Influence of drying methods on quality of Zanthoxylum armatum DC. and mathematical modelling of the drying kinetics

In order to evaluate different drying methods on the quality of Zanthoxylum armatum DC and the change of moisture content of Z armatum during the drying process, the quality change was analyzed under three drying methods: Greenhouse drying equipment, Hot-air drying and Open sun-drying. The moisture loss was systematically recorded, converted to moisture ratio, and fitted to four semi-theoretical drying mathematical models: Lewis, Page, Henderson and Pabis, Avhad and Marchetti models. Comparisons of model fitness were using the coefficient of determination (R2), root mean square error (RMSE), mean bias error (MBE) and absolute error (MAE). The results showed that the color of Z armatum obtained by the greenhouse drying equipment was bluish green, which was significantly different from the other two drying methods (p<0.05). The numb degree difference of Z armatum obtained by the three methods was not significant(p>0.05). The opening rate is better in greenhouse drying equipment and hot air 40°C drying. The content of linalool can reach 45.5738~55.3898% of the volatile oil. The drying mathematical models fitting results showed that Avhad and Marchetti models fitted best, and the R2 of the curve ranged from 0.9677 to 0.9967, which could accurately predict the change trend of moisture ratio of Z armatum in three drying methods with drying time.