赤霉素复合壳聚糖处理对火龙果采后品质及抗氧化能力的影响

Effect of Gibberellin Composite Chitosan Treatment on the Postharvest Quality and Antioxidant Capacity of Pitaya

火龙果营养丰富,深受消费者喜爱,然而火龙果采后贮藏期间易出现鳞片黄化、失水皱缩、腐烂变质等品质劣变问题,严重影响其商品价值。本研究为了探究赤霉素复合壳聚糖处理对火龙果采后品质及抗氧化能力的影响,以金都一号火龙果为试验材料,随机挑选大小均匀、成熟度一致,完好无损的火龙果分别设置6种处理:清水处理(对照)、5 g/L壳聚糖处理、50 mg/L赤霉素处理、25 mg/L赤霉素+5 g/L壳聚糖处理、50 mg/L赤霉素+5 g/L壳聚糖处理、100 mg/L赤霉素+5 g/L壳聚糖处理,处理后在25℃下恒温贮藏,定期测定火龙果的采后品质指标、脂氧合酶(LOX)活性、丙二醛(MDA)含量、抗氧化物质含量、抗氧化酶活性。结果表明:50mg/L赤霉素+5g/L壳聚糖处理的火龙果能较好维持火龙果的贮藏品质,在贮藏12d后,鳞片黄化率和失水率分别比对照降低15.91%和20.75%,果实可溶糖含量、颜色a*值和L*值均显著高于其余试验组,可溶性果胶含量显著低于其余试验组;50mg/L赤霉素+5g/L壳聚糖处理还能维持火龙果较强的抗氧化能力,贮藏12d后,果实丙二醛含量和脂氧合酶活性分别比对照降低16.04%和19.23%,抗氧化物质类黄酮、总酚、还原型谷胱甘肽(GSH)和还原型抗坏血酸(AsA)含量分别比对照提高10.07%、10.00%、31.43%和12.93%,抗氧化酶超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性分别比对照提高17.61%、79.22%和15.00%。可见,适宜浓度的赤霉素复合壳聚糖处理可有效维持火龙果采后品质,增强果实抗氧化能力,减轻膜脂过氧化损伤,延缓火龙果成熟衰老,延长保鲜期,复合处理可作为一种绿色环保、经济有效的保鲜手段,为火龙果采后贮运保鲜提供参考。

Pitaya contains abundant nutrients and is highly preferred by consumers.However,this fruit is prone to quality deterioration problems such as yellowing of fruit scales,fruit dehydration,peel shrinkage and decay during the postharvest storage period,which seriously affect its commercial value.Jindu No.1 variety was used to investigate the effect of gibberellin composite chitosan treatment on the postharvest quality and antioxidant capacity of pitaya.Pitayas of uniform size,consistent maturity and intact condition were randomly selected for six types of treatments:water(control group),5 g/L chitosan,50 mg/L gibberellin,25 mg/L gibberellin+5 g/L chitosan,50 mg/L gibberellin+5 g/L chitosan,and 100 mg/L gibberellin+5 g/L chitosan treatments.The pitayas were stored at a constant temperature of 25℃after treatment,and postharvest quality indicators including lipoxygenase activity(LOX),malondialdehyde(MDA)content,antioxidant substance content and antioxidant enzyme activity were measured regularly.The results showed the well-maintained storage quality of pitayas treated with 50 mg/L gibberellin+5 g/L chitosan.After 12 days of storage,the rate of fruit scale yellowing and water loss was reduced by 15.91%and 20.75%respectively compared with those of the control.The soluble sugar content,color a value and L value of the fruit were substantially higher than those of the other groups and the soluble pectin content was considerably lower than those in the other groups.The 50 mg/L gibberellin+5 g/L chitosan treatment could also maintain the improved antioxidant capacity of pitaya.After 12 days of storage,MDA content and LOX activity in the fruit decreased by 16.04%and 19.23%respectively compared with the control.The content of antioxidant substances such as flavonoids,total phenols,reduced glutathione(GSH)and reduced ascorbic acid(AsA)increased by 10.07%,10.00%,31.43%and 12.93%,respectively.The activity of antioxidant enzymes such as superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)increased by 17.61%,79.22%and 15.00%respectively compared with those of the control.The gibberellin composite chitosan treatment with appropriate concentrations could effectively maintain the postharvest quality of pitaya,increase the fruit’s antioxidant capacity,reduce membrane damage caused by lipid peroxidation,delay the ripening and aging of pitaya,and extend the preservation period.In addition,composite treatments could be considered a green,environmentally friendly,economical and effective preservation method that can serve as an application reference for pitaya storage,transportation and preservation industry after harvest.