For thousands of years, soy sauce has been one of the most popular seasonings in Asian countries including China and Japan (i.e. with an annual production over 7 million tons), and is also
increasingly consumed in the Western world, due to its intense umami taste, characteristic aroma and desirable components, including protein and antioxidants, such as isoflavones and superoxide
dismutase.Three fermentation processes are used globally for producing soy sauce: High-salt liquid-state fermentation soy sauce (HLFSS), low-salt solid-state fermentation soy sauce (LSFSS) and Koikuchi soy sauce (KSS) (as shown in Fig. 1). HLFSS and LSFSS are mainly used in China, while KSS accounts for about 85% of the total soy sauce consumed in Japan. Different fermentation processes employ different raw materials, brine solution concentrations,strains of microorganisms, moromi fermentation time and temperature, which in turn influence the flavour of soy sauce