Research Description:

Soy sauce is a popular seasoning in Asia and throughout the world, made of fermented soybean. It is produced through a two-step fermentation process, called koji (solid-state fermentation) and moromi (brine fermentation). High NaCl content during moromi fermentation is important for the flavor development and to inhibit the growth of putrefactive and pathogenic microbes. Meanwhile, high NaCl content contributes to excessive sodium intake, which can increase risk of cardiovascular diseases and renal dysfunction. Therefore, producing low-salt soy sauce without compromising its quality and safety has become a challenge for the soy sauce industry. One strategy has been developed to preserve the aroma profile in low-salt soy sauce, by adding T. halophilus and Z. rouxii sequentially. However, the consequence of salt reduction on the safety aspect has not been assessed yet. The aim of this study is to examine the effect of NaCl concentration, temperature, pH, inoculum size, and the sequential addition of T. halophilus and Z. rouxii on the survival of two potential foodborne pathogens, Escherichia coli O157:H7 and Staphylococcus aureus, during reduced-salt moromi fermentation. Knowledge on the survival of both microbes can provide methods for low-salt soy sauce production without compromising its safety.