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°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° and 55°C. In general, drying time decreased with increase in temperature, but the quality was better maintained at lower temperature (50°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°C. With regard to retention of chlorophyll and ascorbic acid, 0.2% Na₂S₂O₅ (sliced) treatment at 50°C (TS₃) retained maximum ascorbic acid followed by microwave blanching of whole fruit at 50°C (TW₄) and control with sliced fruit at 50°C (TS₁). With regard to sensory attributes sliced fruits treated with 0.2% Na₂S₂O₅ treatment at 50°C showed the best result.