Evaluation of freshness in fruit and vegetable base on their active oxygen scavenging systems -in sweet pepper fruit model-

低温贮藏是延长鲜活园艺商品货架期的最有效的贮藏方式，因为它可以减缓其新陈代谢。然而，低于临界阈值温度但高于冰点的低温会对鲜活园艺商品造成冷害。近年来，有报道称低温可诱导植物组织中的氧化胁迫，并且越来越多的证据表明低温可提高植物体内的活性氧水平，本研究测定了甜椒、梅果、甘薯和马铃薯在低温贮藏过程中抗氧化系统的变化。贮藏1℃的甜椒和甘薯，贮藏7℃的梅果，均出现了表面点蚀等冷害症状，并有所增加。贮藏1℃的甜椒和甘薯，以及贮藏7℃的梅果，过氧化氢含量均升高。但在马铃薯中，过氧化氢水平不受贮藏温度…的影响更耐用，在整个存储过程中保持不变。甜椒果实中抗坏血酸含量不受贮藏温度的影响，在贮藏过程中呈上升趋势，而脱氢抗坏血酸含量在贮藏第4天1℃时出现短暂升高，随后下降。在整个贮藏过程中，甜椒果实中还原型谷胱甘肽的含量在1℃时低于其他处理，而氧化谷胱甘肽的含量不受贮藏温度的影响，在贮藏过程中有所下降。在1℃条件下贮藏7天后，甜椒和甘薯的超氧化物歧化酶活性升高，在7℃条件下贮藏的梅果实中超氧化物歧化酶活性升高。但在马铃薯中，超氧化物歧化酶活性水平不受贮藏温度的影响，在整个贮藏过程中保持不变。这些结果表明，低温贮藏过程中，甜椒果实、青梅果实和甘薯中抗氧化系统活性的变化可能与其冷害症状的发生有关。较少

Low temperature storage is the most effective storage for extending the shelf life of fresh horticultural commodities because it slows down their metabolism. However, low temperature below the critical threshold temperature but above freezing causes chilling injury for fresh horticultural commodities. Recently, it is reported that chilling may induce oxidative stress in plant tissues, and there is increasing evidence that chilling elevates the levels of active oxygen species.In this study, we have determined changes in the antioxidant system in sweet pepper fruit, mume fruit, sweet potato and potato during storage at low temperature. Chilling injury symptoms such as surface pitting appeared and increased in sweet pepper fruit and sweet potato stored at 1 ℃, and in mume fruit stored at 7 ℃. Hydrogen peroxide levels increased in sweet pepper fruit and sweet potato stored at 1 ℃, and in mume fruit stored at 7 ℃. However, in potato, hydrogen peroxide level was not affected by storage tempe … More rature and remain unchanged throughout storage. In sweet pepper fruit ascorbate level was not affected by storage temperature and increased during storage, while dehydroascorbate level showed significant transient increase on day 4 at 1 ℃, and then decreased subsequently. Level of reduced glutathione in sweet pepper fruit was found to be lower at 1 ℃ than the other treatments throughout storage but the levels of oxidized glutathione in sweet pepper fruit were not affected by storage temperature and decreased during storage. Superoxide dismutase activity increased in sweet pepper fruit and sweet potato stored after days 7at 1 ℃, and in mume fruit stored at 7 ℃ . But, in potato superoxide dismutase activity level was not affected by storage temperature and remain unchanged throughout storage.These findings indicate that the development of chilling injury symptoms may be related to the activity of the antioxidant system in sweet pepper fruit, mume fruit and sweet potato expect in potato during storage at low temperature. Less