HIGH-PRESSURE AND FREEZING PRETREATMENT EFFECTS ON DRYING, REHYDRATION, TEXTURE AND COLOR OF GREEN BEANS, CARROTS AND POTATOES

High-pressure pretreated and frozen green beans, carrot dice or potato cubes were fluidized bed dried and compared to untreated, pressure-treated or water-blanched dried samples. Drying rates varied with pretreatments. Freezing resulted in highest drying rates. Pressure-treated and water-blanched samples retained highly acceptable colors. Freezing or hot-water blanching or high-pressure pretreatment, followed by freezing, gave good rehydration. High-pressure treatment resulted in incomplete rehydration but combined with freezing, water uptake was between 2.1 and 4.8 mL/g. Retention of cell wall structures of frozen samples during drying was presumed responsible for more efficient mass transfer. Texture measurements revealed significant effects of pretreatments. Pressure-treated samples had texture nearest that of the raw material. No major differences in color were observed.