Formation of trimethylamine in Pacific saury muscle during frozen storage

Abstract

  Trimethylamine-N-oxide (TMAO) content of Pacific saury caught on the high seas in the northwest Pacific Ocean was estimated and its degradation products, trimethylamine (TMA) and dimethylamine (DMA) responsible for characteristic ‘fishy’ odor, were also analyzed during postmortem storage in the frozen state. The TMAO content differed between individual fish and tended to be high in the fish with a large coefficient of fatness. The TMAO content was higher in dark muscle than in ordinary muscle. The amount of TMA hardly increased for up to 12 months during frozen storage at −40°C. At −20°C storage, a great increase of TMA was detected in dark muscle though in ordinary muscle it hardly increased 6 months later, suggesting that the ‘fishy’ odor was mainly derived from dark muscle. The amount of formation of DMA was less than that of TMA in both ordinary and dark muscle during frozen storage.