高分子量壳聚糖及其混剂对货架期葡萄的保鲜效果

Preservation Effects of High Molecular Weight Chitosan and the Mixture on Grapes during Shelf-Life

以新鲜巨峰葡萄为试材,分析了浓度为10 g/L的4种高分子量壳聚糖(相对分子量50、150、250、500 kDa)及其等比例混剂涂膜处理对货架期葡萄的保鲜效果。结果表明:5种壳聚糖涂膜处理在感官指标、可溶性固形物含量、VC含量、呼吸强度、可滴定酸含量、花青素含量等方面均不同程度地有利于葡萄的保鲜,其中4种高分子量壳聚糖等比例混剂涂膜的效果最佳;货架期第9天与第1天相比,5种壳聚糖涂膜处理的可溶性固形物含量下降率为19.7%~31.6%,对照为38.2%,混剂处理组的下降率与其他试验组存在极显著差异(P<0.01);呼吸强度下降率为58%~85%,对照为30%,混剂处理组与其他试验组存在极显著差异(P<0.01);VC含量下降率为38.5%~65.5%,对照为71.9%,混剂处理组与对照组存在显著差异(P<0.05);由上可知,4种高分子量壳聚糖等比例混剂涂膜处理可显著延缓葡萄衰老和品质的下降,对巨峰葡萄的保鲜效果明显优于单一壳聚糖涂膜处理的保鲜效果。

In this study, the fresh Kyoho grapes were used as test materials, and the preservation effects of four chitosan(50, 150, 250, 500 kDa) with a concentration of 10 g/L and the mixture on grapes during shelf life were analyzed. Results showed that all treatments could be benefit to the grapes preservation in varying degrees on sensory index, soluble solid content, VC content, absorption strength, titratable acid content and anthocyanin content.Among them, the coating film treatment mixed by 4 kinds of high molecular weight chitosan with equal proportion presented the best penetration effects. Compared with the first day, the soluble solid contents of treatment groups was decreased by 19.7% to 31.6% on the ninth day of shelf life(control group of 38.2%), and there was a highly significant difference(P<0.01) between the mixture and other experimental groups. The decrease rates of respiration intensity were 58% to 85% in treatment groups(control group of 30%), and there was a highly significant difference between highly significant difference(P<0.01) between the mixture and other experimental groups. The decrease rates of VC contents in treatment groups were 38.5% to 65.5%(control group of 71.9%), and there was a significant difference between(P<0.05) between the mixture and control groups. Therefore, the coating film treatment mixed by 4 kinds of high molecular weight chitosan with equal proportion could effectively delay the senescence of grapes and decrease of grapes qualities, and the preservation effect on Kyoho grapes was better than that of individual chitosan coating film treatment.