采后褪黑素处理对余甘子果实品质和耐贮性的影响

余甘子（Phyllanthus emblica L.）是联合国卫生组织指定的全世界推广种植的3种保健植物之一,在中国也被列为药食两用的水果,具有营养丰富,保健价值突出的特点。然而采后余甘子果实易发生失水皱缩、腐烂变质等问题,极大地影响了其商品价值。褪黑素（melatonin）是一种小分子吲哚胺类物质,在动植物体内广泛存在,其在植物中可有效清除自由基,在植物的抗逆抗病中也具有重要的调控作用。采用适宜浓度的褪黑素处理果蔬可以起到较好的保鲜作用,有效延缓果蔬腐败变质,提高采后耐贮性。为提高余甘子果实采收后的耐贮性,以‘蓝丰’余甘子果实为试材,探究采后褪黑素处理对于常温下贮藏的余甘子果实品质和耐贮性的影响。将挑选出的无机械损伤及病虫害,大小和色泽相近的余甘子果实,随机平均分为2组,处理组余甘子用0.3 mmol/L褪黑素溶液浸泡处理20 min,空白对照组则用去离子水浸泡20 min,取出晾干1 h后用聚乙烯薄膜袋包装,而后置于温度为(25±1)℃、在相对湿度85%~90%的恒温箱中贮藏,每3 d取样测定果实的商品率、感病指数、呼吸强度等品质和耐贮性相关指标。试验结果表明,采后褪黑素处理使余甘子果实在贮藏末期的商品率提高22%,显著降低了余甘子果实的感病指数、呼吸速率和失重率;且经褪黑素处理的余甘子果实可溶性固形物、可滴定酸度和维生素C的含量均高于对照组,余甘子表皮颜色和果肉质地的劣化也比对照缓慢。褪黑素处理有利于延缓采后余甘子病害的发生和提高果实品质及耐贮性。本研究为褪黑素在余甘子果实采后贮藏保鲜应用提供理论依据,丰富了褪黑素应用于果蔬保鲜的理论基础。

Effects of Postharvest Melatonin Treatment on Fruit Quality and Storability of Phyllanthus emblica Fruit

Phyllanthus emblica L. is one of the three health plants designated by the World Health Organization to be cultivated worldwide. In China, P. emblica has also been listed as a kind of fruit that can be used as medicine and food, with rich nutrition and outstanding health care value. However, harvested P. emblica is prone to suffer problems such as water loss, shrinkage, decay and deterioration, which greatly affects the commercial value of P. emblica. Melatonin is a ubiquitous bioactive molecule with diverse functions in plants and animals. Melatonin has an effective scavenging effect on free radicals in plants, and also plays an important regulatory role on plant resistance to diseases. Treating fruits and vegetables with appropriate concentration of melatonin is beneficial for the preservation, delaying fruit and vegetables spoilage effectively, and improving postharvest storability. In order to improve the storability of harvested P. emblica fruit stored at room temperature, the effects of melatonin treatment on the storability of ‘Lanfeng’ P. emblica fruit were investigated in this research. The selected P. emblica fruits without mechanical damage, diseases and insect damage, with similar size and color, were randomly divided into two groups. The two groups of fruits were respectively dipped in 0.3 mmol/L melatonin solution and deionized water (control) for 20 min. After the dipping treatment and dried for 1 h, the treated fruits were packed in low density polyethylene film bag and stored at room temperature (25±1)℃and 85%-90% relative humidity for 21 days. The marketable fruit commercial rate, disease index, respiratory intensity and other related indexes of fruit quality and storability were determined every three days. The results showed that the postharvest melatonin treatment increased the marketable fruit commercial rate of P. emblica by 22% at the end of storage, significantly reduced the disease index, respiration rate and weight loss of P. emblica fruit. In addition, the contents of total soluble solids, titratable acidity and vitamin C in melatonin treated P. emblica fruits were higher than those of the control fruits, and the deterioration of skin color and flesh texture was slower than that of the control fruits. In conclusion, melatonin treatment could delay the occurrence of postharvest diseases and improve the quality and storability of P. emblica fruits. The results of this research would provide a theoretical foundation for the application of melatonin in preservation of harvested P. emblica fruits, and enrich the theoretical basis on the application of melatonin in preservation of fruits and vegetables.