Separation and identification of ACE inhibitory peptides from cashew nut (Anacardium occidentale Linnaeus) protein

Cashew nut protein powder was hydrolysed by alkaline protease to prepare ACE inhibitory peptides. Results showed that the optimum conditions were: substrate concentration, 7 g/100 mL; amount of enzyme, 3%; pH, 10.5; hydrolysis time, 6 h; and temperature, 45°C. Under these conditions, ACE inhibitory rate was 57.45%. ACE inhibitory peptides were filtered using an ultrafiltration membrane of different molecular weights and Sephadex G-15 gel column. We found that the molecular weight was <3000 Da, and the ACE inhibitory rate concentration was 100 mg/mL. The M₂ component, which was the most active component in ACE inhibitory peptides, yielded an ACE inhibitory rate of 77.58%. The M₂ component contained 18 types of amino acids, including seven types of essential amino acids with the highest proline content reaching 23.56% (P < 0.01). The molecular weight of the M₂ constituent was observed as 389 Da, with an amino acid sequence of Glu- Ser - Arg.