Study On The Technology Of Extrusion Casting Starch-based Edible Films

With preservation of food quality and continuous improvement of the requirements, as well as increased awareness of environmental protection, natural biological materials made of edible films in food packaging become a hot research field. The traditional solution cast film prepared edible packaging could not satisfy the needs of industrial production, due to the lower production efficiency. In this article, the thermoplastic starch was prepared by the method of melt mixture extrusion, and then prepared by extrusion casting edible starch-based packaging materials. The main results were as follows:1. The suitable film substrate was the oxidative esterification of starch and the suitable adhesive was the pullulan.2. The mobility of the thermoplastic starch was improved effectively by adding glycerol. With the addition of glycerol increased, the water dissolution time and tensile strength gradually decreased, while the elongation/ oxygen transmission rate/ transmittance/ water vapor permeability gradually increased. When the glycerol content<31%, the film was brittle and its tensile properties was poor; when the glycerol content>31%, the film was softer and its tensile strength was lower. The conclusion was: for the best properties of the starch film, the suitable addition amount of glycerol was 31%.3. The tensile strength of the starch film was improved effectively by adding pullulan. With the addition of pullulan increased, the water dissolution time and oxygen permeability gradually decreased. Lower water vapor permeability, higher whiteness value and lower yellowness value were obtained with the addition of pollution in the range of 5%～9%. The optical microscopy analysis of the film surface suggested that the pullulan and the starch can be fused better by the addition of pullulan with 9%.The conclusion was: for the best properties of the starch film, the addition of pullulan was better with no more than 9%.4. The mobility of the thermoplastic starch and the water resistance of the films were improved effectively by adding stearic acid. With the addition of stearic acid increased, the water dissolution time and tensile strength gradually increased, while the elongation and water vapor permeability gradually decreased. When the stearic acid content>1.6%, the fragility of the starch film gradually increased, the L color values decreased and the b color values increased. The conclusion was: for the best properties of the starch film, the addition of stearic acid was better with no more than 1.6%.5. The application of films results showed that: the starch film got better packaging properties, degradation properties and oxygen barrier properties. It could be used in oxygen-sensitive food packaging.