Hathaigan Kokkaew, Supawan Thawornchinsombut and Jae Won Park

DOI: 10.14456/sjst-psu.2016.58

pp. 439 - 347

Abstract

Response surface methodology (RSM) was performed to maximize the mercury (Hg) reduction from yellowfin tuna
(Thunnus albacare) by products protein isolates (YBPI). The optimal condition of Hg reduction (89.3%) was 10.5 mM CaCl
₂
and a Water:YB of 12.9:1, while other variables were fixed at 5 mM citric acid, 60 min incubation, pH 11 and 8,000 x g for 15
min of centrifugation. At these conditions, the significant protein recovery (80.1%) was obtained. Hydrolysates sequentially
hydrolyzed with G6 followed by GN exhibited the highest angiotensin I-converting enzyme (ACE) inhibitory activity than
other enzyme preparations. Fractionated yellowfin tuna by products protein hydrolysate (YBPH) increased in ACE-inhibitory
activity when peptide size decreased. In-vitro gastrointestinal (GI) digestion significantly increased bioactive property. ACEinhibitory activity of YBPH with and without simulated GI digestion significantly increased after incubating against ACE,
demonstrating pro-drug type peptides.

Keywords

• response surface methodology
• commercial enzymes
• pro-drug type peptides
• gastrointestinal digestion