Laboratory of Marine Products and Food Science, Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
In relation to the distribution to international markets of Pacific saury Cololabis saira, which is an abundant resource, we investigated methods for inhibiting the degradation of trimethylamine-N-oxide (TMAO) into trimethylamine (TMA), dimethylamine (DMA), and formaldehyde, which cause quality loss and characteristic fish odor. As a result, we identified that TMAO degradation during storage can be inhibited to a large extent by inmersing the Pacific saury in sea ice and storing it at low temperature immediately after harvesting. Moreover, when highly fresh Pacific saury muscle was stored at 5°C under gaseous oxygen, the production of TMA and DMA during storage was inhibited when compared with storage under gaseous nitrogen. Furthermore, when Pacific saury fillets were stored under oxygen for 1 day at 5°C prior to frozen storage at -20°C, the generation of TMAO degradation products was inhibited in dark muscle during the subsequent frozen storage. These results indicate that gaseous oxygen had an inhibitory effect on the degradation of TMAO in the muscle of Pacific saury.