关键词: 桔梗切片, 热风干燥, 干燥特性, Weibull分布函数

Abstract: In order to improve the drying rate and quality of Platycodon grandiflorum slices, by using hot-air drying technology, the effects of drying temperature and slice thickness on the drying characteristics of Platycodon grandiflorum slices were studied, and the Weibull distribution function was used to fit the drying curve and calculate the effective water diffusion coefficient, evaluated the quality of dried products by comparing the water activity and color under different drying conditions. The results showed that: the drying   was mainly  at lower speed, and increased the hot-air temperature and decreased the slice thickness to improve the drying rate. The suitable parameters of hot-air drying were drying temperature  55 ℃ and slice thickness  4 mm. The Weibull distribution function was used to simulate the drying data, and the determination coefficient R2 was 0.995 3~0.999 5, and the sum of squares of deviations 2 was 0.449 9×10-4~4.136 3×10-4, which could fit the hot-air drying process of platycodon slices well. Scale parameter α was inversely proportional to hot air temperature. The shape parameter β was mainly affected by slice thickness. Hot-air drying technology could significantly increase the chromatic aberration of platycodon grandiflorum and reduce the water activity of dry products. By comparing the microstructure of dry products under different drying conditions, it was found that the hot air treatment could reduce the surface cell damage and increase the drying rate. The results provided reference for the industrial production of platycodon grandiflorum under hot-air drying condition.

Key words: Platycodon grandiflorum slice, hot air drying, drying characteristics, Weibull distribution function