OPTIMIZATION OF STRAWBERRY DRYING PROCESS UNDER DIFFERENT PRETREATMENTS AND GEOMETRIES AT LOW TEMPERATURES

Abstract

The drying kinetics of strawberry were investigated and optimized. They affected by the strawberry geometries and the drying temperature in addition to the pretreatments including the thermal treatments and osmotic dehydration. Three geometries (whole, halve and quarter), two thermal pretreatments (hot water and microwave), osmotic dehydration (sucrose + calcium chloride and glucose + calcium chloride) and three temperatures (40, 50 and 60°C) were evaluated. The initial moisture content of the fresh strawberry samples was varied between 93.4 and 77 % (w.b). The results indicated that thehalf that treated by sucrose, Whole that treated by sucrose and hot water (80 °C) for 10 sec and half that treated by glucose, microwave (1100 W) for 10 sec at 40oC. Also, half that treated by glucose, whole that treated by sucrose and hot water (80 °C) for 10 sec and whole that treated by sucrose, microwave (1100 W) for 10 sec at 50oC. The optimum conditions at the highest temperature 60 oC were half that treated by sucrose, whole that treated by sucrose and hot water (80 °C) for 10 sec and whole that treated by sucrose, microwave (1100 W) for 10 sec.