Haemoglobin-mediated lipid oxidation in the fish muscle: A review

Lipid oxidation is a major cause of quality deterioration in muscle-based foods, where flavour, colour, texture and nutritional value can be negatively affected. The presence of haem pigments and trace amounts of metallic ions makes the fish, especially dark flesh fatty fish, prone to lipid oxidation. In contrast to mammalian meat, haemoglobin (Hb) is a major contributor to lipid oxidation in fish and fish products, since the blood is not practically removed prior to processing. Hb is known as an important catalyst of lipid oxidation in fish muscle. Hb can be a source of activated oxygen due to Hb autoxidation, and haem or iron can be released from the protein to promote lipid oxidation. Autoxidation appears to be a critical step in the ability of haem proteins to stimulate lipid oxidation since metHb reacts with peroxides to stimulate formation of compounds capable of initiating and propagating lipid oxidation. Hb-mediated lipid oxidation can be accelerated by reduction in pH and could be due to enhanced autoxidation of Hb at reduced pH. Hb from different fish is known to promote lipid oxidation in fish muscle differently. Thus, the knowledge regarding the pro-oxidative activity of Hb from different fish species can be useful in developing the species-specific anti-oxidative strategies to retard the lipid oxidation and increase the shelf-life of fish.