茉莉酸甲酯处理对采后‘黄冠’梨低温贮藏下果皮褐变及抗氧化能力的影响

通过分析茉莉酸甲酯(methyl jasmonate,MeJA)处理对‘黄冠’梨果皮褐变及部分生理指标的影响,探讨MeJA抑制‘黄冠’梨果皮褐变的机制。分别用1、10、100 μmol/L的MeJA水溶液浸泡处理‘黄冠’梨,经商品化包装后低温贮藏,观测贮藏期间果皮褐变情况,总酚含量和多酚氧化酶(PPO)、L-苯丙氨酸解氨酶(PAL)活性,过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)等抗氧化保护酶的活性以及自由基清除能力(DPPH)和过氧化氢(H₂O₂)含量等的变化。结果表明,100 μmol/L的MeJA处理,显著降低了‘黄冠’梨果皮褐变率及褐变指数,降低了PPO、PAL酶活以及总酚含量,提高了POD、CAT、APX等保护酶活性以及DPPH总抗氧化能力,降低了H₂O ₂含量。采后MeJA处理,通过降低果皮H₂O₂的积累、增强梨果皮抗氧化酶活性以及抑制PPO酶活和酚类物质的消耗,显著抑制了低温贮藏下‘黄冠’梨果皮褐变的发生。

Effects of MeJA Treatment on Skin Browning and Antioxidant Capacity of Postharvest ‘Huangguan’ Pear During Cold Storage

To study the inhibiting mechanism of MeJA on skin browning, treatment of 1, 10 and 100 μmol/L MeJA dip were applied to post-harvested ‘Huangguan’ pear fruits and the effects on skin browning spot index, polyphenol content, PPO and PAL activity, antioxidant defense systems including POD, CAT, APX activity, DPPH clearance ratio and the H₂O₂ content were detected. The results showed that compared with control (without MeJA treatment), treatment of 100 μmol/L MeJA reduced the skin browning spot index markedly, decreased PPO, PAL activity and polyphenol content, increased POD, CAT, APX activity and DPPH clearance ratio, decreased the H₂O₂ content. Above all, treatment of 100 μmol/L MeJA could reduce skin browning of ‘Huangguan’ pear during the long-term cold storage through inducing antioxidant defense of pear skin, removing H₂O₂ and inhibiting oxidation of phenols.