摘要：

为探究褪黑素在维持采后梨果实品质方面的潜力,为采后梨贮藏保鲜技术研发提供参考,以成熟期采收的新梨7号梨果实为试材,分别用0(对照),0.02,0.20,1.00 mmol/L的褪黑素溶液浸泡2,4,8,12,24 h后取样,测定了各处理对采后梨果实内在品质、细胞壁裂解相关酶活性、抗氧化相关酶活性及果皮与果肉内源褪黑素和水杨酸含量的影响。结果表明,用0.02,0.20,1.00 mmol/L褪黑素浸泡梨果实8 h,梨果实的硬度分别为38.51,42.79,40.95 N/cm²,乙烯释放速率分别比对照下降了66%,70%,71%;用0.20 mmol/L褪黑素浸泡梨果实8 h,果实的可溶性固形物含量(SSC)为94 g/L,显著高于对照组(80.2 g/L),为对照组的1.17倍,果实的可滴定酸(TAC)为1.013 g/L,也显著高于对照组(0.90 g/L),为对照组的1.13倍;此外,外源褪黑素处理显著提高了采后梨果实超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性,显著降低了采后梨果实多聚半乳糖醛酸酶(PG)、果胶甲酯酶(PME)、脂氧合酶(LOX)酶活性,同时提高了果皮内源褪黑素和果实内源水杨酸含量。综上,用0.20 mmol/L褪黑素溶液浸泡处理梨果实8 h,梨果实品质较好、细胞壁裂解相关酶活性较低、抗氧化酶活性较高、果实内源褪黑素和水杨酸含量较高,维持采后梨果实品质的潜力最大。

关键词: 梨, 果实品质, 酶活性, 褪黑素, 保鲜潜力

Abstract:

In order to explore the potential of melatonin to maintain the fruit quality of postharvest pear fruits,providing references for the research and development of storage and fresh preservation technologies of postharvest fruits,we carried out this research.In which Xinli No.7 pear fruits harvested at mature stage were selected as materials,and they were soaked in 0(control),0.02,0.20 and 1.00 mmol/L melatonin solutions for 2,4,8,12 and 24 h,respectively.Then we sampled and determined the effects of melatonin treatments on the internal qualities of pear,the activities of cell wall lysis related enzymes,the activities of antioxidant related enzymes,and the content of endogenous melatonin and salicylic acid in fruit peel and sarcocarp.The results showed that the hardness of the pear fruits soaked with 0.02,0.20 and 1.00 mmol/L melatonin for 8 h was 38.51,42.79,and 40.95 N/cm²,respectively,and the ethylene release rate decreased by 66%,70% and 71% respectively compared with the control.The soluble solid content(SSC)of pear fruits soaked with 0.2 mmol/L melatonin for 8 h was 94 g/L,which was significantly higher than that of the control(80.2 g/L)and was 1.17 times of the control.And the titrable acid(TAC)of pears of the same treatment was 1.013 g/L,which was also significantly higher than that of the control(0.90 g/L)and was 1.13 times of the control.In addition,treating pear fruits with exogenous melatonin could significantly increase the enzyme activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT),reduce the enzyme activities of polygalacturonase(PG),pectin methylesterase(PME)and Lipoxygenase(LOX),and could increase the endogenous melatonin content in fruit peel and the endogenous salicylic acid content in fruit(peel and sarcocarp).To sum up,soaking pear fruits with 0.2 mmol/L melatonin solution for 8 h had the maximum potential to maintain the fruit quality of postharvest pears,which could keep better fruit quality,keep lower cell wall lysis related enzyme activities and higher antioxidant enzyme activities,and could make the pear fruits having higher level of endogenous melatonin and salicylic acid content.

Key words: Pear, Fruit quality, Enzyme activity, Melatonin, Preservation potential