Combination Of Nisin And ?-Polylysine With Chitosan Coating On White Brush Of Fresh-cut Carrots

With the accelerating space of life,fresh-cut friuts and vegetables industry has attached more and more peoples' favor.The majority of consumers are fond of fresh-cut carrots,because its are rich in VC,carotenoids and other nutrients.However,during the storage,it is prone to dehydration,decay,white brush and other issues,lead to lose commercial value.In the present study,the concentration of nisin,?-polylysine and chitosan were optimized by preliminary experiments.We analyzed the sensory analysis,physico-chemical,microbical and the synthesis of enzyme activity of lignin and gene expression characteristics.The conclusions are as follows:1.We through determined the Physico-chemical of fresh-cut carrots,which found that all the three treatments: 1% lactic acid,1% chitosan coating,1% chitosan with nisin and?-polylysine coating could inhibit the weight loss,respiration rate and whiteness of fresh-cut carrots and,it also could inhibit the degradation of VC and the synthesis of lignin,cellulose and total phenol.however,1% chitosan with nisin and ?-polylysine coating has the best preservation of fresh-cut carrots' physical chemical.2.We through measured of microbial of fresh-cut carrots,found that all the three treatments of 1% lactic acid,1% chitosan coating,1% chitosan with nisin and ?-polylysine coating could inhibit the surface microbiological growth and reproduction of fresh-cut carrots.However,1% chitosan with nisin and ?-polylysine coating has the highest inhibited power.And on the whole storage,all the microorganism is in the safe range.Especially effect on staphylococcus aureus,we don't determine the staphylococcus aureus during the whole storage.3.We through determined the enzyme activity of fresh-cut carrots,which found that all the three treatments of 1% lactic acid,1% chitosan coating,1% chitosan with nisin and?-polylysine coating could improve the activity of PAL and PPO,meanwhile,its could inhibit the activity of POD,4CL and C4 H.However,the combined treatment has the significant effect.4.We through measured the gene expression of fresh-cut carrots,we found that all the three treatments of 1% lactic acid and nisian coating,1% chitosan and ?-polylysine coating,1% chitosan with nisin and ?-polylysine coating could improve the gene expression of DcPAL1,DcPAL3 and DcPAL4,and inhibited the Dc4 CL and DcC4 H.However,the combined treatment has the significant effect.These findings suggested that the combined application of nisin and ?-PL with chitosan coating might be the best alternative in maintaining preservative quality of the fresh-cut carrots during storage.