1Industrial Research Center of Ehime Prefecture, Matsuyama, Ehime 791-1101, 2Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
The freshness and kamaboko gel-forming ability of shortfin lizard fish Saurida elongata meat rapidly deteriorate during cold storage at 5°C. We found that fish meat stored in that manner contains a large quantity of trimethylamine-N-oxide (TMAO) above 25mmol/kg. TMAO rapidly degrades into formaldehyde and dimethylamine. The amount of formaldehyde increased to high levels at which the kamaboko gel-forming ability was almost lost after 2-3 days' of storage. Shortfin lizard fish meat produced formaldehyde abundantly at the setting temperature of 30°C for 6 hours. Washing with water effectively removed TMAO from minced meat. Deterioration in gel-forming ability was reproduced by addition of formaldehyde to washed shortfin lizard fish meat. In contrast, white croaker Argyrosomus argentatus meat contained over 50mmol/kg of TMAO, but it retained its gel-forming ability well during storage because of its lack of formaldehyde. Adding formaldehyde to washed white croaker meat and shortfin lizard fish meat decreased gel-forming ability.