Effects of raw material (chilled/defrosted) and long-term frozen storage on volatile compounds and quality markers of mechanically separated common carp (Cyprinus carpio)

Abstract This study evaluated the impact of raw material thermal history (chilled vs. defrosted) and 12-month frozen storage (-18 °C) on the quality of mechanically separated common carp (Cyprinus carpio). Between months 6 and 12, a significant increase in volatile concentrations – primarily hexanal - and thiobarbituric acid reactive substances (TBARS) was observed, alongside a decrease in total volatile basic nitrogen (TVBN). Microbiological quality remained stable throughout the period and none of the monitored pathogenic species (E. coli, C. perfringens and Salmonella spp.) were detected. Histamine was the dominant biogenic amine, but its levels (7-34 mg/kg) were well below the safety limits. These results suggest that chilled and defrosted raw materials provide mechanically separated fish of similar quality, and the product is shelf-stable for at least six months.