卵白之蛋白質(egg white protein, EWP)分別經Thermolysin、Alcalase、Esperase和Chymotrysin等蛋白酶水解後所得水解物，均具有血管收縮素Ⅰ轉換酵素(ACE)的抑制活性，結果顯示EWP經Thermolysin水解0.5-24 hr所得水解物，具有最高的ACE抑制活性。其次，將EWP-Thermolysin水解物依序以膜分子量限值(MWCO) 10,000、3,000及1,000道耳吞(Da)進行過濾區分，其中以1,000 Da MWCO濾膜過濾所得1 kDa濾液可顯著將抑制50% ACE活性的濃度IC50從54.1降至17.2μg protein/mL，IC50愈低表示其ACE的抑制活性愈高。本研究所使用的膜反應系統經長期運轉安定性的研究得知，可穩定生產上述EWP-Thermolysis水解物達8hr以上。體外模擬胃腸蛋白酶水解1 kDa濾液的結果指出，胃腸蛋白酶對1 kDa濾液的ACE抑制活性沒有顯著的影響(p>0.05)。

Egg white proteins (EWP) were hydrolyzed with four proteolytic enzymes, including Thermolysin, Alcalase, Esperase and Chymotrysin, to produce hydrolysates with angiotensin I-converting enzyme (ACE) inhibitory activity. The result indicated that EWP hydrolyzed for 0.5-24 hr with Thermolysin produced the highest ACE inhibitory activity among the four enzymes. Therefore, EWP-Thermolysin hydrolysate was produced and further fractionated using several membranes with molecular weight cut-off (MWCO) of 10,000, 3,000 and 1,000 daltons, sequentially. The 1 kDa permeate obtained from the hydrolysate treatment using 1,000 daltons MWCO membrane could further reduce its IC50 value from 54.1 to 17.2 μg protein/mL. A lower IC50 value represented higher ACE inhibitory activity. The operation stability study showed that the membrane reactor system could maintain a steady production of EWP-Thermolysin hydrolysate over 8 hr. The gastrointestinal protease in vitro effect on the ACE inhibitory activity of 1 kDa permeate indicated that gastrointestinal proteases have no significant effect (p>0.05) on the ACE inhibitory activity of 1 kDa permeate.