目的:研究气调贮藏对桃果冷害的防控效果及可能机制.方法:以'锦绣'黄桃为材料,研究体积分数5%O2+10%CO2对桃果实低温((0+2)℃)贮藏和货架(20 ℃、3d)期间褐变指数、硬度、乙烯释放速率、活性氧(reactive oxygen species,ROS)含量、丙二醛含量、抗坏血酸-谷胱甘肽(ascorbic acid-glutathione,AsA-GSH)循环相关物质含量及关键酶活力、挥发性物质含量的影响,结果表明:与对照组相比,气调贮藏可减缓桃果冷害症状,贮藏30 d后再货架3 d(30dS3样品),褐变指数低于10%,果实硬度降低至10 N以下,乙烯释放速率为对照组的1.7倍.在低温贮藏后期,气调贮藏果实中总ROS、丙二醛和过氧化氢含量显著低于对照组(P<0.05、P<0.01),1,1-二苯基-2-三硝基苯肼自由基和2,2'-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基清除能力显著高于对照组(P<0.05、P<0.01),超氧化物歧化酶(superoxide dismutase,SOD)活力在30dS3样品中提高36%,AsA-GSH循环中的抗坏血酸过氧化物酶、脱氢抗坏血酸还原酶、谷胱甘肽还原酶和单脱氢抗坏血酸还原酶活力整体提高,有效抑制还原型抗坏血酸向脱氢抗坏血酸的转化.此外,与对照组相比,在货架结束时,气调贮藏组积累了更多C6醇、酯类、内酯类芳香物质,γ-癸内酯、γ-十一内酯和δ-癸内酯含量在30dS3样品中分别提高了2.0、1.6倍和4.0倍,同时积累更多蔗糖和山梨醇以及更少的葡萄糖和果糖.结论:5%O2+10%CO2处理通过激活AsA-GSH循环和SOD活力,增强活性氧清除能力,缓解桃果冷害,维持香气品质.
In order to explore the effect of controlled atmosphere(CA)storage on alleviating chilling injury(CI)in peach fruit and the possible underlying mechanism,the effect of CA treatment(5%O2+10%CO2)on internal browning index(IB),firmness,ethylene release rate,reactive oxygen species(ROS)content,malondialdehyde(MDA)content,compounds and key enzyme activities related to the ascorbic acid-glutathione(AsA-GSH)cycle and volatile contents in yellow-fleshed peach fruit(cv.Jinxiu)during low temperature((0±2)℃)storage and shelf(20 ℃,3 d)was investigated.The results showed that CA alleviated CI significantly relative to the control group;on the third day of the shelf life after 30-day cold storage(30dS3),IB was lower than 10%,fruit firmness decreased to below 10 N,and ethylene release rate was 1.7-fold as high as in the control.During the late period of cold storage,the contents of total ROS,MDA,and hydrogen peroxide(H2O2)were significantly lower and scavenging capacities against 1,1-diphenyl-lpicrylhydrazyl(DPPH)and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)radical cation free radicals were significantly higher in the CA-treated fruit than the control group(P<0.05 or P<0.01).Meanwhile,in the CA-treated peach fruit,the activity of superoxide dismutase(SOD)was increased by 36%on 30dS3,while the activities of AsA-GSH cycle-related key enzymes such as ascorbate peroxidase(APX),dehydroascorbate reductase(DHAR),glutathione reductase(GR)and monodehydroascorbate reductase(MDHAR)were enhanced,and the conversion of reduced ascorbic acid to dehydroascorbic acid was significantly inhibited.Moreover,CA treatment accumulated higher amounts of C6 alcohols,esters,and lactones compared with the control group at the end of the shelf life;on 30dS3,the contents of γ-hexalactone,y-decalactone,and δ-decalactone were increased by 3.0,2.6 and 5.0 folds compared with the control group,respectively.In addition,higher contents of sucrose and sorbitol and lower contents of glucose and fructose were observed in the CA-treated fruit.Therefore,CA treatment(5%O2+10%CO2)can alleviate CI and maintain aroma quality by activating the AsA-GSH cycle and SOD,and enhancing ROS scavenging capacity in peach fruit.