The effects of post-harvest handling on physical, chemical and functional properties of cowpea (Vigna unguiculata) seed

Abstract

Damage by insects and mould, proximate composition, cooking rate and functional properties of sun-dried and stored cowpea (Vigna unguiculata) seeds were evaluated. Cowpea samples spread between black polythene films were placed on cement (CS), Wooden (WS) and corrugated iron sheet (CIS) surfaces, respectively, and sun-dried for 5 h. Storage lasted 6 months in jute and polythene bags. Results show that sun-drying and storage in polythene bags significantly (p< 0.05) lowered the extent of insect and mould damage, moisture-loss at drying, emulsion activity and stability, foaming capacity and foam stability. Treated cowpea seeds could be stored safely for about 5 months. In contrast, storage in jute bags significantly (p< 0.05) lowered only foam stability. Moisture loss during sun-drying principally lengthened cooking time as storage duration progressed. Therefore, assessment of moisture content before and during storage is a preferred quality index of cowpea seeds stored in polythene bags. # 1999 Society of Chemical Industry 30% in a 6 month storage has been reported. 2 The choice of appropriate drying techniques for food crops in the tropics is based on cost. Sun-drying is attractive to the small-scale farmers who are respon- sible for the production and preservation of the majority of the food crops in developing countries. Spreading of soyabean seeds on cement floors covered with black polythene film in order to enhance the retention of solar energy during sun-drying is a recent practice. 3 The effect of heat treatment on functional properties of raw and processed brown bean (Cana- valia rosea DC) flour has been reported. 4 The quality of cowpeas dried on different surfaces, such as cement, wood and corrugated iron sheet, has not been investigated. The objectives of the present study were, therefore, to evaluate the effects of sun- drying using the surfaces mentioned on the rate of