Bioavailability of angiotensin I-converting enzyme (ACE) inhibitory peptides derived from Virgibacillus halodenitrificans SK1-3-7 proteinases hydrolyzed tilapia muscle proteins

- The highest ACE inhibition was found in the hydrolysates of tilapia mince.
- In vitro gastrointestinal digestion reduced ACE inhibitory activity of the hydrolysate.
- In vitro digestion enhanced the permeability of the peptides across Caco-2 cells.
- The novel transported peptide with the highest ACE inhibition was identified to be MCS.

The angiotensin I-converting enzyme (ACE) inhibitory activity of protein hydrolysates from tilapia muscle fractions, namely mince (M), washed mince (WM), and sarcoplasmic protein (SP), were investigated. Each fraction was hydrolyzed by Virgibacillus halodenitrificans SK1-3-7 proteinases for up to 24 h. After 8 h of hydrolysis, the M hydrolysate (48% degree of hydrolysis (DH)) showed the highest ACE inhibitory activity, with an IC50 value of 0.54 mg/ml, while the SP hydrolysate exhibited the lowest DH and ACE inhibition. In vitro gastrointestinal digestion reduced the ACE inhibitory activity of the M hydrolysate but enhanced its transport across Caco-2 cell monolayers. The transported peptides were found to contain 3-4 amino acid residues showing strong ACE inhibition. The novel ACE inhibitory peptide with the highest inhibition was found to be MCS, with an IC50 value of 0.29 μM. Therefore, tilapia mince hydrolyzed by V. halodenitrificans proteinases contained ACE inhibitory peptides that are potentially bioavailable.