Chemical composition and protein properties of peanuts

Abstract

Because of the shortage of food proteins throughout the world, peanut has attracted the interest as potential source of protein for human as well as animal consumption. It was shown that peanut from the four different sources contained fair amounts of protein and its products. Mineral elements analysis revealed that K, Mg, Cu, Mn, Fe and P were present in nutritionally significant amounts in all samples. Moreover, K was found in high level. The nutritional value of protein is considered by its content of essential amino acids. Peanuts contained high levels of arginine and histidine. The remaining amino acids were present in substantial quantities except methionine, tryptophan and cystine were considered low. Peanut proteins were extracted from defatted flour by different solvents: deionized water, sodium chloride and calcium chloride solutions at different pH-values. The extracting ability at pH from 1-4 was decreased and increased at pH 4-5 by raising the concentration of sodium chloride solutions, respectively. Whereas on using sodium chloride solutions at pH 6-10, the percentage of extracted protein decreased again. Calcium chloride solutions suppressed protein extractability at all pH-values tested. Both mono and divalent salts increased protein extractability at pH 4-5.5 and the extraction increased with higher salt concentrations.