IMPROVING THE QUALITY OF HOT-AIR-DRIED SAPODILLA BY COMBINED OSMOTIC-MICROWAVE PRETREATMENT

Dehydration of fruits with heat air is commonly used to preserve the products and extend shelf-life. However, long drying times and poor quality of dried products are frequent problems. The present work expected that the combination of osmotic dehydration and microwave drying as a pretreatment process could be shortly hot-air drying time and improve the quality of dried products. The yellow-green and 5-mm-thick slices were treated with combined osmotic-microwave process before dried consecutively with hot-air oven at 60°C. It resulted in a significant reduction in the drying time of hot air process. When samples were soaked with 50% (w/v) sugar and 5% (w/v) salt for 2 h and then followed with microwave (540 W) for 12 min, a significant reduction in the drying time of hot air process was observed from 420 min to 120 min, as compared to non-pretreated control. It was also found that the fruits obtained discontinuous microwave energy gave the dried products, which had better appearance than those obtained continuous microwave energy. Thus, it is possible to obtain dried and intermediate moisture sapodilla products that have better quality than hot-air dried products with saving energy.