Determination of the Protein Quality of Three New Northern Adapted Cultivars of Common and Miso Type Soybeans by Amino Acid Analysis

The total protein and amino acid contents of three new northern adapted soybean cultivars, namely Apache, Baron, and a miso type Maple Belle and its older male recurrent parent Evans, were compared as potentially useful indices for assessing their protein quality from their FAO/WHO amino acid scoring pattern. The total protein contents, although similar, were statistically significantly different ( P > 0.05), varying from 30.1% in Baron to 31.2% in Evans, 32.3% in Apache, and 31.5% in Maple Belle. All four soybean cultivars contained an excellent balance of essential amino acids (EAA), i.e., EAA 9 = 46−46.6% compared to the FAO/WHO reference protein pattern value of 33.9% for a 2−5-year-old child. All were limited only in methionine, and to a lesser extent in isoleucine and valine, and had a protein digestibility corrected amino acid score of 91% compared to the values obtained for hen's whole egg (97%). These results indicate that an accurate calculation of protein quality of soybean seeds and other legumes can be made from their amino acid composition.