Beta-aminoisobutyric acid (BAIBA) and branched-chain amino acid (BCAA) have recently received considerable attention due to their various health benefits. In this study, the hydrolysis characteristics of chicken breast meat by eleven commercial proteolytic enzymes were studied to evaluate the effect of protease types, reaction pH (5-8), temperature (40-70℃), time (2-24 h), enzyme concentration (0.25-8%) and the effect of combined enzymes for the preparation of BAIBA- and BCAA-enriched chicken breast hydrolysates. The content of BAIBA was higher in hydrolysates by prozyme 2000P (38.7 mg/g, dry weight base), foodpro alkaline protease (30.2 mg/g) and alcalase (26.4 mg/g) while the BCAA content was higher in prozyme 2000P (109.0 mg/g), flavourzyme (86.1 mg/g) and sumizyme LP (62.9 mg/g). As the effects of reaction pH, temperature, time, and amount of added enzymes, the optimum condition for the preparation of both BAIBA- and BCAA-enriched hydrolysates were the following; reaction pH 6-7, temperature 50℃, reaction time 8-16 h and enzyme amount 4% (w/w) based on the dried chicken breast. However, no meaningful significant increases of BAIBA and BCAA were observed when hydrolyzed with two combined enzymes. The results suggest that commercial proteolytic enzymes can be applied for the preparation of BAIBA- and BCAA-enriched chicken breast hydrolysates.
Two angiotensin I-converting enzyme (ACE) inhibitory peptides were isolated from chicken breast protein hydrolysate. The purification steps involved Sephadex G-25 gel chromatography to eliminate the high molecular weight proteins and peptides and isolation by preparative (prep.)-HPLC chromatography. The two peptides were isolated with high purity by chromagraphic methods and two peptides showed ACE inhibitory activity in a concentration-dependent manner. Based on the results of analyzing the amino acid composition by acid hydrolysis, the two isolated compounds were expected to be peptides composed of 13 and 14 amino acids, respectively.