| Currently, the white pollution, exhaustion of mineral resources, and other problemscaused by plastic packaging material make the research focus on the environment friendly andbio-degradable packaging films. In this paper, zein was used as raw material to prepare zeinfilms at different processing conditions, and plasticizer and cross-linking agent was added toimprove the mechanical and barrier property. The aim is to extand the application of zeinfilms.In single factor experiments, effects of ethanol concentration, the ratio of glycerol,polyethylene glycol (PEG-400) and monoglycerides to zein on the mechanical properties,moisture content, water soluble property and barrier property of the film were discussed. Thesuitable preparing conditions initially determined were: ethanol concentration80%(v/v),glycerol/zein ratio0.3(g/g), PEG/zein ratio0.2(g/g) and monoglycerides/zein ratio0.3(g/g).Based on the single factor experiments, the tensile strength, breaking elongation, watervapor permeability was hired as the evaluation indexes to optimize the preparing conditions ofzein films by Respone Surface Methodology(RSM). The optimized conditions were: ethanolconcentration80.86%(v/v), glycerol/zein ratio0.29(g/g), PEG/zein ratio0.16(g/g), andmonoglycerides/zein ratio0.30(g/g). The zein film indexes prepared at these conditions were:tensile strength (TS)4.19MPa, elongation (E)237.00%, water vapor permeability1.44×10-4gmm/m2hKPa. Compared to single factor experimental results, the tensile strength andwater vapor permeability increased, while the elongation decreased.The anti-digestion capability of zein film was researched at simulated gastrointestinalenvironment. The enzymatic degradation percentage was84.64%after keeping the film inpepsin solution for4hour then in trypsin solution for4hour. It can be concluded that zeinfilm prepared in the selected conditions is able to be used as edible films.Water buried soil nutrient solution method and natural method were used to degrade thezein film for22days, respectively. The weight loss was31.66%in water buried soil nutrientsolution and94.01%in natural conditions. Based on the weight loss in two methods, it can beconjectured that zein film can be degraded in natural conditions. It could meet the damands ofdegradable material. |
