Comparative study on drying characteristic, moisture diffusivity, and some physical and nutritional attributes of blanched carrot slices

Comparative study of drying characteristic, moisture diffusivity, and quality attributes of blanched carrot slices (BCS) dried by hot-air and short- and medium-wave infrared radiation (SMIR) were investigated. SMIR drying could shorten drying time by 78-84% as compared to the hot-air process at the same temperature. In both drying methods, drying occurred mainly in the falling rate period, and the Page model was the best in describing the drying processes BCS. Effective moisture diffusivity (D-eff) was significantly affected by drying methods, values of D-eff in SMIR drying were 4-5 times higher than that of hot-air drying. The activation energy values of BCS were 28.64 and 22.30 kJ.mol(-1) for hot-air and SMIR drying, respectively. Compared with hot-air drying, BCS dried by SMIR gave better color, higher rehydration ratio, and greater -carotene retention. Comparison results indicated SMIR drying was a more promising drying method than hot-air drying. Practical applicationsShort- and medium- wave infrared radiation (SMIR) drying, with wavelength in the range of 76-4 m, is an emerging drying technology which has many advantages, such as maintaining product quality, increasing the drying rate. As representatives of the traditional and innovative drying method, hot-air and SMIR drying were chosen to conduct comparative study. Results showed that blanched carrot slices dried by SMIR showed higher drying efficiency, better integrated quality than hot-air drying. This study provided the reference that SMIR drying could be a promising drying methods for agro-products.