Effect of drying methods and conditions on yield and physicochemical properties of gac aril powder

Abstract

The objectives of this research were to study the effects of drying methods (freeze, microwave and hot air drying) and conditions (low, medium and high) on yield, beta-carotene and lycopene content of gac aril powder. Gac aril was dried using a freeze-dryer under different drying conditions: low, medium and high (where the second stage of temperatures were 40, 50, and 60 °C) with a constant pressure and drying time (0.05 mbar and 120 min, respectively). Gac aril was dried using a microwave oven under different drying conditions: low (using 480 W microwave power for 15 min), medium (using 560 W microwave power for 13 min) and high (using 640 W microwave power for 11 min). Gac aril was also dried using a hot air oven under different conditions:  low (hot air temperature of 60 °C for 540 min), medium (hot air temperature of 70 °C for 480 min) and high (hot air temperature of 80 °C for 420 min). It was found that gac aril dried using a freeze dryer under medium and high conditions resulted in the insignificant difference of yield, beta carotene, and lycopene content (p≥0.05) with the highest value. Freeze drying of gac aril at medium condition using lower drying temperature resulted in lower energy consumption than at a higher condition. Therefore, the optimal method and drying condition of gac aril was freeze drying at medium condition (using a second stage drying temperature of 50 °C) which gave the highest yield (21.46%), and highest beta-carotene and lycopene content (10.19 and 1.98 mg/g dry weight, respectively).