赶黄草叶茶总黄酮、游离氨基酸及槲皮素浸出动力学分析

Leaching kinetics analysis of total flavonoids,free amino acids and quercetin from Penthorum chinense Pursh leaf tea

目的:探究赶黄草叶茶冲泡过程中总黄酮、游离氨基酸及槲皮素浸出量随冲泡时间和冲泡温度的变化规律。方法:通过紫外分光光度法、高效液相色谱法(HPLC)测定总黄酮、游离氨基酸和槲皮素浸出量,使用二阶动力学模型和阿伦尼乌斯公式进行动力学拟合、动力学参数计算。结果:在60~100℃范围内冲泡60 min,总黄酮浸出量和槲皮素浸出量随冲泡温度和冲泡时间的增加而增加;60~90℃范围内冲泡60 min,游离氨基酸有相同的浸出规律,温度上升至100℃冲泡20 min后,游离氨基酸热损失较多。二阶动力学模型能较好拟合三者的浸出情况,相关系数高,冲泡温度与二阶速率常数k线性关系良好,总黄酮、游离氨基酸、槲皮素浸出活化能分别为16 628.201,23 415.139,14 975.396 J/mol。结论:赶黄草叶茶中的总黄酮、游离氨基酸和槲皮素浸出量随冲泡时间和冲泡温度变化显著,三者浸出在60~90℃范围内符合二阶动力学模型,可使用该模型对其浸出量进行预测。

Objective:To explore the changes of the total flavonoids,free amino acids and quercetin extraction amount with the brewing time and temperature during the brewing process of Penthorum chinense Pursh(PCP)leaf tea and fit the extraction kinetics equation of the three and calculate the kinetics parameters.Methods:The total flavonoids,free amino acids and quercetin were determined by ultraviolet spectrophotometry and high performance liquid chromatography(HPLC).The second-order kinetic model and Arrhenius formula were used to fit the kinetics and calculate the kinetic parameters.Results:The leaching amount of total flavonoids and quercetin increased with the increase of the temperature and the brewing time in the range of 60~100℃for 60 min.When brewing for 60 min at 60~90℃,the free amino acids had the same leaching law.When the temperature rised to 100℃,the heat loss of free amino acids was large after brewing for 20 min.The second-order kinetic model could fit the leaching amount of the three substances well with the high correlation coefficient.Linear relationship between temperature and second-order rate constant k was good.The activation energies of total flavonoids,free amino acids and quercetin were 16628.201,23415.139 and 14975.396 J/mol.Conclusion:The extraction amount of total flavonoids,free amino acids and quercetin in PCP leaf tea changed significantly with the brewing time and temperature,and the extraction amount of the three was in line with the second-order kinetic model in the range of 60~90℃,which can be used to predict the extraction amount.