8.4. The Orient
The characteristic aroma and flavour of soy sauce is due to the enzymatic activities of yeasts, Tetragenococcus halophilus and some Lactobacillus species. Soy sauce (or shoyu) is a condiment widely used in the cooking and seasoning of Japanese food. There are five main types of soy sauce in Japan, each with its own distinctive colour, flavour and use (Fukushima, 1979). In general, the pH of the sauce is within the range pH 4.6–4.8 and the characteristical ly high salt concentration is 17–19%. Concentrations of salt less than 16% can result in the development of putrefactive species during fermentation and ageing and levels greater than 19% interfere with the growth of halophilic bacteria such as P. halophilus and osmophilic yeast such as Zygosaccharomyces rouxii (Beuchat, 1997).