| Chitosan film is a kind of high molecular polymer that can be completely degraded by biological means.It has certain mechanical properties and good barrier properties to various small molecules.It is a kind of green environment-friendly film packaging material with broad development prospect.?-polylysine,as a new natural preservative,has been widely used in Japan,the United States and other countries.its bacteriostatic effect is good,not only and security is also high.In addition,previous studies showed that adding ?-polylysine to chitosan could improve the bacteriostatic ability of chitosan,but the mechanical properties of the membrane remained to be improved.Sodium tripolyphosphate(TPP)is a polyphosphate formed by condensation of different sodium hydrogen phosphate molecules.Because of its ability to regulate p H,it is often used in washing and sewage treatment.Studies have shown that the phosphate in the TPP molecular structure can be connected to the amino site of chitosan,so that the two can form an ionic gel.Therefore,TPP can be combined with chitosan to improve the mechanical properties of chitosan membrane.In this study,TPP crosslinking ?-polylysine/chitosan composite films were prepared by flow,in which ?-polylysine concentration was 0%,1%,3% and 5%(compared with chitosan),and TPP content was 1%(compared with chitosan),respectively.To study the different ?-polylysine concentration and TPP on chitosan complex film pervious to light quality,mechanical properties,oxygen permeability and moisture permeability,the influence of antibacterial performance.The results showed that the addition of ?-polylysine improved the elongation at break and light transmittance of the composite film,and its bacteriostatic properties.At the same time,the addition of TPP could promote the crosslinking between ?-polylysine and chitosan in the composite film,and significantly improved the barrier properties and bacteriostatic properties of the composite film.In addition,in order to investigate the preservation performance of-polylysine/chitosan solution,fresh cut apples were coated with ?-polylysine/chitosan solution.The preservation performance of the composite film was investigated by testing the indexes of the experimental samples including fruit yield,weight loss,hardness,sensory scores,soluble solids and VC content.The results showed that,compared with the control group,the sensory scores of experimental samples coated with TPP ?-polylysine/chitosan were significantly improved,and the decrease of hardness,weight loss,soluble solids and VC content was effectively inhibited.?-polylysine/chitosan for fresh-cut apples was further improved.And add the TPP makes composite membrane further suppress the VC content in fresh cut apples fall. |
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