Formation of 4‐hydroxynonenal (4‐HNE) in frozen mackerel (Scomber scombrus) in the presence and absence of green tea

Abstract BACKGROUND: Aldehydes are secondary lipid oxidation products formed during processing and storage of food. 4‐Hydroxynonenal (4‐HNE) is a major toxic lipid peroxidation product which has been extensively investigated in the clinical field but less so in food products. The aim of the present study was to investigate the formation of aldehydes in stored frozen fish (Atlantic mackerel, Scomber scombrus) with and without antioxidant (green tea). RESULTS: The presence of 4‐HNE in frozen fish was detected for the first time. 4‐HNE was extracted from frozen fish and identified using high‐performance liquid chromatography and liquid chromatography/mass spectrometry. The amount of 4‐HNE increased throughout storage for 26 weeks at − 10 °C in the absence of antioxidant. A significant decrease was observed in fish samples stored at −10 °C with green tea. Minimal amounts of 4‐HNE were formed in fish stored at −80 °C. A similar increase in 4‐HNE was found for methyl linoleate and extracted fish oil exposed to UV irradiation. CONCLUSION: The toxic aldehyde 4‐HNE can be formed in badly stored frozen mackerel and is an indicator of reduced texture quality and nutritional value of fish. Addition of instant whole green tea as an antioxidant can provide a cheap and effective way of enhancing safety, especially in developing countries. Copyright © 2008 Society of Chemical Industry