短波紫外线照射对‘金都’火龙果采后保鲜的影响

Effect of UV-C Irradiation on Preservation of Hylocereus polyrhizus‘Jindu’Fruits

以‘金都’火龙果(Hylocereus polyrhizus‘Jindu’)果实为试材,采用波长254 nm紫外杀菌灯为辐射源,给予不同剂量短波紫外线(Ultraviolet-C,UV-C)照射处理,探讨低剂量UV-C对火龙果采后保鲜的影响及作用机理。结果表明,不同剂量UV-C照射处理能有效抑制‘金都’火龙果果实腐烂和电导率上升,降低果实TSS含量,其中1.0 kJ·m(-2)紫外线辐照效果最好。1.0 kJ·m^(-2) UV-C处理能极显著提高贮藏期火龙果的SOD和CAT活性,显著提高贮藏早中期的几丁质酶活性和PPO活性,β-1,3葡聚糖酶活性在贮藏后期也显著高于对照,但降低了火龙果贮藏中期(第6天)的POD活性。此外,1.0 kJ·m^(-2) UV-C处理显著提高火龙果贮藏期H_(2)O_(2)含量(除第6天外),对果实的失水率无影响。采后火龙果应用适当剂量UV-C照射可提高抗病性,延长贮藏保鲜期。

Influences of low dose short wave ultraviolet(UV-C)on the preservation of dragon fruit and its action mechanisms were studied for providing scientific basis of UV-C application in dragon fruit storage.The test material was‘Jindu’dragon fruit and common ultraviolet germicidal lamp with wavelength of 254 nm was used as the radiation source.The dragon fruits were irradiated with the radiation dose of 0,1.0,2.0,3.0,1.0 kJ·m^(-2),respectively.Then we conducted the experiment that the optimal dose of UV-C was selected by measuring the decay rate,electrical conductivity and TSS content of the dragon fruit.Dragon fruits treated with optimal dose of UV-C were stored under the condition of 22±1℃.Water loss rate,H_(2)O_(2) content and defensive enzyme activity were measured periodically during storage.Different doses of UV-C treatment effectively inhibited the rot of dragon fruit and the increase in electrical conductivity,and reduced the TSS content in dragon fruit.1.0 kJ·m^(-2) UV-C treatment had the best effect with significantly increasing of SOD and CAT activities in dragon fruit during the whole storage period,and significantly improving to chitinase and PPO activities in the early and middle storage period.Theβ-1,3-glucanase activity in the late storage period was also significantly higher than that of the control.But it reduced the POD activity in the middle storage period(the 6th day).In addition,1.0 kJ·m^(-2) UV-C also significantly increased the H_(2)O_(2) content during storage(except for the 6th day),and had no effect on the water loss rate of the fruit.