| Edible films have received great interest in food preservation and been used widely. Interest and research activity in soy protein isolate (SPI) film have been especially intense all around the world. In this paper, the film-forming characteristics of SPI were systematically studied,the effect of blend-modification of lipids and polysaccharides on barrier and mechanical properties of composite film was examined, and finally, practical application of SPI edible film in coating of nuts was investigated.The result of single-factor experiments showed: binding film was optimal filming medium; the optimal film-forming SPI concentration was 5g/100mL, water bath temperature was 80℃, water bath time was 20min, glycerin concentration was SPI:GLY=2:1, film-forming solution pH was 9, drying temperature was 60℃during 6h .The optimal film-forming conditions were obtained through orthogonal experiment design:SPI concentration 4g/100mL, glycerin concentration ( SPI:GLY=2:1 ) ,the film-forming solution pH 11, the drying temperature 70℃during 6h.Blend-modification of SPI solutions with Polysaccharide has been used to form SPI/Polysaccharide edible films. With addition of Polysaccharide, Reduction in elongation (in addition to the soluble starch) and transparency of film could be achieved; Increase of tensile strength (in addition to sodium alginate), permeability of water vapour and oxygen of film could be achieved. Blend-modification of SPI solutions with monoglyceride and lauric acid to has been used to form SPI/lipid emulsion edible films. Significant reduction in permeability of water vapour and oxygen could be achieved upon addition of lauric acid and monoglyceride.Peanut Kernels and almond were coated with SPI edible films. Stored at 60℃for 10 day, the peroxide values decreased for 48% and 34.7%, acid value decreased for 44% and 40.5% compared to uncoated samples. So SPI edible films can effectively delay the oil of nuts hydrolyzation and oxidation, slowdown the deterioration, extends the shelf life.
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