Enrichment of free amino acid content and reduction of astringent taste compounds in soybean by high hydrostatic pressure

We investigated the effect of high hydrostatic pressure (HHP) on the distribution of free amino acids and isoflavones in soybean immediately after pressure treatment (100–600 MPa, 10–60 min). HHP-treatment at 200 and 300 MPa resulted in high accumulation of free amino acids. Additionally, Gly, Val, and Pro levels increased even after HHP of 400 MPa. The application of HHP-treatment to soybean decreased sources of an astringent taste such as genistein-, daizein-, and glycitein-type molecules under all pressure conditions over 200 MPa. High accumulation of free amino acids with specific pressure–time conditions would be caused by the acceleration of proteolysis and specific amino acid metabolism. We concluded that HHP alone with no subsequent storage enabled the enrichment of specific amino acids such as GABA, Glu, Lys, and Pro in soybean. Soybean with enrichment of these amino acids and improved taste should be an innovative component of functional foods.