Abstract: In order to investigate the effect of lysine-galactose (Lys-Gal) mixture on the thermal decomposition of trimethylamine N-oxide (TMAO) and consequently provide a theoretical basis for controlling the degradation of TMAO, we established an in vitro TMAO-Fe (II) model system and studied the mechanism of action of Lys-Gal on the thermal decomposition of TMAO by differential scanning calorimetry (DSC). The results showed that Lys, Gal and Lys-Gal had a promoting effect on TMAO degradation. Under the conditions of higher reaction temperature, longer reaction time and higher concentration ratio, Lys-Gal was more effective in this regard, generating significantly more formaldehyde, dimethylamine and trimethyl. The DSC curve of TMAO thermal decomposition in the Lys-Gal-TMAO-Fe (II) system showed the most significant change along with three endothermic peaks compared to two endothermic peaks with the addition of either Lys or Gal, and the thermal decomposition temperature was lower, promoting the thermal decomposition of TMAO. This effect of Lys-Gal might be related to its ability to reduce the thermal decomposition temperature of TMAO.

Key words: trimethylamine N-oxide degradation; model system; thermal decomposition; formaldehyde; differential scanning calorimetry