Nutritional retention and browning minimisation in dehydrated onion slices through potassium metabisulphite and sodium chloride pre-treatments

The global demand for dehydrated onion is on the rise, driven by the increasing consumer preference for ready-to-eat convenience foods. This study focused on enhancing the quality and functional properties of dehydrated onion slices (cv. Pusa Shobha) through different pre-treatment and drying conditions. Fresh onion slices were subjected to pre-treatment using NaCl (3%, 5% and 7%) and KMS (0.3%, 0.5% and 0.7%) solutions for 10 min, followed by tray drying at 50 degrees C, 60 degrees C and 70 degrees C temperatures for varying durations of 14, 12 and 10 h, respectively. Based on physicochemical and functional properties, onion slices pretreated with 5% NaCl + 0.5% KMS and dehydrated at 60 degrees C for 12 h retained higher bioactive compounds like total phenols (166.32 mg GAE 100 g-1 DW), total flavonoids (28.94 mg QE g-1 DW), ascorbic acid (12.45 mg 100 g-1 DW), quercetin (172.88 mu g g-1 DW) and total antioxidant activity (24.59 mu mol TE g-1 DW). Additionally, it maintained superior sensory acceptability with higher pungency (7.15 mu mol g-1 DW), dehydration ratio (9.25%), rehydration ratio (5.20%), lower non-enzymatic browning (0.36) and moisture content (5.75%). Hence, the optimised treatment of 'Pusa Shobha' slices with 5% NaCl + 0.5% KMS, followed by dehydration at 60 degrees C for 12 h, yields dehydrated onion slices with superior bioactive compounds, sensory acceptability, and enhanced functional properties. The findings of his research offer valuable technology for the food industry, providing a practical and efficient method to produce high-quality dehydrated onion slices. This study investigated the effect of pre-treatment and drying temperature on physicochemical quality, functional characteristics, and overall acceptability of dehydrated onion slices. image