Assessment of the protein quality of twenty nine grain amaranth (Amaranthus spp. L.) accessions using amino acid analysis and one-dimensional electrophoresis

Abstract

Protein deficiency in diets adversely affects growth and development. Novel source of high quality protein and its utilization is essential in improving the nutritive status of the vulnerable groups. Total protein content and protein fractions of 29 amaranth accessions and a soybean cultivar used as reference were determined. The amino acid composition of ten representative accessions of amaranth was also determined. Total protein content ranged from 11.77 to 19.01 g/100 g. One-dimensional gel electrophoretic separations revealed albumin, globulin and glutelin as the major protein fractions; prolamin was not detected. All accessions had similar seed protein electrophoretic profile, ranging from 6.5 to 66 kDa. The glutelin fraction of all amaranth accessions shared similar electrophoretic bands with the soybean cultivar at the 4 to 14, 24 to 36 and 65 to 66 kDa regions. All amaranth accessions contained a good balance of the nine essential amino acids. The sum of essential amino acids ranged from 31.22 to 44.88 g/100 g and 60.87 g/100 g total protein in amaranth and soybean, respectively; limited only in tryptophan and leucine for amaranth, and methionine for soybean. Amaranth is a good source of high quality protein and may serve as a nutritive substitute for some cereals in functional foods.

Keywords: Amaranthus, amino acid, gel electrophoresis, protein quality, protein fractions

African Journal of Biotechnology Vol. 12(15), pp. 1802-1810