FAR INFRARED–VACUUM AND –CONVECTION DRYING OF WELSH ONION

摘要: The drying of welsh onion by a far–infrared (FIR) heater under reduced pressure and convective conditions were studied to understand the characteristics. effects radiant power input vacuum levels on drying phenomenon were investigated. In addition, rate as function moisture content was studied vis–a–vis drying qualities such rehydration potential, shrinkage, color change. When samples dried from about 10.1 to 0.05 w/w dry basis content, three characteristic periods, namely, rising, constant, falling were obtained. increased with increasing higher in reduced–pressure environment than condition. With 0.17 W/cm2 input, 50% vacuum operation than There shrinkage concomitant potential and superior quality at lower FIR–vacuum system FIR–convection system.