Production of Angiotensin I-converting Enzyme Inhibitor Derived from Egg White Protein Hydrolysates Using a Membrane Reactor
Wen-Dee Chiang1, May-June Tsou2, Chien-Hui Weng1 and Tsun-Chung Tsai1*
1. Department of Food Science, Tunghai University, 181, Sec. 3, Taichung Port Rd., Situn District, Taichung City 407, Taiwan (R.O.C.)
2. Department of Nutrition and Health Science, Chungchou Institute of Technology, 6, Lane 2, Sec. 3, Shanjiao Rd., Yuanlin Township, Changhua County 510, Taiwan (R.O.C.)
(Received: April 27, 2007; Accepted: July 12, 2007)
ABSTRACT
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.
Key words: egg white proteins, ACE inhibitor, hydrolysate, peptide, membrane reactor