Study on enzymatic preparation and in vitro stability of ACE inhibitory peptides from cottonseed protein.

Angiotensin-I-converting enzyme (ACE) inhibitory peptides play an important role in the prevention and treatment of hypertension to improve human health, because of their characteristics of safety, no side effects, and easy absorption. The objective was to prepare ACE inhibitory peptides from cottonseed protein using an appropriate protease (e.g., alcalase, protamex, flavourzyme, papain, and bromelain) under optimum conditions. The single-factor experiment was used to optimize hydrolysis conditions. The hydrolysate was then purified to identify sequences of bioactive peptides, and in vitro digestion and absorption stabilities of the hydrolysate was evaluated. It was found that the cottonseed protein hydrolyzed by protamex (1500 U / g) at pH 8.0 and 55 °C for 5 h resulted in the protein recovery rate of 39.8% and the highest ACE inhibitory activity (93.7%). The cotton protein hydrolysate was then separated into five fractions, in which fraction 4 with the highest inhibitory activity (IC₅₀ = 220.1...