Study On Preservation,characterization And Preparation Of Chitosan/Poly-lysine Composite Membrane

Chitosan is the product of chitin,which is widely found in the shell of shrimp,crab and insect,and the cell wall of algae and fungi.It is the second largest natural polymer which is second only to cellulose.Chitosan has been widely used in the field of fruit and vegetable preservation because of its non-toxic,non polluting and biodegradable.Poly-lysine is a kind of natural biological metabolic product,which has good bactericidal ability and thermal stability.At the same time,poly lysine can also be used in combination with other natural antibacterial agents,which has obvious synergistic effect,and can enhance the antibacterial ability.In this study,chitosan/poly-lysine composite membrane was prepared by casting method with different concentration of poly-lysine in chitosan solution,and the concentration of lysine was 0%,1%,3%,and 7%,respectively.The transmittance,mechanical properties,moisture permeability,oxygen permeability and antibacterial property of the composite film were characterized,and the morphology of the composite film was observed by scanning electron microscope(SEM).The results showed that the addition of lysine significantly improved the antibacterial activity of chitosan membrane and decreased the barrier to oxygen,but had no significant effect on the mechanical properties,water vapor permeability and light transmittance.In addition,the chitosan/poly-lysine were coated on citrus,through the determination of weightlessness on Citrus sensory score,rate,sugar content,Vc content,corruption rate index,the effects of chitosan/poly-lysine on citrus preservation.The results showed that the experimental group compared with control group,during storage of Citrus sensory score,sugar content and Vc content decreased slowly,weight loss rate and the corruption rate rises slowly,which indicates that the preservation of Citrus effects in the experimental group was better than control group.When the concentration of lysine was 1%,the weight loss rate and sugar content of citrus were the smallest,and the sugar content decreased at the maximum of 3%,and the sensory score was the slowest and the lowest rate was the lowest when the content was 7%.On the whole,when the concentration of lysine was 1%,chitosan/poly-lysine solution had the best fresh-keeping effect on citrus.