Studies on the Degradation Process of Soybean Protein during Miso Making

Part III Changes in amino acid content during miso making

Abstract

Change in total and free amino acids during miso making was studied. Free lysine, histidine, leucine, isoleucine, valine, tyrosine, and glycine increased remarkably in first one or two weeks of fermentation, while the change was very small in latter part of fermentation. Glutamic acid, aspartic acid, and proline increased linearly for 50 days of fermentation at 30°C. The extent of liberation was high for lysine, arginine, threonine, serine, proline, and tyrosine, and low for valine, histidine, glycine, and aspartic acid. The liberation of glutamic acid was the lowest among examined. Free arginine decreased after 50 days increase which was considered to be due to the action of microorganisms.