荔枝果实采后脂氧合酶活性的变化

Changes of Lipoxygenase Activity of Postharvest Litchi Fruit

研究了采后冷藏、外源ABA、亚精胺(Spd)、1-甲基环丙烯(1-MCP)、热处理及酸处理对荔枝果实脂氧合酶(LOX)活性变化的影响。荔枝果实组织中LOX活性测定反应系统的最适pH是6.5。与3℃冷藏相比, 0℃下糯米糍果皮LOX活性升高较快,丙二醛(MDA)含量积累加快,在21 d时分别高出34.9%和25.6%。0℃下桂味果皮LOX活性先升后降,于14 d达到高峰。冷害促进了果皮LOX活性增加,但0℃下糯米糍果肉的LOX活性和MDA含量均低于3℃下果肉。外源ABA、Spd、1-MCP处理不同程度地降低了果皮LOX活性,减轻了果实冷害的发生程度。推测由LOX主导的膜脂过氧化作用引起的膜结构破坏在荔枝果实衰老和冷害褐变中可能起重要作用。46.2-80.0℃的热水处理诱导LOX活性的升高,适当浓度的酸则显著抑制该酶的活性。

Effects of low-temperature storage, exogenous abscisic acid(ABA), spermidine(Spd) and l-methylcyclopropene(1-MCP), hot water dipping and acid dipping on lipoxygenase(LOX) activities of postharvest Litchi chinensis Sonn. ) were investigated. The suitable pH in the measurement system for litchi fruit was 6. 5. The fruit stored at 0℃@developed chilling injury . The LOX activity and malondial-dehyde(MDA) content in pericarp increased higher than that at 3 ℃. However, the LOX activity and MDA content in the pulp at 3 ℃ were higher than those at 0 ℃. Treatments with ABA, Spd or 1-MCP restrained the LOX activities of fruits at 0℃ during the 14th and 21st day and alleviated the chilling injury slightly. These results indicated that the membrane lipid peroxidation catalyzed by LOX may play an important role in the damage of the membrane structure and the browning of litchi pericarp. LOX activity of pericarp increased immediately after dipping in 46. 2-80 ℃ water , but significantly inhibited by proper acid dipping.