Preparation And Application Of Tea Polyphenol Incorporated Soy Protein Isolate Films

Preparing edible films with soy protein isolated (SPI) with good barrier and degradable properties is a hotspot both in domestic and foreign research. This paper investigated the properties of SPIfilms affected by componentmateria and ultrasonic treatment; creatively made SPI films which had antibacterial and antioxidant functions by adding tea polyphenol(TP); optimized the compose and conditions of SPI films'preparation in order to improve the moisture resistance and mechanical properities of the films.Apply the SPI films containing TP to preserve cherrytomatoes and grease, the result showed that this films had a stable properity, remarkable preservation effect on cherrytomatoes and prevent grease oxidation.This paper measured the films'water vapor permeability, tensile strength, breaking elongation to evaluate infaction of the mass concentration of SPI, Na2SO3, glycerol and ultrasonic time. The result showed that the influence of ultrasonic time was most obvious, the optimal time was 15min; the respective optimal mass concentration of SPI and Na2SO3 were 60g/L and lg/L; the glycerol's optimal mass concentration was 30g/L. Prepare SPI films which had antibacterial and antioxidant functions by adding TP with different concentrations. The films'moisture resistance, mechanical properity and antioxidant properities were improved greatly when the TP's concentration was 2g/L. The SPI films containing tea polyphenols showed smooth surface through scanning electron microscope. Moreover a L16 (44) orthogonal test was made with the factors of the mass concentration of SPI, Na2SO3, tea polyphenol and the ultrasonic time.The best film forming condition as follows:the mass concentration SPI was 50 g/L, Na2SO3 was 1 g/L, TP was 2 g/L and ultrasonic time was 15min.Lastly, Apply the SPI films containing TP to preserve cherrytomatoes and grease. Measured the cherrytomatoes'rotting index, weight loss, the content of Vc and titrate acid to evaluate the preservation effect, measured the peroxide value to estimate the antioxidative effect of different films. The result showed that after stored for 12 days in room temperature, the quality of film coated cherry tomatoes is better than the SPI films, the rotting index and weight loss rate were decreased, the content of Vc and titrate acid were high than the SPI films without TP, indicating the film has good preservation effect the films oxygen resistentance abilities were:SPI film containing TP>SPI film>LDPE> contrast, demonstrated the SPI film containing TPeffectively suppress grease oxidation.