Nutritional Profile, Protein Quality and the Biological Value of Raw and Cooked Pigeon Pea (Cajanus cajan) Seeds

Abstract

Pigeon pea (Cajanus cajan) of the family Fabaceae, is highly appreciated for its health benefits and nutritive value. This present study attempted to investigate the nutritional profile, protein quality and the biological value of raw and cooked pigeon pea seeds. Proximate compositions of the raw and cooked pigeon pea were determined using standard methods. The following minerals (Cr, Mg, Fe, Cu, Zn and Mn) were determined spectrophotometrically. Amino acids composition was determined using amino acid analyzer while the contents of vitamins A and C composition were determined using titrimetric method. Sixteen weaning albino rats were di vided into four groups of four rats in each. Rats in group1 were fed on casein diet, group 2 were fed on basal diet, group 3 and 4 were fed on the raw and cooked pigeon pea seeds respectively for fourteen days with the weights of the rats and the amount consumed monitored daily. The protein efficiency ratio (PER) was determined and afterwards, the rats were sacrificed and digested for further analysis. The net protein utilization (NPU) and the true digestibility (TD) were determined and used to calculate the biological value. Results of proximate analysis showed that the raw seeds contain a significantly (p < 0.05) higher contents of carbohydrates, ash and crude fiber; while the cooked peas contain a significantly (p < 0.05) higher amount of protein and lipid with no significant difference in the moisture content. There was no significant (p < 0.05) difference in the contents of copper, zinc, manganese and chromium in both the raw and cooked peas. However, the cooked pea contain a significantly (p < 0.05) higher amount of magnesium while the raw contains a significantly (p < 0.05) higher amount of iron. There were no significant differences in most of the amino acids contents of the raw pea as compared to the cooked pea. However, serine was significantly (p < 0.05) higher in the cooked pea as compared to the raw while arginine was significantly (p < 0.05) higher in the raw as compared to the cooked. There was no sig nificant difference in the contents of vitamin C present in both samples, but the cooked sample contained a significantly (p < 0.05) lower amounts of vitamin A. There was a significant (p < 0.05) increase in the body weight and PER of the animals fed on the cooked seeds as compared to those fed on raw. The TD, NPU and BV values obtained for the cooked pigeon pea seed was significantly (p < 0.05) higher than that of the raw. The cooked pigeon pea has a higher biological value with considerable nutritional value and can therefore be a viable protein supplement.