The Characterization of Myoglobin and Myoglobin-Induced Lipid Oxidation in Frigate Mackerel

Abstract

Myoglobin (Mb) was isolated and purified from the dark muscle of Frigate mackerel (Auxis thazard). After ion-exchange chromatography, the purity of Mb reached 91.30%. The molecule weight of Mb was 16 kDa. The results of the thermal and acid–base stability suggested that oxymyoglobin and metmyoglobin denatured rapidly at 70C and kept stable under 20C. The MetMb% was decreasing and the OxyMb% was increasing in oxymyoglobin and metmyoglobin solutions with the rise of pH. Besides, Oxymyoglobin is much more stable at neutral to alkaline pH, while metmyoglobin kept its stability at acidic to neutral pH. Mb is an effective promoter of lipid oxidation, it engaged in the oxidation as participator but not catalyst. The pro-oxidation activity of oxymyoglobin was enhanced with decrease in pH. The pro-oxidation activities were in the order: MetMb > OxyMb > Hemin > Fe2+, which indicated that MetMb was a greater promoter than OxyMb. Practical Applications Frigate mackerel is an important high yield fishes in China, which is rich in myoglobin (Mb) in muscle and contains high proportion of unsaturated fatty acids. So, the discoloration and lipid oxidation of Frigate mackerel are accelerated during storage, which lowers the quality of related products. Relevant research show that discoloration correlates closely with lipid oxidation. This article is aimed at studying the stability of Mb and lipid oxidation of muscles of Frigate mackerel during refrigerated storage. In this way, this work will provide reference and status for the processing and preservation of Frigate mackerel.