ผลของการอบแห้งกระชายดำด้วยไมโครเวฟร่วมกับอากาศร้อนต่อพฤติกรรมการอบแห้ง อุณหภูมิ สี การหดตัวและการสิ้นเปลืองพลังงานจำเพาะ

The objective of this paper is to study effect of black galingale drying by microwave-hot air combination on drying time, surface temperature, color, shrinkage and specific energy consumption. A 1.1 kW heater and a 850 W microwave ovens were used. The drying conditions were conducted at different drying conditions of microwave powers of 100, 180, 300, 450 W and hot air temperature of 40, 50, 60°C. The superficial air velocity of approximately 0.5 m/s was fixed throughout the experiment. The initial moisture content of black galingale about 80.14 % wet basis and it was dried until the final moisture content was 2.88 % wet basis. It was found that the highest microwave energy consumption resulted in the shortest drying time. At the highest temperature of drying of MW450W+HA60°C the surface temperature of black galingale of 85°C and the temperature conditions were conducted at different drying method, it was found that whiteness (L*), redness (a*) and yellowness (b*) of black galingale were significantly (P<0.05) different and the highest microwave energy consumption which in the resulted in the lowest value of shrinkage and specific energy consumption. [ABSTRACT FROM AUTHOR]