Effect of blanching, dehydration method and temperature on the ascorbic acid, colour, sliminess and other constituents of okra fruit

Abstract

Freshly harvested okra fruits were blanched in boiling water (with or without 0.2% sodium metablsulphite salt) and the effect of this treatment, dehydration methods and temperature on certain characteristics of okra investigated. Blanching resulted in the slight decrease in carbohydrate, fat, ash, colour components, ascorbic acid and viscosity. Besides this initial loss, blanching in sulphite solution led to the retention of more of the colour components and ascorbic acid during dehydration. All dehydrated okra samples had higher contents of carbohydrate, fat and ash but lesser contents of protein and ascorbic acid than fresh okra. Fresh okra fruits, on the other hand, had higher content of the colour pigments and were more viscous than all dehydrated products. Samples blanched prior to dehydration retained more of the colour components but were less viscous than unblanched samples. Vacuum dehydrated samples retained more ascorbic acid, colour pigment and mucilage at each of the dehydration temperatures than those from a hot air oven. High dehydration temperatures had negative effect on the colour, ascorbic acid and viscosity of okra.