The Effect of Trimethylamine-N-Oxide on Microbial Flora in “Ika-Shiokara”

Abstract

Since no means of sterilization is used throughout the manufacturing process of the salted and ripened squid meat product “Ika-Shiokara, ” the quality of the product depends on its associated microbial flora. In the early stage of “Ika-Shiokara” ripening using 10% salts, viable bacteria occured at a level of about 10⁵%/ml of fluid, and then increased gradually with time. The dominant species of bacteria in “Ika-Shiokara” was Staphylococcus epidermidis, but Staphylococcus aureus which closely resembles S. epidermidis in many respects was not detected in all the stages of ripening process. The result suggests that growth of S. aureus was inhibited by some component of “Ika-Shiokara”. We paid attention to trimethylamine-N-oxide (TMAO) and trimethylamine (TMA) which were the characteristic components derived from squid meat. A high amount of TMAO (500-600mg/100ml) was detected in raw squid and in the early ripening process of “Ika-Shiokara”, and it inhibited the growth of S. aureus at this level of concentration but not of S. epidermidis in the nutrient broth.