Effect of hot air impingement drying on drying behavior, volatile components profile, shell burst ratio, flavonoid contents, microstructure of Amomum villosum fruits

Hot air impingement drying (HAID) was employed to dry Amomum villosum (A. v.) fruit, one of the most popular traditional Chinese herbs and functional foods, under different drying temperatures, air velocities and the drying characteristics and quality were evaluated. The drying time decreased from 12 to 4 h, 10 to 8 h with the increase of temperature and velocity from 50 to 70 °C, 3 to 9 m/s, respectively. Weibull model precisely described the drying behavior. The highest total flavonoid content was obtained at 60 °C with low shell burst ratio. As for essential oil components, the relative content of monoterpenoids increased while sesquiterpenes decreased with increasing temperature. The acids and alcohols contents decreased with increase in velocity. By considering both drying time and quality, 60 °C and 6 m/s was proposed as the most favorable condition. The findings indicate HAID is a promising drying method for A. v. fruit.