Angiotensin I-converting enzyme inhibitory (ACEI) peptides, released from precursor proteins in vitro and in vivo, have been paid increased attention in the prevention of high blood pressure. In this study, we attempted to prepare novel ACEI peptides from Tieguanyin tea residue protein (TTRP). Different proteases were used to hydrolyze TTRP to prepare ACEI peptides, neutral protease and alkaline protease hydrolysates exhibited higher ACEI activity and was chosen in further hydrolysis treatment. Response surface methodology (RSM) was used to optimize the enzymatic condition, and the results indicated that the optimal conditions of enzymatic hydrolysis were: 4% (W/V) of TTRP in water was hydrolyzed with 3500 U/g neutral protease at 50 ℃ and pH 6.5 for 2.5 h in the first step and then with 5000 U/g alkaline protease at 50 ℃ and pH 10.0 for 3 h in the second step༎Under the optimum condition, the ACE inhibitory rate of the final products was 88.45%±0.45% at the concentration of 1.0 mg/mL. Moreover, ACEI peptides derived from TTRP showed good stability under different temperatures, pHs, metal ions and gastrointestinal digestion. These results indicated that the TTRP has potential to be used for preparing ACEI peptides, providing the basis for improving the utilization efficiency for blood pressure reduction and benefit in economic value.

In this study, we attempted to prepare novel angiotensin I-converting enzyme inhibitory (ACEI) peptides from Tie Guanyin tea residue protein (TTRP). Different proteases were used to hydrolyze TTRP to prepare ACEI peptides, neutral protease and alkaline protease hydrolysates exhibited higher ACEI activity and was chosen in further hydrolysis treatment. Response surface methodology (RSM) was used to optimize the enzymatic condition, and the results indicated that the optimal conditions of enzymatic hydrolysis were: 4% (w/v) of TTRP in water was hydrolyzed with 3500 U/g neutral protease at 50 °C and pH 6.5 for 2.5 h in the first step and then with 5000 U/g alkaline protease at 50 °C and pH 10.0 for 3 h in the second step. Under the optimum condition, the ACE inhibitory rate of the final products was 88.45% ± 0.45% at the concentration of 1.0 mg/mL. Moreover, ACEI peptides derived from TTRP showed good stability under different temperatures, pHs, metal ions and gastrointestinal digestion. These results indicated that the TTRP has potential to be used for preparing ACEI peptides.