冷害对荔枝果皮膜脂过氧化和保护酶活性的影响

Effect of chilling injury on membrane lipid peroxidation and activities of cell defense enzyme in litchi pericarp

以广东省优良品种‘糯米糍’为试材,研究了荔枝Litchi chinensis果实在冷害温度贮藏过程中果皮膜脂过氧化与保护酶变化规律.结果表明,糯米糍在0℃下21 d时果面已经出现水渍状褐斑,褐变指数2.45,果皮细胞相对电导率达到56.4％,货架期仅6h,表明果实已经遭受不可逆的冷害.0℃下14 d后果皮超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(AsA-POD)和过氧化氢酶(CAT)活性下降,协调紊乱,导致果皮的MDA含量迅速增加.3℃冷藏7-14 d的果实SOD、CAT活性维持较高的水平,不表现冷害,28 d时出现衰老.

Litchi cultivar' Nuomici' was used to study membrane lipid peroxidation and activities of cell defense enzyme in pericarp when stored at (0±0.2) and (3±0.2) ℃ . Fruits stored at 0 ℃ for 21 days developed irreversible chilling damage. The chilling-injured fruits presented water-logging browning spots, relative conductivity of pericarp membrane was 56.4% , browning index 2.45 and shelf life only 6 h. During this process, the activities of superoxide (SOD), ascorbic acid-peroxidase (AsA-POD ) , catalase (CAT) and peroxidase (POD) decreased or worked unbalance, which accumulated free radical and enhanced lipid peroxidation, as a result, malondialdehyde (MDA) content went up quickly. The SOD and CAT activities of fruits stored at 3 ℃ maintained higher level during 7-14 days and developed browning only after 28 days without chilling injury.