Quality of Filleted Atlantic Mackerel (Scomber Scombrus) During Chilled and Frozen Storage: Changes in Lipids, Vitamin D, Proteins, and Small Metabolites, including Biogenic Amines

Quality changes of vacuum-packed Atlantic mackerel (Scomber scombrus) fillets during 12\ua0months’ frozen storage at −27\ub0C and 9\ua0days’ chilled storage at +4\ub0C were evaluated. Freezing at −27\ub0C preserved the long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), both in light and dark muscle, vitamin D, and the low molecular weight metabolites (LMW) (studied by high resolution nuclear magnetic resonance spectroscopy, HR NMR). Protein oxidation took place, especially between 1 and 7\ua0months, decreasing water holding capacity and protein extractability. During chilled storage, no lipid or protein oxidation was observed, but lipolysis increased, and several LMW metabolites relevant for sensory and nutritional quality degraded into non-favorable compounds. The content of biogenic amines was high at day 9 (e.g., 18\ua0mg histamine/100\ua0g), jeopardizing safety. Preservation of mackerel fillets by freezing at −27\ub0C is thus a better option compared to prolonged chilled storage at +4\ub0C; the quality was well preserved for 12\ua0months’ frozen storage