Abstract

                                Influence of dehydration temperatures and pre-treatment levels to control browning and preservation were assessed by dehydrating Pusa White onion slices at 50°, 60° and 70°C temperatures with 0.2, 0.3 and 0.4 per cent of potassium metabi-sulphite as a pre-treatment. The time required for dehydration was comparatively lesser for the pre-treated samples than control in all the selected temperatures. From the biochemical analyses it was observed that the ascorbic acid retention was comparatively higher at 50°C with 0.4 percent sulphitation level; the sugar content was significantly higher at 50°C in control samples and the non-enzymatic browning was comparatively lesser at 60°C with 0.3 percent sulphitation level. From the organoleptic study it was observed that the onion flakes dehydrated at 60°C with 0.3 percent sulphitation level scored the maximum points. A progressive increase in moisture content, reduction in ascorbic acid and rehydration ratio were also observed during storage.

Key words : Dehydration, Sulphitation, Non-enzymatic browning. Organoleptic evaluation