Nutritional quality and utilization of local and improved cowpea varieties in some regions in Tanzania

Abstract

Cowpeas are grown for their leaves and grains both of which are used as relish or side dishes together with the staple food. Little information is available on the nutritional quality of local and improved cowpea varieties grown in Tanzania as well as the recipes in which they are ingredients. This study was done to investigate cowpea utilization in Iringa and Dodoma regions of Tanzania. A cross-sectional survey was carried out where a total of 517 farmers were interviewed using a pre-tested structured questionnaire. Proximate and mineral composition of different varieties of cowpea grains and leaves were determined using standard AOAC methods. More than half of the households interviewed consumed cowpeas in one or more forms. Most cowpea recipes included them as relish being eaten with rice or stiff porridge (ugali), a mixture of dehulled maize and cowpea grains (kande) and cowpea buns (bagia). Improved cowpea varieties had relatively higher fat content ranging from 8 to 11.2% compared to local varieties (5.4%). Local cowpea grains had higher levels of calcium varying between 958.1 and 992.4 mg/kg than dehulled cowpea (360 to 364 mg/kg) and cowpea flour (303 to 311 mg/kg). Zinc ranged from 32.6 to 31.5 mg/kg, while iron content ranged from 27.6 to 28.9 mg/kg. Fresh cowpea leaves had the highest levels of minerals, with calcium varying between 1800.6 and 1809.6 mg/kg, zinc between 36.1 and 36.0 mg/kg and iron between 497.0 and 499.5 mg/kg. The improved cowpea varieties, IT99K-7212-2-1 (23.8 mg/kg) and IT96D-733 (21.2 mg/kg) had the highest iron content. IT99K-7-21-2-2-1 (32.2 mg/kg) and IT97K499-38 (28.3 mg/kg) had the highest zinc concentration. The bagia (cowpea buns), prepared in Dodoma had higher mineral composition, calcium (893mg/kg), zinc (13.7 mg/kg) and iron (16.3 mg/kg) compared to those prepared in Iringa; calcium (32.6mg/kg), zinc (4.96 mg/kg) and iron (5.2 mg/kg). The cowpea daily per capita consumption for the majority of the households surveyed ranged from 41 to 200 gm. The contribution of micro and macro nutrients is significant for both developed lines and local varieties but with leaves having greater mineral content than the grains; hence, promotion of consumption of the leaves alongside the grains would be of nutritional advantage. Additionally, farmers should be encouraged to plant the higher yielding cowpea varieties and preferred local varieties.