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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。
Objective To explore the metabolic changes of chloroplast pigment during storage and the kinetic model of chlorophyll degradation during storage of Chinese cabbage. Methods The Chinese cabbage collected from postharvest “Shanghai Qing” was used as test material and stored at room temperature (20 ℃), low temperature (2 ℃) and ice temperature (-0.5 ℃) respectively. The total chlorophyll, chlorophyll a , Chlorophyll b, β-carotene and lutein metabolism, and chlorophyll degradation kinetic model fitting. Results The total chlorophyll, chlorophyll a, chlorophyll b, β-carotene and lutein in Chinese cabbage during storage were all degraded in different degrees. Storage at low temperature and ice temperature slowed down the degradation, of which the slow-temperature storage was the best. The ratio of chlorophyll a content to chlorophyll b content, the ratio of β-carotene content to total chlorophyll content, and the ratio of lutein content to total chlorophyll content at room temperature all showed different degrees of increase, while the low temperature and ice temperature storage The ratio of lutein to total chlorophyll content in the environment showed a downward trend overall, but the decrease was not significant after 6 days of storage. In addition, the degradation reaction of chlorophyll conformed to the zero-order kinetic reaction model, and the Adj.R2 fitting coefficients were all greater than 0.93, the activation energy of degradation was 95.53 kJ / mol and the degradation kinetic model was k = 6.51 × 1015 · exp 9.553 × 104 / RT). Conclusion The metabolic changes of chloroplast pigment in storage of post-harvest Chinese cabbage are greatly influenced by the storage temperature, and the chlorophyll degradation reaction accords with the zero-order kinetic reaction model.