Research On Preparation Of Soy Protein Isolate-based Edible Film

Edible films are biodegradable, non-polluting packaging films which are prepared from renewable resources, such as proteins, polysaccharides, lipids or the combination of these components. Their application in food industry becomes perspective. Among them, edible films of proteins are most attractive.In order to improve the properties of soy protein isolate (SPI)-based edible film, the paper studied the effect of polysaccharides and cross-linking agents on the properties of SPI-based edible film. The experimental results showed that the addition of pectin into film forming solutions of SPI effectively increased mechanical strength and addition of glucose effectively decreased permeability of water vapor and oxygen. Furthermore, pectin and glucose had positive interaction effect on the properties of SPI-based edible film.Based on the experimental results mentioned above, an orthogonal experiment was used to test the effect of film forming temperature, the concentration of pectin and glucose on the properties of SPI-based film. The results showed that the optimal film forming temperature was 70 癈, the optimal concentration of pectin and glucose was 1% and 0.1%(W/V) respectively. Under these conditions, the tensile strength greatly increased while the permeability of water vapor and oxygen decreased significantly.The possible mechanism of pectin and glucose in improving mechanical properties was that they increased cross-linking between amino acids in and between protein molecules.