Influence of pre-treatments on dehydration characteristics and quality of dehydrated okra

Okra fruits of cv. F152, either whole or sliced, were pre-treated with hot water blanching (100 degrees C for 0.5 min.), sodium metabisulphite (0.2% Na2S2O5 for 1 min.), microwave blanching (1 min.) and a control (without pre-treatment) and subjected to dehydration at two levels of temperature at 50 degrees and 55 degrees C. In general, drying time decreased with increase in temperature, but the quality was better maintained at lower temperature (50 degrees C) in most of the treatments. Moisture content reduced at faster rate with time at a higher temperature in most treatments. Rehydration and dehydration ratio of sliced fruits with Na2S2O5 (TS3), microwave blanching (TS4) and control were higher compared to dehydrated material at 55 degrees C. With regard to retention of chlorophyll and ascorbic acid, 0.2% Na2S2O5 (sliced) treatment at 50 degrees C (TS3) retained maximum ascorbic acid followed by microwave blanching of whole fruit at 50 degrees C (TW4) and control with sliced fruit at 50 degrees C (TS1). With regard to sensory attributes sliced fruits treated with 0.2% Na2S2O5 treatment at 50 degrees C showed the best result.