ClO_2和1-MCP对青皮核桃二步贮藏的效应

Effect of ClO_2 and 1-MCP on Preservation of Green Fruit and Peeled Walnut in Two-step Storage

为了探究高效、无公害的核桃保鲜方法,以＂辽宁2号＂青皮核桃为试材,分别采用80 mg/L二氧化氯（Cl O2）和0.5μL/L 1-甲基环丙烯（1-MCP）处理,将青皮核桃（湿鲜坚果）二步贮藏于0-1℃,相对湿度70%-80%条件下,并以清水浸泡为对照。贮藏期间观测果实的保鲜效果、核仁抗氧化特征及品质的变化。结果表明：Cl O2处理延迟青皮果实腐烂6 d,延迟脱青皮坚果霉变5 d。第1步贮藏结束时（60 d）Cl O2、1-MCP和对照果实的腐烂指数分别为14.2%,20.1%,18.7%;第2步贮藏40 d,二步贮藏结束时（60＋40）d,三者坚果的霉变率分别为11.6%,30.3%,24.8%。种皮、核仁的总酚和类黄酮含量分别于（60＋20）d,（60＋30）d前上升,之后下降,Cl O2处理的峰值均显著高于其他处理（P〈0.05）。三者的核仁抗氧化活性与其总酚变化一致。Cl O2处理的核仁感官品质下降以及酸价、过氧化值、可溶性蛋白含量、丙二醛（MDA）含量和脂氧合酶（LOX）活性增加均显著慢于对照,而1-MCP处理的上述变化居中。Cl O2处理明显延缓了青皮核桃腐烂和湿鲜坚果霉变,保持了较高的核仁品质。1-MCP仅延缓了核仁品质下降。

To develop an efficient and pollution-free method for fresh walnut preservation, green walnut fruit of cv.Liaoning 2 was harvested and stored with two-step ways under 0~1 ℃, RH 70%~80%, which were treated by 80 mg/L Chlorine dioxide（Cl O2）, 0.5 μL/L1-methylacrylic（1-MCP）, and water（control）, respectively. During storage, preservation status of green walnut fruit and fresh walnut, changes of antioxidant activity and traits of kernel, were measured periodically. The results showed that Cl O2 delayed fruit＇s decaying and walnut＇s mildewing 6 d, 5 d, respectively. Decay index of fresh fruit reached 14.2%, 20.1%, 18.7%, respectively, for Cl O2, 1-MCP and control at the end of first-step storage（60 d）. Mildew rate of fresh walnut reached 11.6%, 30.3%, 24.8% at the end of second-step storage（60＋40） d.During second-step storage, content of total phenols, flavonoids of kernel and its skin generally raised during（60＋20） d,（60 ＋30） d, respectively, then descended, each peak value of walnut from Cl O2 treatment was greater than that from control and 1-MCP statistically（P 0.05）. Total antioxidant activity and changes of kernel from treatments and control showed the same trend as that of total phenols. Kernel from Cl O2 treatment presented slower decline in sensory quality,less increase in acid value, peroxide value, soluble protein content, malondialdehyde（MDA） content, lipoxygenase（LOX） activity than that from control. Those changes from 1-MCP treatment happened faster than Cl O2, whereas slower than control. In conclusion, Cl O2 significantly delayed decay of green walnut fruit and mould of fresh walnut, maintained better kernel traits. However, 1-MCP just delayed the decline of kernel traits.