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

Abstract

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 16 628.201, 23 415.139 and 14 975.396 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.

Keywords

• penthorum chinense pursh
• substitutional tea
• dynamics
• total flavonoids
• freeamino acid
• quercetin