| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 103 === Marlin is a popular fish in Taiwan and usually consumed as raw or cooked. In addition, it is also commonly processed and consumed as fish balls and fried floss. At the beginning of fried floss process, marlin fish need to be fully cooked and thus produces a great amount cooking juice which contain but used as animal feed currently. It has been reported that fish protein hydrolysates possess antioxidant activies because contain bio-active peptides. However, marlin cooking juice was never reported. Thus, two proteases, alcalase and protease XXIII, were used to hydrolyze the marlin cooking juice from a local marlin floss manufacture plan. Different hydrolysis time and substrate ratios were tested. Ultrafiltration membranes were used to separate hydrolysates into different ranges of molecular weights, >10 KDa, 5-10 KDa, 1-5 KDa and <1 KDa.
Our results showed the hydrolysates possessed high anti-oxidative activities such as ABTS+, DPPH, superoxide anion, hydroxyl radical scavenging abilities and reducing power. The hydrolysate in the range of 5-10 KDa had the ABTS+ and DPPH, superoxide anion and hydroxyl radical scavenging activities and reducing power in the molecular range of 5-10 KDa, 1-5 KDa and <1 KDa, respectively had the highest. The hydrolysate in the range of >10 KDa and 5-10 KDa contained most amount of peptide. Thus, the hydrolysate in the range of 5-10 KDa was chosen for further purified by ion exchange column chromatography. The purified fractions were collected and peptide concentrations and DPPH radical scavenging activity were analyzed. Resutls of SDS-PAGE showed the unhydrolyzed cooking juice possessing protein bands but not the hydrolyate of both.
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