Efeito da adição de argilas modificadas na estrutura e propriedades funcionais de biofilmes produzidos a base de zeína
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Data
2010-08-13
Autores
Tavares, Luciana Lopes [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O propósito deste estudo foi verificar alterações na estrutura e em algumas propriedades funcionais de biofilmes produzidos com zeína adicionados de argilas modificadas. As argilas modificadas Cloisite® 15A e Cloisite® 30B foram adicionadas na solução filmogênica sob agitação nas proporções de 1, 2 e 4% em relação à massa de zeína e os filmes formados pelo método “casting”. Ácido oléico e glicerol foram utilizados como agentes plasticizantes. Para a caracterização da microestrutura dos biofilmes foram realizadas as análises de Microscopia Eletrônica de Varredura (MEV), Ótica (MO) e Espectroscopia no Infravermelho (FTIR) e as propriedades funcionais avaliadas foram Opacidade, Solubilidade e Permeabilidade ao Vapor d’Água. Por meio das imagens obtidas na MEV observou-se que os acréscimos de argilas nos filmes resultaram na formação de uma microestrutura heterogênea, ou seja, estrutura de fase separada chamada de microcompósito ou tactóide, uma vez que as argilas não dispersaram no filme, o que proporcionou a formação de agregados. No entanto, por meio das imagens obtidas com a MO, observou-se uma distribuição uniforme dos glóbulos de lipídeos na matriz protéica, para todos os filmes. Em concordância com a característica da microestrutura dos filmes elaborados identificados na MEV, o FTIR foi capaz de identificar número de onda referente às argilas, indicando que a mesma não estabeleceu estruturação com a proteína, confirmando a formação de uma estrutura de fase separada tipo tactoide. Todos os filmes elaborados apresentaram maior opacidade quando comparados com o polietileno em razão da presença de pigmentos carotenóides. Pequenas diferenças na espessura das amostras e a quantidade de argila adicionada não influenciaram na transparência dos materiais. Os testes...
The purpose of this study was to evaluate changes in the structure and some functional properties of zein edible films added with modified clays. The modified clays Cloisite® 15A and Cloisite® 30B were added in the solution under agitation in the proportions of 1, 2 and 4% based on the weigh of zein. The films were formed pouring the solution on a surface to dry by casting method. Oleic acid and glycerol were used as plasticizer agents. Analyses of Scanning Electron Microscopy (SEM), Optical Microscopy (MO) and Infrared Spectroscopy (FTIR) were performed to characterize the microstructure of biofilms. The functional properties evaluated were opacity, solubility and permeability of water vapor. SEM images showed that the additions of clays in the films resulted in the formation of a heterogeneous microstructure, i.e. the phase separated structure called microcomposite or tactoids, since the clays were not dispersed in the film, which forms points of aggregates. However, the images obtained with MO showed an even distribution of lipids globules in the protein matrix, for all films. In agreement with the characteristic of the microstructure of the films showed by SEM, FTIR analyses pointed out the absence of wave number related to the clays, indicating that it was not established a really binding of the clays with the protein molecule. This confirms the formation of a material with phase separated, tactoid type. All the films prepared showed higher opacity when compared with polyethylene because of the presence of carotenoid pigments. Little differences in thickness of the samples and the amount of clay added did not influence the transparency of materials. Statistical mean tests of water solubility of the samples showed no differences among those films added with clay and the control. Water... (Complete abstract click electronic access below)
The purpose of this study was to evaluate changes in the structure and some functional properties of zein edible films added with modified clays. The modified clays Cloisite® 15A and Cloisite® 30B were added in the solution under agitation in the proportions of 1, 2 and 4% based on the weigh of zein. The films were formed pouring the solution on a surface to dry by casting method. Oleic acid and glycerol were used as plasticizer agents. Analyses of Scanning Electron Microscopy (SEM), Optical Microscopy (MO) and Infrared Spectroscopy (FTIR) were performed to characterize the microstructure of biofilms. The functional properties evaluated were opacity, solubility and permeability of water vapor. SEM images showed that the additions of clays in the films resulted in the formation of a heterogeneous microstructure, i.e. the phase separated structure called microcomposite or tactoids, since the clays were not dispersed in the film, which forms points of aggregates. However, the images obtained with MO showed an even distribution of lipids globules in the protein matrix, for all films. In agreement with the characteristic of the microstructure of the films showed by SEM, FTIR analyses pointed out the absence of wave number related to the clays, indicating that it was not established a really binding of the clays with the protein molecule. This confirms the formation of a material with phase separated, tactoid type. All the films prepared showed higher opacity when compared with polyethylene because of the presence of carotenoid pigments. Little differences in thickness of the samples and the amount of clay added did not influence the transparency of materials. Statistical mean tests of water solubility of the samples showed no differences among those films added with clay and the control. Water... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Alimentos - Embalagens, Argila - Industria, Biofilme, Zeína, Biofilms, Zein, Clays, Microcomposite
Como citar
TAVARES, Luciana Lopes. Efeito da adição de argilas modificadas na estrutura e propriedades funcionais de biofilmes produzidos a base de zeína. 2010. f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, 2010.