STUDIES ON INFLUENCE OF VARIOUS PRE-TREATMENTS AND DRYING METHODS ON QUALITIES OF DEHYDRATED ONION FLAKES

An experiment on onion dehydration was undertaken in white onion ‘Phule Safed’ with six pre-treatments (water soaking, alum treatment and sodium chloride (Salt) with and without sulphur fumigation) and two drying methods (sun drying and through flow dehydrator). The data revealed that the pre-treatment of NaCl at 2% coupled with sulphur fumigation (1 g/kg flakes) followed by controlled drying was the best treatment combination. This combination resulted in increased transmission value (OD), pyruvic acid (26.77 µmoles/g), protein (8.64%), total sugars (53.04%) and decreased moisture content of dehydrated onion. Ash content and rehydration ratio were not affected significantly by any treatment combination. The colour, flavor, crispness and general acceptability judged by organoleptic evaluation also indicated that 2% salt coupled with sulphur fumigation and controlled drying is the most suitable combination for onion dehydration.