High‐Pressure and Freezing Pretreatment Effects on Drying, Rehydration, Texture and Color of Green Beans, Carrots and Potatoes

Authors:
  • MEM. N. Eshtiaghi
    M. N. Eshtiaghi
  • RSR. Stute
    R. Stute
  • DKD. Knorr
    D. Knorr
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Abstract
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 pre‐treatments. 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.