外源甜菜碱与褪黑素复合处理对龙眼果实贮藏性能的影响

目的 研究不同浓度甜菜碱与褪黑素复合处理对采后龙眼果实冷藏的保鲜效果，以期为龙眼贮藏保鲜新技术提供理论参考。方法 以‘储良’龙眼为实验材料，分别采用0、5、10、15 mmol/L的甜菜碱与300 mmol/L的褪黑素复配制成保鲜剂处理果实。在温度为4 ℃、相对湿度为85%条件下贮藏，研究其冷藏期间质量损失率及可溶性固形物(TSS)、可滴定酸(TA)、抗坏血酸(VC)、丙二醛(MDA)、游离脯氨酸含量和过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性的变化。结果 与300 mmol/L褪黑素对照组相比，复合保鲜剂能有效减少龙眼果实水分、TSS、TA、VC和游离脯氨酸含量的损失，使龙眼果肉保持较高的SOD、CAT活性(P<0.05)，而POD活性和MDA含量维持在较低水平。结论 300 mmol/L褪黑素+10 mmol/L甜菜碱处理对龙眼的冷藏保鲜效果最佳。

Effects of Exogenous Betaine and Melatonin on Storage Performance of Longan

The work aims to study the effect of different concentrations of betaine and melatonin on the preservation of postharvest longan (Dimocarpus longan) fruits during cold storage, so as to provide theoretical reference of the new preservation technology of longan fruits. The ''Chuliang'' longan fresh fruits were treated with 0, 5, 10 and 15 mmol/L betaine combined with 300 mmol/L melatonin respectively, and stored at 4 ℃ and 85% relative humidity. The changes of the weight loss rate, soluble solids (TSS), titratable acid (TA), ascorbic acid (VC), free proline, malondialdehyde (MDA), and activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) were investigated. Compared with the 300 mmol/L melatonin control group, the composite preservative could reduce the loss of water, TSS, TA and VC. Meanwhile, betaine combined with melatonin manifested higher SOD and CAT activities (P < 0.05), and maintained lower levels of the MDA content and POD activity. Among them, the 300 mmol/L melatonin with 10 mmol/L betaine has the best preservation effect on longan fruits.