Effect of blanching temperature and dipping time on drying time of broccoli

Abstract

Drying characteristics of broccoli was experimentally studied in cabinet-type convective dryer. Experiments were conducted using constant air velocity of 2 m/s and air temperature of 60 ℃. Drying rate increased with increasing blanching temperature and thus reduced the drying time. The experimental drying data were used to fit twelve drying models and drying rate constants and coefficients of the models were determined by non-linear regression analysis. Estimations by the Midilli et al. model were in good agreement with the experimental data obtained. Fick’s second law was used to calculate the effective moisture diffusivity, which varied from 1.987 to 3.577 × 10^-8 m²/s for the given blanching temperature range. The rehydration ratio was observed to increase with increasing blanching temperature.