采后小白菜叶绿体色素含量变化及其叶绿素降解动力学的研究

Research on chloroplast pigment metabolism and chlorophyll degradation dynamics of post-harvest pakchoi(Brassica chinensis L.)

中文关键词:  叶绿体色素  小白菜  动力学模型  Arrhenius方程

英文关键词:chloroplast pigment  pakchoi  kinetic model  Arrhenius equation

中文摘要:

      目的 探究采后小白菜贮藏过程中叶绿体色素的代谢变化及其叶绿素降解的动力学模型。方法 以采后“上海青”小白菜为试材, 分别将其贮藏于室温(20 ℃)、低温(2 ℃)及冰温(-0.5 ℃)条件下, 研究其总叶绿素、叶绿素a、叶绿素b、β-胡萝卜素及叶黄素的代谢变化, 并对其叶绿素的降解进行动力学模型拟合。结果 采后小白菜贮藏过程中总叶绿素、叶绿素a、叶绿素b、β-胡萝卜素和叶黄素均发生不同程度的降解, 低温和冰温贮藏均可减缓其降解, 其中冰温贮藏减缓效果最佳。叶绿素a含量与叶绿素b含量的比值、β-胡萝卜素含量与总叶绿素含量的比值以及室温贮藏条件下叶黄素含量与总叶绿素含量的比值均呈现不同程度的上升趋势, 而低温和冰温贮藏环境中的叶黄素含量与总叶绿素含量的比值总体则呈现下降趋势, 但贮藏6 d后下降不显著。此外, 叶绿素的降解反应符合零级动力学反应模型, 拟合调整决定系数(Adj.R2)均大于0.93, 降解活化能为95.53 kJ/mol, 降解动力学模型为k=6.51×1015?exp(9.553×104/RT)。结论 采后小白菜贮藏过程中叶绿体色素的代谢变化受贮藏温度影响较大, 其叶绿素降解反应符合零级动力学反应模型。

英文摘要:

      Objective To explore the chloroplast pigment metabolism and chlorophyll degradation kinetic model of post-harvest pakchoi in the process of storage. Methods The post-harvest pakchoi(Shanghai qing)was selected as materials. They were stored at room temperature (20 ℃), low temperature (2 ℃) and ice temperature (?0.5 ℃), and the metabolic changes of their total chlorophyll, chlorophyll a, chlorophyllb, β-carotene and xanthophyll were studied. The kinetic model of chlorophyll degradation was studied. Results The total chlorophyll, chlorophyll a, chlorophyll b, β-carotene and xanthophyll of post-harvest pak-choi were all degraded at certain degrees in the process of storage, and the low temperature and ice temperature could slow down their degeneration. The effect of ice temperature storage on the degradation was best. The ra-tios of chlorophyll a content to chlorophyll b content, β-carotene content to total chlorophyll content and the ra-tio of xanthophyll content to total chlorophyll content at room temperature had an upward tendency at certain levels, while the ratio of xanthophyll content to total chlorophyll content at low temperature and ice tempera-ture had a downward trend during the storage, and the downward trend was not significant after 6 d. In addition, the chlorophyll degradation reaction was accorded with the characteristics of zero order kinetic model, and fit-ting adjusted coefficient of determination (Adj.R2) were all above 0.93, the degradation activation energy was 95.53 kJ/mol, the degradation kinetic model was k=6.51×1015?exp(9.553×104/RT). Conclusion The chloroplast pigment metabolism of post-harvest pakchoi in the process of storage was largely influenced by the storage temperature, and its chlorophyll degradation reaction was accorded with zero order kinetic model.