OSMOTIC-CONVECTIVE DEHYDROFREEZING PROCESS FOR DRYING KIWIFRUIT

Osmotic and convective dehydrofreezing were studied to determine sugar concentration, ascorbic acid loss, and texture changes in dried and d ehydrofrozen kiwifruit. Two concentrations of sucrose (60 degrees and 72 degrees Brix) were used as osmotic solutions after convective air d rying. Time needed to reach desired moisture was reduced with combined drying compared with osmotic drying. Firmness was evaluated by the ma ximum force from a back extrusion test. A reduction in maximum force w as observed after freezing, as compared with fresh and dried fruit. Ad dition of ascorbic and citric acid as antioxidants in the osmotic solu tion prevented browning, and significant loss of ascorbic acid during osmotic drying. Air drying at 30 degrees C produced distinguishable co lor changes.