilidade desses ?leos e extratos na redu??o da produ??o de ocratoxina A.
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Atividade antioxidante de extratos de própolis verde em sistemas lipídicos emulsionados / Antioxidant activity of extracts of green propolis in emulsified lipid systems

Cavalaro, Renata Iara 24 May 2017 (has links)
O uso de antioxidantes sintéticos pela indústria de alimentos como forma de inibir ou retardar a oxidação lipídica tem sido amplamente questionado em relação à saúde do consumidor. Por isso, diversos estudos são realizados visando sua substituição por antioxidantes de fontes naturais, como os obtidos a partir da própolis verde. Neste contexto, a forma de extração influencia a composição e a atividade antioxidante dos produtos derivados, sendo um processo a ser estudado visando a obtenção não somente da extração dos compostos de interesse como também de vantagens operacionais. Este trabalho apresenta uma revisão bibliográfica e experimentos sobre a reação da oxidação lipídica, bem como os antioxidantes sintéticos e naturais para substituição. Além disso, vários métodos de avaliação da capacidade e extração de antioxidantes, com atenção especial ao ultrassom, considerando que ainda não foi relatado em estudos com a própolis verde, apesar de ser considerado um dos melhores métodos de uso por alguns autores. Neste trabalho a extração de compostos antioxidantes de própolis verde com auxílio de ultrassom foi avaliada por meio da aplicação de delineamentos experimentais visando a otimização das condições de processo. Utilizou-se o delineamento central composto rotacional (DCCR) com 12 ensaios, sendo 4 pontos centrais para ambos os capítulos. Os extratos obtidos nas condições de processo otimizadas foram aplicados em emulsões lipídicas. No primeiro delineamento experimental analisado foram obervados efeitos significativos do tempo de processo e da proporção solvente:matéria prima sobre o teor de compostos fenólicos e atividade antioxidante, determinada pelo método ORAC, dos extratos obtidos. Por meio de análise por cromatografia líquida de alta eficiência (CLAE) pôde-se identificar que o aumento do tempo de extração e da proporção solvente:matéria prima influenciaram positivamente a extração do Artepelin C e do ácido p-cumárico. Buscando-se melhorar a produtividade do processo de extração, foi aplicado um segundo delineamento experimental, fixando-se a variável tempo em 20 minutos e variando-se a concentração de etanol e relação amostra:solvente. Os extratos produzidos com uso de etanol anidro (99% v/v) e proporção própolis:solvente de 0,857:30 m/v, apresentaram atividade antioxidante e teores de Artepelin C e ácido p-cumárico superiores aos encontrados nos extratos obtidos do experimento anterior, evidenciando a importância do estudo sequencial para otimização do processo de extração. Os extratos produzidos nas condições otimizadas foram aplicados em emulsões lipídicas submetidas a teste acerelado de oxidação. As amostras adicionadas de extrato de própolis verde apresentaram grau oxidativo semelhante àquela adicionada do antioxidante sintético TBHQ, muito utilizado pela indústria de alimentos e questionado quanto aos seus efeitos sob a saúde do consumidor. Os resultados indicaram que extrato de própolis verde obtido em condições otimizadas representam uma alternativa para uso como antioxidante em sistema lipídico. / Synthetic antioxidants, used by the food industry to inhibit or retard the oxidation, has been correlated with problems of consumer\'s health. Therefore, several studies are carried out to replace them by antioxidants from natural sources, such as a green propolis. In this context, the extraction form influences the composition and antioxidant capacity of the derived products, so it must be studied aiming not only the extraction of the compounds of interest, but also to obtain operational advantages. This work presents a bibliographical review and experiments about the reaction of lipid oxidation, as well as the synthetic and natural antioxidants for substitution. In addition, several methods of evaluating antioxidant capacity and extraction, with special attention to ultrasound, were discussed, which has not been reported in a study with a green própolis yet, despite of being considered one of the best methods of use by some authors. In this work the extraction of green propolis\'s antioxidant compounds with ultrasound was evaluated by the application of experimental designs to optimize the process conditions. The Central Composite Rotational Design (CCRD) was used with 12 essay and 4 central points for both chapters. The extracts obtained under the optimized process conditions were applied in lipid emulsions. In the first experimental design applied to extraction process, it was verified that variables time and the sample:solvente relation presented positive effects on phenolic content and antioxidant activity determined by ORAC method. Results of high performance liquid chromatography (HPLC) indicated that increasing time of extraction and sample:solvent proportion allowed a higher extraction of Artepelin C and p-coumaric acid. In order to obtain the optimal extraction condition, a second experiamental design was applied, aimimg to use as little sample as possible in a low extraction time. In this experiment, etanol concentration and sample:solvent relation were studied. Extracts obtained using 99% v/v etanol, 0.857: 30 m/v ratio during 20 minutes presents higher amounts of Artepelin C and p-coumaric acid compared to previous results. Extracts obtained under opmized condition was added to lipid emulsions subjected to accelerater oxidation test. The samples with propolis extracts presented peroxide values similar to samples added of TBHQ, a synthetic antioxidant widely used by the food industry and questioned due to its effects on consumer health. Results indicate propolis extracts represent a potential alternative to synthetic antioxidant for food use.
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ANTIOXIDANTE NATURAL DE MARCELA (Achyrocline satureioides) E DE ERVA MATE (Ilex paraguariensis) NA ELABORAÇÃO DE LINGÜIÇA TOSCANA / NATURAL ANTIOXIDANT OF YERBA MATE (Ilex paraguariensis) AND MARCELA (Achyrocline satureioides) IN AND THE DEVELOPMENT OF TUSCANY SAUSAGE

Brum, Eduardo Borges de 27 February 2009 (has links)
This study aimed to develop natural antioxidants of Achyrocline satureioides (marcela) and Ilex paraguariensis (yerba mate), in addition to tuscany sausage and porcine barth, with evaluation and determination of the best constitutions in the antioxidant activity and sensory characteristics of products. In the first experiment, was evaluated the effect of two levels (0,5% and 1%) of hydro-ethanolic extracts of marcela and yerba mate, and the mixed composition of extracts of marcela and yerba mate (1/1:v/v) in the inhibition of lipid oxidation and interference in the colorimetric (C Lab) of porcine barth. The antioxidant activity was high for all the extracts and compositions of mi6xed extracts. Values were observed between 91,86 and 99,15% of the inhibition of lipid oxidation in accelerated oxidation test and no significant difference (p>0,05) between treatments. There was no synergistic effect or antagonistic, the composition of mixed extracts of marcela and yerba mate (1/1:v/v) on the inhibition of oxidation. In the analysis of colorimetric coordinates a* and b*, yerba mate extract (1%) obtained the highest value, differentiating it significantly (p<0,05) of the others, indicating greater interference in the color of porcine barth. As for the L* coordinate, control, the mixed compositions of extracts (0,5% and 1%) and extract of marcela (0,5%) showed no significant difference (p>0,05), indicating no interference in the light of porcine barth. In the second experiment was to evaluate the effect of hydro-ethanolic extract and purified extract of marcela and yerba mate, added (0,5%) in tuscany sausage, with analysis of lipid stability (TBARS), quality (pH and sensory attributes) and microbiology (aerobic mesophiles, coliforms at 45 ºC/g, Staphylococcus coagulase positive, Clostridium Sulphite reducing to 46 ºC and Salmonella sp). All treatments showed lipid stability during storage at 4 ºC, except the control that has accelerated the process of oxidation from 30 days. There was no interference of the addition of the extracts on the pH of the sausages in comparison with the control. In sensory analysis the hydroethanolic extract of yerba mate interfere (p<0,05) compared to control. In the microbiological analysis during the period of storage, the count of Clostridium sulphite reducing to 46 C was less than 1x101 CFU. g-1, Staphylococcus coagulase positive was less than 1x102 CFU. g-1, coliforms at 45 º C was less than 1x101 CFU. g-1 and Salmonella was absent in 25g. The count of aerobic mesophiles for all treatments was lower than 106 CFU. g-1, during storage and sausages have slight variations, reducing the count of 12 days and progressive increases. At the end of the storage period from 30 days, there was a process of bacterial growth in all samples, except in sausages added hydro-ethanolic extract of marcela. The addition of 0,5% of purified extracts of yerba mate, or hydro-ethanolic, or purified from marcela can be used in the preparation of tuscany sausage and provide safer products for consumers. / Este trabalho teve como objetivo desenvolver antioxidantes naturais de Achyrocline satureioides (marcela) e de Ilex paraguariensis (erva mate), para adição em lingüiça toscana e banha suína, com avaliação e determinação das melhores constituições quanto à atividade antioxidante e características sensoriais dos produtos. No primeiro experimento, foi avaliado o efeito de dois níveis (0,5% e 1%) de extratos hidro-etanólicos de erva mate e de marcela, bem como da composição mista de extratos de erva mate e marcela (1/1:v/v), na inibição da oxidação lipídica e a interferência na colorimetria (CLab) da banha suína. A atividade antioxidante foi elevada para todos os extratos e composições mistas de extratos. Observaram-se valores entre 91,86 e 99,15% na inibição da oxidação lipídica, no teste de oxidação acelerada e não houve diferença significativa (p>0,05) entre os tratamentos. Não foi observado efeito sinérgico, nem antagônico, na composição mista de extratos de erva mate e de marcela (1/1:v/v) sobre a inibição da oxidação. Na análise da colorimetria das coordenadas a* e b*, o extrato de erva mate a 1% obteve o valor mais alto, diferenciando-se significativamente (p<0,05) dos demais, indicando uma maior interferência na cor da banha suína. Quanto à coordenada L*, o controle, as composições mistas de extratos (0,5% e 1%) e o extrato de marcela (0,5%) não demonstraram diferença significativa (p>0,05), indicando não haver interferência, na luminosidade, da banha suína. No segundo experimento foi avaliado o efeito do extrato hidro-etanólico e do extrato purificado de marcela e de erva mate adicionado (0,5%) em lingüiça toscana, com análise da estabilidade lipídica (TBARS), qualidade (pH e atributos sensoriais) e microbiologia (aeróbias mesófilos, coliformes a 45 ºC/g, Staphylococcus coagulase positiva, Clostridium sulfito redutores a 46 ºC e Salmonella sp). Todos os tratamentos apresentaram estabilidade lipídica durante o período de armazenamento a 4 °C, exceto o controle que sofreu aceleração do processo de oxidação a partir dos 30 dias. Não houve interferência da adição dos extratos sobre o pH das lingüiças em comparação com o controle. Na análise sensorial o extrato hidro-etanólico de erva mate interferiu (p<0,05) em comparação ao controle. Nas análises microbiológicas, durante o período de armazenamento a contagem de Clostridium sulfito redutores a 46 ºC foi menor que 1x101 UFC. g-1, Staphylococcus coagulase positiva foi menor que 1x102 UFC. g-1, coliformes a 45 º C foi menor que 1x101 UFC. g-1 e Salmonella sp foi ausente em 25g. A contagem de aeróbios mesófilos para todos os tratamentos foi inferior a 106 UFC. g-1, durante o armazenamento e as lingüiças sofreram ligeiras oscilações, com redução da contagem de aeróbios no dia 12 e progressivos aumentos. No final do período de armazenagem, a partir de 30 dias, houve um processo de crescimento bacteriano em todas as amostras, exceto em lingüiças adicionadas de extrato hidro-etanólico de marcela. A adição de 0,5% do extrato purificado de erva mate, ou hidro-etanólico, ou purificado de marcela pode ser utilizada na preparação de lingüiça toscana, fornecendo produtos mais seguros para os consumidores.

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