Compositional and nutritional properties of selected newly developed lines of cowpea ( Vigna unguiculata L.Walp).

Abstract

Compositional and nutritional properties of raw, boiled and steamed samples of selected advanced breeding lines of cowpea (IT8ID-699, IT82E-18, IT84S-2246-4 and TVx3236) were investigated. These lines were part of a larger collection developed by the International Institute for Tropical Agriculture (IITA) and evaluated in agronomic field trials in Nigeria. Protein quality was evaluated using weanling albino rats fed diets which were formulated to supply 10% protein using cowpea samples, with casein as a control. Raw seeds contained 20.1–25.8% crude protein, 0.99–1.96 mg polyphenol and 1.15–2.10 mg phytic acid g −1 seed flour. IT 81D-699 and TVx 3236 possessed higher crude protein contents and lower amounts of phytic acid compared with IT82E-18 and IT84S-2246-4. Boiling was shown to be more effective than steaming for reducing the levels of antinutrients and improving the protein quality of the seeds, as shown by the higher values for weight gain, protein-efficiency ratio (PER), net protein ratio (NPR) and true digestibility (TD) of the boiled samples. There were no significant ( P > 0.05 ) differences between the values obtained for PER, NPR and TD of diets containing boiled samples of IT8ID-699 and TVx 3236 and casein, indicating the nutritional superiority of these cowpea lines compared with IT82E-18 and IT84S-2246-4.