【作者】 张姿；

【导师】 李进才；

【作者基本信息】 天津大学 ， 蔬菜学， 2007， 硕士

【摘要】 蔬菜采后的衰老与活性氧代谢失调有密切联系,采后热处理可以延缓蔬菜产品的衰老进程、保持品质。但是,关于采后热处理延缓蔬菜衰老的抗氧化机理尚未有系统的研究报道。本实验以甜椒果实、鲜切甜椒和青花菜为实验材料,通过考查不同热水处理对蔬菜衰老指标(颜色、失重率、叶绿素、可溶性蛋白质、丙二醛)、活性氧及抗氧化防御系统(抗氧化酶和抗氧化物质)的影响,探讨了蔬菜采后热处理的抗氧化机理。实验结果表明:甜椒果实和鲜切甜椒的55℃·1 min、50℃·4 min热处理及青花菜的55℃·30 s热处理可以有效地抑制颜色变化和失重,抑制叶绿素、可溶性蛋白质含量的减少及丙二醛(MDA)含量的增加,减少过氧化氢(H2O2)和超氧阴离子(O2-)的积累,还可以提高甜椒果实的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性,增强鲜切甜椒和青花菜的SOD、CAT和APX活性,抑制贮藏期间抗坏血酸(AsA)含量的下降。这说明适宜的采后热处理可以有效地增强蔬菜产品的抗氧化机能,减轻活性氧对细胞的毒害作用,从而延缓蔬菜产品的衰老进程。另外,鲜切甜椒的45℃·10 min热处理对衰老指标、活性氧生成及抗氧化机能都没有显著影响,而青花菜的50℃·2 min和45℃·4 min热处理对抑制H2O2产生,提高APX、CAT活性及AsA含量有一定的作用,但衰老指标的变化与对照差异较小。说明这3组热处理都不能明显地改变采后蔬菜产品的衰老进程。然而,甜椒果实的45℃·10 min热处理加快了果皮颜色的变化,加速了叶绿素、可溶性蛋白质含量的下降和MDA含量的增加,增加了衰老进程中活性氧H2O2和O2-的产生,并使甜椒的SOD、CAT和APX活性降低。说明该热处理反而加快了甜椒果实的衰老进程,并且已经对果实造成了热伤害。更多还原

【Abstract】 Abnormal metabolism of Reactive Oxygen Species (ROS) is the most important reason resulted in vegetable’s senescence. Postharvest heat treatment has been used for retarding senescence and maintaining quality on fruits and vegetables. However, antioxidative mechanism on delaying vegetable’s senescence by postharvest heat treatment hasn’t been systematically reported. Therefore, we investigated the effect of hot water treatment with different treat-time and temperature on physiological indices in peppers, pepper shreds and broccolis, in order to research the antioxidative mechanism of vegetables by postharvest heat treatment. The physiological indices included ROS contents (hydrogen peroxide and superxide), antioxidative substance content (ascorbic acid), antioxidative enzyme activity and some senescence indices, such as color, weight loss rate, chlorophyll, protein and malondialdehyde (MDA).Treatments of peppers and pepper shreds at 55℃for 1 min and 50℃for 4 min and treatment of broccolis at 55℃for 30 s retarded changes of color and weight loss rate, reduced MDA content and increased contents of chlorophyll and protein. They also alleviated production of hydrogen peroxide and superxide, enhanced ascorbic acid content and increased activities of antioxidative enzymes that included superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) during storage period. These data showed that those treatments were effective in retarding the progress of senescence because they could improve antioxidative function of vegetables and reduce accumulation of ROS.In addition, treatment of pepper shreds at 45℃for 10 min had little change in senescence indices, ROS contents and antioxidative function compared with controls. And, treatments of broccolis at 50℃for 2 min and 45℃for 4 min partly increased activities of APX and CAT, content of ascorbic acid and partly reduced hydrogen peroxide content, but their senescence indices had no significance difference with controls. These results showed that those heat treatments had no significant effect on the progress of vegetable’s senescence.Nevertheless, heat treatment of peppers at 45℃for 10 min hastened color change, increased MDA content and reduced contents of chlorophyll and protein. It also increased contents of hydrogen peroxide and superxide and decreased activities of SOD, CAT and APX. These results indicated that the treatment had already accelerated the progress of senescence and brought heat injury to peppers.更多还原