Studies On Mechanical And Application Of Edible Films From Rice Protein

In this paper, we prepared the edible films by rice protein extracts. The films were preparedwith thickness, mechanical properties, water vapor and oxygen permeability as index. Theeffects of preparation, content of plasticizer, enzyme polymerize and lipids on the film propertieswere investigated. At last, we did some research of the application of the film.The conditions of preparing the edible films were optimized as following: the content ofRPE: 5g/L;the addition level of glycerin: 3±0.5g/L;pH: 11±0.5;treatment temperature: 80±5℃;treatment time: 10～30min. The physical characteristics of the films were tested: elogationof 102.4±18.5%, tensile strength of 2.35±0.54MPa,water vapor permeability of 35.1±1.9g·mm/ kPa·d·m2 and oxygen permeability of 2.8±0.3 cm3·ηm/m2·d·kPa.Transglutaminase introduced covalent crosslinkage of ε-(γ-glutamyl)-lys between riceproteins, can enhance the films framework and compactness, increase films tensile strength anddecrease water vapor permeability. The result indicated that the tensile strength enhanced by43.9%, water vapor permeability decreased 19.6% without visible change of elongation andoxygen permeability. Scanning electron microscopy was used to investigate the microstructure ofthe films. The results indicated that the uniform and compact of films was enhanced by TG.Various lipids were added into the solution due to RPE films have quite high water vaporpermibility. The presence of stearic acid, sucrose fatty acid ester and bee wax increased the watervapor barrier. And the films contain stearic acid, sucrose fatty acid ester perform better than beewax. The surface and side views indicated that stearic acid and sucrose fatty acid ester caninteract with rice protein, they have little effects on mechanical properties.Almond and peanut kernel were coated with RPE edible films which has low oxygenpermeability. Stored at 40℃ for 40 days, the acid value decreased for 25.8% and 51.2%,peroxide values decreased for 25.1% and 45.3% compared to uncoated samples. So RPE ediblefilms can effectively delay the oil of nuts hydrolyzation and oxidation, extend the shelf life.