Effect of processing methods on the nutritional content of three traditional vegetables leaves: Amaranth, black nightshade and jute mallow

Abstract

The study assessed changes in nutritional content of some commonly consumed traditional vegetables subjected to postharvest processes. Amaranth (Amaranthus cruentus L.), black nightshade (Solanum scabrum Mill.) and jute mallow (Corchorus olitorius L.) leaves used as vegetables were subjected to blanching, boiling and drying. The proximate composition and β-carotene content of fresh and processed leaves were determined. Amaranth, black nightshade and jute mallow leaves had 25.21%, 39.74% and 29.18% of protein, respectively. The β-carotene levels were 16.40, 25.25 and 27.74 mg/100 g for black nightshade amaranth and jute mallow leaves, respectively. The ash content was 10.57% for black nightshade, 12.40% for jute mallow and 16.33% for amaranth. Processing methods caused decreases of β-carotene and crude lipid content. Boiling for 30 min or more resulted in large loss of β-carotene. Drying under shade resulted in less loss of β-carotene than drying in cabinet at 50 and 60°C.

This article evaluates the common processing methods effects on nutritional content of three traditional vegetables (Amaranthus cruentus, Solanum scabrum, Corchorus olitorius) leaf and leaf products. Traditional vegetables constitute a major dietary source of micronutrients. Nutrient concentration of processed traditional African vegetables is dependent on the type of processing used. Shorter cooking times, cooking in less water, and using the cooking water as a part of the diet should be considered in consumption of processed vegetables to maximize product quality and nutrition. Results of this study will help to promote utilization and consumption of these traditional vegetables, which are neglected plant with great nutritional potentials.

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