The Preparation And Characterization Of ?-polylysine/PVA Composite Films And The Effect On Longan

Polyvinyl alcohol is a kind of completely biodegradable polymer,its molecular structure contains hydroxyl,it can dissolve in water,and the film made by them has a high degree of film-forming property and high barrier property,its mechanical property is also very excellent,which is a kind of environmental protection packaging materials with many advantages.Polylysine is a kind of light yellow powder,it has many advantages,such as wide antimicrobial spectrum,high safety,strong solubility in water and so on,which has been widely used in Japan?the United States?South Korea and other countries as a food additive.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,(?-PL/PVA)composite films with the concentration of polylysine of 0%,1%,3%,5%and 7% were produced by cast coating.The molecular interactions and microstructure of the films were analyzed by Fourier transform infrared spectroscopy and scanning election microscope,and the effect of the concentration of ?-PL on the light transmittance,mechanical properties,oxygen permeability and antibacterial of ?-PL/PVA films were studied.The results showed that ?-PL can improve the breaking elongation,light transmittance and antibacterial properties of PVA films.In addition,the ?-PL/PVA composite films were used to pack the longan.We investigate the fresh-keeping performance of ?-PL/PVA composite films on longan through the determination of rate of good fruit,weight loss,the browning index of peel,pulp autolysis,sugar content,VC content and titratable acid content.The results showed that all the index of experimental group were better than the unpacked group.Compared with the PE group,the ?-PL/PVA group had increased the rate of good fruit,the index of peel browning and the loss of VC content had been restrained,and had a good influence on the change of sugar content and titratable acid content.At the same time,with the improvement of ?-PL content,the rate of good fruit had been improved.After 25 days of storage,the rate of good fruit with 0% and 7% concentration of ?-PL was improved to 76.6% and 90% compared with the control.On the whole,?-PL can improve the packing and preservative of PVA film,we can predict that ?-PL/PVA composite films has the good application in food packaging.