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

低温贮藏是延长新鲜园艺商品货架期最有效的贮藏方式，因为低温贮藏可以减缓商品的新陈代谢。而低于临界阈值但高于冰点的低温会对新鲜园艺商品造成冷害。近年来，有报道称低温可诱导植物组织氧化应激，并且越来越多的证据表明低温可提高活性氧的水平。在本研究中，我们测定了甜椒果实、梅梅果实、甘薯和马铃薯在低温贮藏过程中抗氧化系统的变化。在1℃贮藏条件下，甜椒果实、甘薯和7℃贮藏条件下的梅梅果实均出现并增加了表面麻点等冷害症状。在1℃贮藏条件下，甜椒果实和甘薯的过氧化氢含量增加，在7℃贮藏条件下，甘梅果实的过氧化氢含量增加。而在马铃薯中，过氧化氢含量不受贮藏温度的影响，在整个贮藏过程中保持不变。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1℃条件下第4天呈显著上升趋势，随后呈下降趋势。在贮藏过程中，1℃处理的甜椒果实中还原性谷胱甘肽含量低于其他处理，但其氧化性谷胱甘肽含量不受贮藏温度的影响，在贮藏过程中呈下降趋势。1℃贮藏7d后甜椒果实和甘薯果实超氧化物歧化酶活性升高，7℃贮藏的梅梅果实超氧化物歧化酶活性升高。马铃薯超氧化物歧化酶活性水平不受贮藏温度的影响，在贮藏过程中保持不变。这些结果表明，低温贮藏过程中甘椒果实、甘梅果实和甘薯中抗氧化系统的活性可能与冷害症状的发生有关。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