采前涂膜处理对宣化牛奶葡萄贮藏生理及品质的影响

研究采前涂膜处理对宣化牛奶葡萄的采后贮藏生理及保鲜效果。经采前挂蔓涂膜处理的牛奶葡萄在0℃条件贮藏100d，贮藏期间测定了果实的呼吸强度、乙烯释放量、总酚含量、叶绿素含量、可滴定酸含量等生理和品质指标。结果表明：采前涂膜处理可以显著抑制宣化牛奶葡萄果实在贮藏过程中的呼吸强度，处理组果实的呼吸强度比对照低42.5%～53.8%、并在一定程度上减少果实的乙烯释放量；采前涂膜能有效控制葡萄腐烂，贮藏结束时(100d)对照组腐烂率达75.3%，而涂膜处理组的腐烂率只有5.2%。同时可以减少褐变，贮藏75d时处理组的褐变指数比对照低81.6%。保持果实鲜绿色，处理组果实果皮叶绿素含量在50d和75d时为0.04mg/g和0.33mg/g，而对照组则为0.02mg/g和0.015mg/g；也可以保持葡萄果实可溶性固形物、可滴定酸含量，保持感官品质，延长保鲜期约50d。

Effect of Preharvest Coating Treatment on Physiology and Quality of Grape during Storage

In this study, xuanhua-milk,, grapes were soaked in chitosan coating solution before harvest, and stored at 0 ℃ for 100 d. The respiration intensity, ethylene production, total phenolics content, polyphenol oxidase activity, chlorophyll content, titratable acidity, soluble solids content, weight loss, decay rate and browning index of the grapes were investigated during storage. The results showed that the coating treatment had good effect on inhibiting the respiration intensity, ethylene production and polyphenol oxidase activity. Compared with untreated grape, respiration intensity of grape treated with preharvest-coating were reduced by 42.5% at 50 day and 53.8% at 75 day, respectively. After storage for 100 days, decay rate was 5.2% in coating-treated group, and 92% in the control group. Browning index was reduced by 81.6% at 75 day compared with untreated grape. Meanwhile, higher soluble solids, titratable acid, chlorophyll and total phenolics content remained in grapes of coating-treated group than in the control. Furthermore, preharvest coating increased the shelf life and maintained the sensory quality of grape fruits, resulting in a 2-fold prolongation of shelf-life compared with untreated grape.