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U.E. Inyang1 and C.I. Ike
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.
Introduction
Okra (Hibiscus esculentus) is one of the most popular and widely grown vegetable crops in many tropical countries (Rice et al., 1987). The fruits are highly mucilaginous and are used to impart a desirable slimy consistency and thickening effect to soups and stews (Ihekoronye & Ngoddy, 1985). Sliminess is a layman's term for the sticky or viscid fluid secreted by fresh okra upon cutting or blending (Uzo & Ojiako, 1980). According to Eka (1978), the slimier the okra is, the better. In addition to its use in the fresh state, the fruit is usually sliced and sun-dried by traders and consumers (without any pre-drying treatment) to preserve it for later use. Frozen storage is also common (Olorunda & Tung, 1977). In tropical countries such as Nigeria, dehydration offers a unique advantage over other methods of food preservation. It is a highly acceptable process for the preservation and reduction of weight of vegetables. Also, dehydrated foods are at least equally as nutritious as other processed foods (Salunkhe, 1974).
Blanching (with or without sulphite salt) is often the first unit operation to be followed in the preparation of most fruits and leafy vegetables for freezing and...