Characteristic of hot air drying of candied prunes and representation model

The drying characteristics of candied prunes at different hot air drying temperatures were investigated, and the moisture content of the prunes in different hot air drying could be predicted by establishing the mathematical models. The results showed that drying process of prunes occurred in the falling rate period, and the moisture transfer was controlled by internal diffusion. The drying rate was significantly influenced by temperature at the range of 40-80℃ (P＜0.05). The drying rate decreased by 42.33% from 3.52×10-2 g/(g·h) to 2.03×10-2 g/(g·h) at 40℃ while the drying rate decreased by 71.17% form 14.64×10-2 g/(g·h) to 4.22×10-2 g/(g·h) at 80℃ during the drying period of 2 h. And temperature range from 80-100℃ showed lower influence on drying rate (P＞0.05) due to the case hardening effect. Modeling study indicated that Page equation could be suitable to describe the drying process of prunes according to the coefficients of determination (R2, χ2), and good agreement was found when random experimental data was compared with equation prediction. Drying rate equation calculated by the Page equation had good coincidence with experimental study. The results can provide technical bases for the control of drying technology.