Nutritional, Technological And Sensory Characteristics of Improved Cowpea (Vigna Unguiculata L.) Lines and Varieties Cultivated in Arid And Semi-Arid Lands of Eastern Kenya

Abstract

ABSTRACT Food and nutrition insecurity is a big challenge for people living in the arid and semi-arid lands (ASALs) of Kenya. They rely mostly on food aid and cereals, which are poor in key nutrients supply, especially proteins. Most crops are unable to grow well in this region due to harsh climatic conditions and poor soils. Cowpea (Vigna unguiculata L.) is a drought-tolerant highly nutritious legume which matures within a short period. Therefore, it is an excellent crop to boost protein-deficient diets and solve food and nutrition insecurity in the arid and semi-arid regions. This study analyzed ten newly bred cowpea lines IT97K-499-35, IT82D- 889, IT82D- 889-1, TEXAN PINKEYE, TX123, IT98K-205-8, IT98K-1111-1, IT97K-1042- 3, IT85F-867- 5, and IT98K-589-2 and five varieties (checks) KVU27-1, M66, K80, KUNDE MBOGA and KENYA KUNDE for the nutritional and techno-functional quality. Samples were obtained from Kenya Agriculture and Livestock Research Organization (KALRO), Katumani, Kenya. The proximate composition of the new cowpeas lines and varieties varied where protein contents ranged from 23.37-29.70%; total carbohydrates 49.37-55.74%; crude ash 2.99-3.34%; crude lipids 0.13-0.81% and crude fibre 1.40-4.34%. Minerals contents ranged from 1.97-2.69 mg/100 g for calcium, 3.23-3.90 mg/100 g for magnesium, 205.53-223.30 mg/100 g for sodium, 0.80-1.23 mg/100 g for zinc, 1071.15-1152.62 mg/100 g for potassium and 0.62-1.06 mg/100 g for phosphorus. For technological properties, improved cowpea lines absorbed water equivalent to their weights, and they were comparable to varieties grown in the region, such as K80 and KVU27-1. The results showed that cowpea lines IT97K-1042-3, TEXAN PINKIYE, IT85F-867-5, and IT82D-889 had desirable attributes such as high crude protein content, high water absorption capacities above 100%, and high volumetric expansion of 64.14%. Cooking decreased protein contents by 3.59% in TEXAN PINKIYE line and the levels of potassium, phosphorus calcium, magnesium, and zinc in cowpea grains also decreased at different levels. IT82D-889, IT85F-867-5, and IT97K-1042-3 lines recorded high retention of proteins and minerals after cooking with high consumer preference in taste, colour, aroma, flavour and general acceptability. The taste of cowpeas was the main determinant affecting the general acceptability of new cowpea lines and was well comparable with existing K80 variety. The results suggest that these cowpea lines are acceptable for home consumption and can be used to enrich foods of low protein like complementary foods. Cowpea lines IT82D-889, and IT85F- 867-5 can be approved as new varieties based on nutritive content sensory, and technological characteristics results of this study.