| Summary: | 碩士 === 國立海洋大學 === 食品科學系 === 89 === Abstract
The objectives of this research were to study the peptides from skipjack, mackerel and tilapia meat hydrolysates and their antioxidant activity. The skipjack, mackerel and tilapia meat were hydrolyzed by 0.5% and 1% Protease A and Protease N at 50℃ for 0, 5, 10, 15, and 24 hr. The pH value of all fish meat hydrolysates decreased and then increased or decreased gradually during hydrolysis. The NH3 of all hydrolysates increased with the hydrolysis time.
The total free amino acids (FAA) of all fish meat hydrolysates increased significantly during the first 5 hr hydrolysis. The increase rate of Protease A was higher than that Protease N. A high level of anserine (Ans) was found in skipjack meat, but carnosine (Car) was not detected. Both mackerel and tilapia meat had no those histidine-related dipeptides. However, Ans and Car were found in high levels in the enzymatic hrdrolysates of all fish meat. The total combined amino acids (CAA) of all hydrolysates increased significantly during the first 10 hr hydrolysis, and thereafter decreased with the hydrolysis time. The CAA increase rate of Protease N was higher than that of Protease A.
All fish meat hydrolysates possessed the ability to inhibit linoleic acid autoxidation. The Protease N hydrolysate of the same fish meat had a higher ability than Protease A. The reducing power of all hydrolysates increased with the hydrolysis time, and the ability of Protease A hydrolysate was higher than that of Protease N. The skipjack meat hydrolysate with 0.5% Protease N for 5hr hydrolysis had the highest ability of scavenging on α,α-diphenyl-β-picuylhydrazyl free radical. The positive correlation between the antioxidative activity and the levels of Ans, Car, and CAA of the hydrolysate indicated that small peptides might be an important factor influenceing the antioxidative activity.
The HPLC profiles of the hydrolysates using superdex peptide column showed that molecular weight of compounds in the enzymatic hydrolysate was mostly lower than 6000 Da. The inhibition of linoleic acid autioxidation for all gel filtration fraction of the Protease N hydrolysates indicated that the peptides with molecular weight of 500-1700 Da had a stronger antioxidative activity.
In addition to antioxidative activity, the hydrolysates of fish meats were rich in FAA and peptides, which were the taste active components of seafood. The results of this study provided the data for the efficient utilization of fish to produce the natural ingredients with both antioxidant and seasoning functions.
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