Abstract:

Purpose: This study aimed to determine the degradation kinetics of lutein in elm leaves during hot air drying
process at different drying temperatures. Methods: The content of lutein in elm leaves was determined by high performance
liquid chromatography (HPLC). The process of lutein degradation was fitted with a reaction kinetic equation and the
degradation kinetic parameters were resolved. Results: The content of lutein in elm leaves was (397.5 ± 27.5) μg/g fresh
weight (FW) or (1.414 ± 0.105) mg/g dry weight (DW). Analysis of kinetic data suggested a first-order reaction for the
degradation of lutein in elm leaves with the half-lives of 4.5, 3.2 and 2.8 h at 50, 60 and 70 ℃ , respectively. Increasing
temperatures from 50 to 70 ℃ enhanced the degradation of lutein during drying process. The temperature-dependent
degradation was adequately modeled on the Arrhenius equation. The activation energy value for the degradation of lutein in
elm leaves was 21.23 kJ/mol. Conclusion：Hot-air dried elm leaves at lower temperature can retain higher levels of lutein.

Key words: elm leaves, lutein, high performance liquid chromatography, degradation kinetics