Usukuchi (sample iii)
and koikuchi (sample i) without preservatives decreased the
bacterial population to an undetectable level within 3 and
5 d, respectively. The low-salt soy sauce without preservatives
(sample iv) required 9 d to do so. The cell numbers of
E. coli O157:H7 decreased in all of the type of soy sauce at
18°C, but more slowly than at 30°C. No decrease in E. coli
O157:H7 cell numbers was observed at 4°C. These results
also indicate that salt content and temperature are important
factors that affect determining the antimicrobial activity of
soy sauce against bacteria.