以美国‘紫李’为试材，测定经间歇升温和热处理后果实的褐变度、抗氧化酶活性、抗氧化剂含量、膜质过氧化水平、总酚和可滴定酸含量的变化。结果表明：间歇升温和热处理可适当恢复因冷害而降低的细胞抗氧化活性，清除活性氧自由基，减少膜脂过氧化产物丙二醛的积累，抑制多酚氧化酶和过氧化物酶活性升高，强化抗低温防御系统，阻止多酚逆境代谢发生，使冷害和褐变症状得以延缓和减轻；同时，还可抑制可滴定酸含量的减少和固酸比的上升，延缓后熟衰老。间歇升温处理，李贮藏两个月果实品质良好。初步认为，－0.5～0 ℃贮藏，每15 d加温至18～20 ℃并保持l d，是贮藏美国‘紫李’适宜的变温模式。
关键词：
李; 间歇升温; 热处理; 冷害; 褐变
Plum (cv. Purple) fruits were treated with intermittent warming and heat treatment after harvest, with their brown degree, antioxidant enzyme activities，antioxidant content, membrane peroxidation level，total phenols and titratable acid contents were investigated. The results showed that intermittent warming and heat treatment could properly restore antioxidant activity depressed by chilling injury, eliminate active oxygen free radical, reduce the accumulation of membrane peroxidation production MDA, inhibit the activities of PPO and POD, strengthen resistant system to low temperature and prevent polyphenol metabolism by adversity, thus deferred and lightened chilling injury and browning symptom. At the same time, both treatments also inhibited titratable acid content decreasing and SSC/TA increasing, postponed mature and senescence. Plum fruits could be stored in intermittent warming condition for 60 days without other treatments. We preliminarily considered that this change-temperature treatment pattern which temperature raised to 18～20℃ for 24 hours every 15 days during cold storage at －0.5～0℃ was the optimal storage condition for ‘Purple’ plum.
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