On the Thermal Decomposition of Trimethylamine Oxide in Muscle of Some Marine Animals

Abstract

The rate of thermal decomposition of TMAO in muscle of different species of marine animals was investigated. The results obtained were summarized as follows.
1. The rate of thermal decomposition of TMAO varied widely with the species of marine animals, and was generally small in so called white-fleshed fish and considerably high in red-fleshed fish,
2. The ratios of DMA-N to total decomposed products (DMA-N+TMA-N) were high in mollusks, medium in ordinary muscle, and relatively low in dark muscle of fish.
3. When the pH of fish muscle was adjusted by addition of some agents it was observed that TMAO was more rapidly decomposed at the lower pH of muscle. But among different species of fish, even at the same pH, remarkable variations in the rate of decomposition of TMAO were found.
4. Hemoprotein accelerated most effectively the thermal decomposition of TMAO. In the presence of hemoglobin at a high concentration such as 0.5%, TMA was dominant among the thermal decomposition products of TMAO.
5. Though amino acids generally had little accelerating effect on the decomposition of TMAO, cysteine had a significant effect.
6. The thermal decomposition of TMAO proceeded even at temperature lower than 100°C. The lowest temperature seem to be 55-60°C.