| Along with the development of bio-degradable packaging materials in recent years,more researches were conducted on the application of edible film.Antibacterial edible packing has become an important modern active packaging technology,with the ability of inhibiting the growth of various microorganisms in food or on packaging film,extending the shelf life of the products,and providing consumers with relatively safe products. Therefore,the development of the composite films with functions of antibacterial and food protecting, has become a research hotspot. Antibacterial efficiency of composite films those were made from whey protein,with the supplementation of natural antibacterial agents,was compared in this study. The combination of the antibacterial agents and processing of composite film were then screened. Thereafter,focusing on the weakness of whey protein based composite film on barrier properties and mechanical properties,effects of fortifiers on the pHysical properties of composite films were studied in order to develop one kind of composite film with better antibacterial property and fortified pHysical property,which could be used for food package.The results were as follow.1. Natamycin (100-300 mg/L) did not show restraining on the growth of bacillus subtilis,e. coli,salmonella,stapHylococcus aureus,and cheese lactobacillus. Whereas,the growth of red yeast jinggangmeisu,aspergillus,and trichoderma viride had been restrained by natamycin at the minimum concentration of 250 mg/L.2. The Poly-lysine showed better restraining on the growth of bacteria and yeast,but did not restrain the growth of trichoderma viride and aspergillus on lower concentration (100-500mg/Lmg/L). The minimum effective concentration of Poly-lysine was 100 mg/L on salmonella,and e. coli,whereas 400 mg/L needed on cheese lactobacillus and red yeast jinggangmeisu.3. The composite films supplemented with Natamycin (200mg/L) showed enhanced antibacterial property on trichoderma viride and aspergillus. The composite films supplemented with Poly-lysine showed enhanced antibacterial property on bacteria and yeast. The growth of the most of bacteria and yeast were restrained on the poly-lysine concentration of 400 mg/L. All of the bacteria,yeast and mold were restrained by the composite film with the combination of Natamycin and poly-lysine (250/400 mg/L).4. The physical properties of film were not greatly affected by the supplementation of natamycin and poly-lysine. The tensile and stab strength of films with the supplementation of natamycin reduced a little bit. The supplementation of polu-lysine resulted in the decreasing of film tensile strength and increasing of film stab strength. The combination of natamycin and poly-lysine resulted in the increasing of film thickness and stab strength,decreasing of film tensile strength.5. The tensile and stab strength of composite films supplemented with ferulic acid were increased significantly (p<0.05). But,the film pHysical properties got worse when supplementation was over 100 mg/L. The moisture content and solubility of films increased with the supplementation of lush mildew polysaccharides; The pHysical strength of films were enhanced with the supplementation of cysteine and ascorbic acid,The optimal combination of fortifiers was screened asferulic acid 100mg/L,lush mildew polysaccharides 2g/L,cysteine 0.025%,ascorbic acid 0.1%,using the orthogonal experiment design with film tensile and stab strength as main parameter. |
