Enzymatic hydrolysate of African yam bean seed protein isolate was prepared by treatment with alcalase. The hydrolysate was further fractionated into peptide sizes of <1, 1–3, 3–5 and 5–10 kDa using membrane ultrafiltration. The protein hydrolysate (APH) and its membrane ultrafiltration fractions were assayed for in vitro antioxidant activities. The <1 kDa peptides exhibited significantly better (p < 0.05) ferric reducing power, diphenyl-1-picryhydradzyl (DPPH) and hydroxyl radical scavenging activities when compared to peptide fractions of higher molecular weights. The high activity of <1 kDa peptides in these antioxidant assay systems may be related to the high levels of total hydrophobic and aromatic amino acids. In comparison to glutathione (GSH), the APH and its membrane fractions had significantly higher (p < 0.05) ability to chelate metal ions. In contrast, GSH had significantly greater (p < 0.05) ferric reducing power and free radical scavenging activities than APH and its membrane fractions. The APH and its membrane fractions effectively inhibited lipid peroxidation, results that were concentration dependent. The activity of APH and its membrane fractions against linoleic acid oxidation was higher when compared to that of GSH but lower than that of butylated hydroxyl toluene (BHT). The results show potential use of APH and its membrane fractions as antioxidants in the management of oxidative stress-related metabolic disorders and in the prevention of lipid oxidation in food products.

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The effect of mixing different sources of vegetable proteins from legumes in the preparation of infant weaning foods was investigated. Melon, cowpea and soya as sole protein sources or as a mixture were fed to 60 albino rats. A milk powder-based commercial product (Cerelac) was used as control diet. The mixture of the vegetable protein diet compared favorably with the control diet in terms of growth rate, protein efficiency ratio (PER) and net protein ratio (NPR) and also ensured optimum nitrogen content in liver, kidney and muscle tissues. In contrast the use of individual protein sources failed to support satisfactory growth and were inferior to those in animals fed with the control or mixed diets. It was thus concluded that in the developing countries an application of such a mixture of vegetable proteins may be suitable in the preparation of weaning foods.

Purpose -The purpose of this paper is to nutritionally evaluate the potency of complementary food produced by mixing different sources of vegetable and animal protein together. Design/methodology/approach -Maize (carbohydrate), peanut (groundnut) and crayfish (Euastacus spp) were the sole energy and protein sources, respectively. Diet 1 (Basal); diet 2 (groundnut-fermented-maize (ogi) 1:9); diet 3 (crayfish-ground-nut-ogi, 1:1:9); diet 4 (crayfish-ogi, 1:9); diet 5 control (Nutrend). The formulated complementary diets were fed to 30 albino rats. A commercial product (Nutrend) manufactured by nestle plc was obtained at a local supermarket, Ile-Ife, Nigeria and was used as standard diet. Findings -The result showed the growth rate (non-protein diet) decreased from 37.962-36.910; and the growth rate (protein diet) increased from 37. 270-54.544, 37.770-82.662, 37.900-78.570, and 37.636-80.521 for diets 1 2, 3, 4 and 5, respectively. Protein efficiency ratio (PER), for diets 1 2, 3, 4 and 5 were nil, 1.45, 3.30, 3.15, and 2.94, respectively. Net protein ratio (NPR), for diets 1 2, 3, 4 and 5 were nil, 0.85, 2.78, 2.59, and 2.45, respectively. The average nitrogen retained in various organs of experimental animals, such as liver, kidney and muscle of the diets 1 2, 3 4 and 5 were 35.52, 33.55, 33.58: 48.32, 48.40 48.68: 55.70, 53.20, 56.08: 52.30, 50.48, 54.65: and 56.76, 44.63, 56.80, respectively. The formulations compared to control were found superior in terms of growth rate, PER, NPR and ensure optimum nitrogen content in the liver, kidney and tissues. Originality/value -The paper's findings show that the complementary food formulations which are not expensive, locally available, and affordable, could be produced from plant and animal sources and may be suitable to eradicate protein energy malnutrition (PEM).