Effect of Frozen Storage Temperature on Free and Bound Formaldehyde Content of Cod (Gadus Morhua) Fillets

Abstract

Samples from the same lot of commercially harvested and processed Northern Bank cod (Gadus morhua) fillets were frozen stored at −30°C, −22°C, −15°C, −12°C, and a simulated industrial fluctuating temperature program for ca. 90 days. Perchloric acid extracts of the frozen premium grade fillets were used for the determination of free formaldehyde (HCHO) and dimethylamine (DMA). Both the formaldehyde dehydrogenase (EC1.2.1.46) enzyme and the Cochin and Axelrod (1959) modification of the colorimetric Nash (1953) method were used to compare the free HCHO content of the extracts. The enzyme procedure consistently detected 21% less HCHO in the fillets during the course of the study. Initial appearance of bound HCHO in the fillets, determined as the difference between DMA and enzymatically or colorimetrically assayed free HCHO, was influenced by frozen storage temperature. The lower concentration of HCHO detected by the enzyme method greatly influenced both the free HCHO concentration and the initial appearance of bound HCHO in the fillets. First‐order reaction rates for free HCHO and DMA were higher at −12°C (p 0.05) than those at −15°C, −22°C, or −30°C but lower than that of the fluctuating temperature conditions. Results also show that both the ratio of DMA and HCHO formation and the ratio of mean DMA and HCHO concentrations were > 1. A more accurate determination of free HCHO in frozen stored fish muscle could provide a better understanding of the role of bound HCHO in textural deterioration.

Protein denaturation in frozen stored hake (Merluccius merluccius L.) muscle: The role of formaldehyde

“…lysosomes). Raising the temperature of storage even for short periods of time, regardless of subsequent reduction of temperature, promotes diffusion and redistribution of reactants and metabolites, facilitating the occurrence of deteriorative reactions (LeBlanc & LeBlanc, 1988). This could explain the fact that insolubility increases gradually during frozen storage and bound FA also increases gradually.…”