Abstract
This study examined the effects of vacuum, ethanol pretreatment, and infrared-hot air drying methods on the characteristics and quality of scallion slices. The pretreatment of scallion includes four conditions: 1) Control: soaking in distilled water under normal pressure, 2) Ethanol: soaking in 75% ethanol under normal pressure, 3) Water + VC: soaking in distilled water under a vacuum of 0.6 bar, 4) Ethanol + VC: soaking in 75% ethanol under a vacuum of 0.6 bar. The pretreatment times were 5, 10, 20 and 30 min. The drying process was done in an infrared hot air drying oven at 60 degrees C. The ethanol pretreated samples exhibited better rehydration, odor, vitamin C retention, bactericidal effect and significantly reduced drying time. Water + VC samples showed better scallion morphology and color. Ethanol + VC samples showed the combined advantages of ethanol and Water + VC pretreatments. Therefore, Ethanol + VC pretreatment can significantly improve the drying rate and quality of scallion.