Thin layer drying characteristics and quality evaluation of steam blanched chrysanthemum

This article aimed to investigate the thin layer drying characteristics of the steam-blanched chrysanthemum and evaluate the quality of the resulting products. The drying was carried out at air temperatures of 60, 80, 100 and 120℃ and an air velocity of 0.5 m/s. The results showed that it was a typical process with the characteristics of falling rate drying, and drying rate was markedly accelerated with increase of temperature. The process could be divided into three stages, the first, second and third falling rate stages, and about 84% of moisture was removed in the first falling rate stage. The effective diffusivities were calculated from the data of the first falling rate stage and ranged from 1.10 to 6.44×10-9 m2/s, and the activation energy was found to be 1?829.5 kJ/kg. Midilli model better fit the drying behaviour of the first falling rate stage compared to the other eight models investigated. Steam blanching for 2 min combined with drying at 100℃ or 120℃ was recommended for the production of high quality chrysanthemum.