Drying model, kinetics, and stability of four rattan Chinese medicinal materials / 中草药

ABSTRACT

Objective: To establish the common model of four kinds of rattan traditional Chinese medicinal materials (TCMM) (Paederiae Scandens Caulis, Lonicerae Japonicae Caulis, Polygoni Multiflori Caulis, and Ipomoea batatas Caulis) determinate the drying kinetic parameters, and study the stability of active ingredients in the drying process. Methods: The experimental data of four rattan TCMM were fitted to the nine thin layer models (Page, Wang and Singh, Two-term exponential, Newton, Logarithmic, Aghbashlo, Two-term, Midilli, Diffusion approach) at the temperature of 40, 50, 60, and 70 ℃. R2, χ2, and RMSE were used as the criterion of fit. Fick diffusion law was used to calculate the drying dynamical parameters. Based on the principle of chemical kinetics, the stability of active ingredients in the drying process was studied. Results: Aghbashlo model was the best one to describe drying process of four rattan TCMM. The effective moisture diffusion coefficients D and activation energy Ea of four rattan TCMM were between 1 × 10−10 and 1 × 10−9 m2/s and 40—50 kJ/mol respectively. The degradation reactions of ursolic acid, THSG, and polysaccharide conformed to the first-order kinetic equation. The content of chlorogenic acid increased with the drying temperature and drying time increased. Conclusion: The drying dynamical parameters values of TCMM with different parts have different ranges, their drying process should be described by a common model. The quality of TCMM was affected greatly by drying process.