Production of Angiotensin I-Converting Enzyme-Inhibitory Peptides in a Freeze-Thaw Infusion-Treated Soybean

Freeze-thaw infusion (FI) is a new technology involving the rapid impregnation of food materials with enzymes under reduced pressure. An FI method employing protease was used to produce an angiotensin I-converting enzyme (ACE)-inhibitory peptide within soybean. Protease N “AMANO” G, the enzyme used for this method was selected after testing 11 commercial enzymes. The ACE-inhibitory peptide isolated from FI-treated soybean was identified by a three-step process involving HPLC and LC/MS/MS. Ile-Tyr was isolated as the dominant component of this ACE-inhibitory peptide, and was present at a concentration of 0.11 mg/g in FI-treated soybean.