Air impingement drying characteristics and process optimization of chestnut

To solve the problems of drying in chestnut depth processing, air impingement drying technology was applied to chestnut drying in this paper. The drying characteristics of chestnut were investigated under different air temperatures (70, 75, 80 and 85℃) and air velocities (10, 12, 14 and 16 m/s). According to results of single factor tests, an orthogonal experiment was designed with the influential factors of air temperatures, air velocities and pretreatment (no blanching, 100℃ hot water blanching and 100℃ steam blanching). The results showed that the whole drying process belong to in the falling rate period, and the effect of drying temperature and air velocity on the drying rate was significant, while the effect of drying temperature was more significant than air velocity. The order of the parameters of the orthogonal experiment for increasing the L*, the b* and the sensory score of chestnut was air temperature>air velocity>pretreatment, and for decreasing the drying time of chestnut was air temperature>air velocity>pretreatment. The optimum processing parameters after orthogonal optimization were 100℃ steam blanching, 80℃ and 14m/s as its pretreatment, drying temperature and air velocity, respectively. This research can provide technical basis for applying the air impingement drying technology of chestnut.