仿生膜对轻度加工葡萄自由基和保护酶的影响

Effects of mimetic bio-membrane on free radical and protective enzymes of lightly processed grapes

以红地球葡萄为试验材料,研究壳聚糖仿生膜对轻度加工葡萄品质和超氧阴离子自由基(O2-.)、丙二醛(M DA)含量、电解质渗漏以及超氧化歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等保护酶活性动态变化的影响,探讨轻度加工果实组织衰老和与保护酶的关系,以及仿生膜在果实成熟衰老进程的作用。结果表明:与对照相比,1.5%的壳聚糖仿生膜能抑制SOD、POD、CAT活性下降,减低O2-.生成速率,进而抑制M DA的积累,维持细胞膜的稳定性,延缓果实成熟衰老进程。相关性分析表明,O2-.生成速率与SOD、CAT呈极显著负相关(r=-0.975**,-0.546**),与POD呈显著正相关(r=0.442*),说明保护酶对抑制O2-.产生具有重要作用。1.5%壳聚糖仿生膜可有效抑制保护酶活性降低和自由基的产生,1.2%和1.8%壳聚糖仿生膜没有明显的效果。

Effects of mimetic bio-membrane treatments on ＂ red-globe＂ grapes were investigated. Lightly processed grapes were stored at 0℃ after coating with （0%, 1.2%, 1.5%, 1.8%） chitosan. Dynamic changes in superoxide anion （O2^-·） producing rate, activities of superoxide dismutase （SOD）, peroxidase（POD） and catalase （CAT） were monitored, while malondialdehyde（MDA） contents and electrolyte leakage were measured. Results indicate that 1.5 % chitosan mimetic bio-membrane can slow the decrease rate of SOD, POD and CAT activities, reduce the O2^-· production and MDA accumulation, and maintain the stability of cell membrane. The ripening and senescence process of grape are decayed. Statistics analysis indicate that there is a significantly negative correlation among O2^-· and SOD, CAT activities （r = - 0. 975^＊＊ , - 0. 546^＊＊ ） and a significantly positive correlation between O2^-· and POD （r = 0. 442^＊ ）. It is suggested that the defensive enzymes play an essential role in restraining O2^-· production. 1.5 % chitosan mimetic bio-membrane can inhibit the decrease of defensive enzyme activities and O2^-· production. 1.2 % or 1.8 % chitosan mimetic bio-membranes have no beneficial effects.