Características estruturais e funcionais de biofilmes produzidos com zeína e óleos vegetais comestíveis
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Data
2010-12-15
Autores
Almeida, Crislene Barbosa de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os objetivos deste trabalho foram produzir biofilmes de zeína adicionados de ácido oléico puro e óleos vegetais comestíveis com alto teor deste ácido graxo e determinar as propriedades estruturais e funcionais dos biomateriais produzidos. A análise da composição da zeína em pó utilizada indicou uma possível contaminação residual de lipídeos proveniente do glúten do milho. Os óleos comestíveis usados foram o óleo de buriti, que apresentou um menor teor de ácido oléico (35,1 %), comparado com os óleos de oliva e macadâmia (acima de 61 %). Para caracterizar a microestrutura dos biofilms, análises de Espectroscopia no Infravermelho por Transformada de Fourier (FTIR-ATR), Microscopia Eletrônica de Varredura (MEV), Microscopia Óptica (MO) e difração de Raios-X (WAXS) foram realizadas. As propriedades funcionais avaliadas foram opacidade, Permeabilidade ao Vapor d’Água (PVA), solubilidade em água, molhabilidade, isotermas de sorção, propriedades térmicas, mecânicas e permeabilidade a gases. As análises de FTIRATR sugeriram que os diferentes plasticizantes não afetaram a estrutura química e molecular da matriz de zeína. A MEV e a MO mostraram que o biofilme controle (zeína-ácido oléico) foi o mais homogêneo, em que, aparentemente, os ácidos graxos foram capazes de formar uma matriz mais coesa e contínua. Os poros observados na MEV foram posteriormente identificados, pela MO, como glóbulos de lipídeos. As análises de Difração de Raios-X (WAXS) mostraram que a estrutura da -hélice da zeína não foi modificada com a adição dos diferentes plasticizantes. A opacidade dos filmes aumentou com o aumento da concentração do ácido oléico. Os biofilmes elaborados com ácido oléico puro apresentaram os menores valores para PVA, solubilidade e molhabilidade, sendo, portanto, mais hidrofóbicos que os demais. Entretanto, as isotermas de umidade...
The aim of this work was to produce biofilms of zein added with oleic acid and others edible vegetable oils containing high level of this fatty acid, and determine the structural and functional properties of the biomaterials produced. The composition analyses of zein powder indicated a possible residual contamination of lipids from the corn. Fatty acid composition of edible oils used show that buriti oil had the lowest content of oleic acid (35.1 %) while the others oils (olive and macadamia) had above 61 %. To characterize the microstructure of the biofilms, analyses of Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Optical Microscopy (MO) and X-ray diffraction (WAXS) were performed. The functional properties were also evaluated through opacity, Water Vapor Permeability (WVP), solubility in water, wettability, sorption isotherms, Differential Scanning Calorimetric (DSC), thermogravimetry (TGA), mechanical behavior and gas permeability. FTIR-ATR spectra suggested that different plasticizers did not affect the chemical and molecular structure of zein matrix. The SEM and OM images showed that control biofilm (zeinoleic acid) was the most homogeneous, where apparently the fatty acids were able to form a more continuous matrix. The pores first observed in SEM were later identified by optical microscopy as lipids. Analyses of WAXS showed that -helix structure of the zein was not modified by the addition of different plasticizers. The opacity increased according to oleic acid concentration. Biofilms with oleic fatty acid showed the lowest values for WVP, solubility and wettability and were more hydrophobic than the others. However, the equilibrium moisture contents showed by the isotherms were not different for all types of plasticizers, in the same water activity. The equilibrium moisture data obtained for 5, 15, 25, 35 and 45 °C were adjusted by different mat... (Complete abstract click electronic access below)
The aim of this work was to produce biofilms of zein added with oleic acid and others edible vegetable oils containing high level of this fatty acid, and determine the structural and functional properties of the biomaterials produced. The composition analyses of zein powder indicated a possible residual contamination of lipids from the corn. Fatty acid composition of edible oils used show that buriti oil had the lowest content of oleic acid (35.1 %) while the others oils (olive and macadamia) had above 61 %. To characterize the microstructure of the biofilms, analyses of Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Optical Microscopy (MO) and X-ray diffraction (WAXS) were performed. The functional properties were also evaluated through opacity, Water Vapor Permeability (WVP), solubility in water, wettability, sorption isotherms, Differential Scanning Calorimetric (DSC), thermogravimetry (TGA), mechanical behavior and gas permeability. FTIR-ATR spectra suggested that different plasticizers did not affect the chemical and molecular structure of zein matrix. The SEM and OM images showed that control biofilm (zeinoleic acid) was the most homogeneous, where apparently the fatty acids were able to form a more continuous matrix. The pores first observed in SEM were later identified by optical microscopy as lipids. Analyses of WAXS showed that -helix structure of the zein was not modified by the addition of different plasticizers. The opacity increased according to oleic acid concentration. Biofilms with oleic fatty acid showed the lowest values for WVP, solubility and wettability and were more hydrophobic than the others. However, the equilibrium moisture contents showed by the isotherms were not different for all types of plasticizers, in the same water activity. The equilibrium moisture data obtained for 5, 15, 25, 35 and 45 °C were adjusted by different mat... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Tecnologia de alimentos, Biofilme, Materiais biomédicos
Como citar
ALMEIDA, Crislene Barbosa de. Características estruturais e funcionais de biofilmes produzidos com zeína e óleos vegetais comestíveis. 2010. 91 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, 2010.