It is a dark-colored liquid that adds a meatlike and salty flavor as well as color to food. It is made by the hydrolysis of soybeans with or without wheat added.
(a) Japanese Shoyu: The molds A. oryzae or A. soyae are involved in fermentation. The yeasts Saccharomyces rouxii, Torulopsis versatile, or T. etchellsii are also involved. Salted cooked soybeans are mixed with ground roasted wheat and the mixture is inoculated with A. oryzae seed culture. Pure cultures of Pediococcus soyae and S. rouxii are added at the start and again one month later. Fermentation proceeds at ambient temperature for a period of up to 3 years. Filtration, pasteurization, and bottling are then carried out (Yokotsuka 1977); (b) Korean soy sauce Kanjang: Molds of the genera Aspergillus, Mucor, Penicillium, Rhizopus, and Sco-pulariopsis are involved in brine fermentation (Lee and Cho 1971). The bacteria Bacillus subtilis, B. pumilis, and L. mesenteroides, and the yeasts Rhodotorula flava, S. rouxii, and Torulopsis dattila are also present. Steamed soybeans are crushed and left to mold without addition of inoculum. Fermentation is allowed to proceed for a couple of weeks, before filtration, pasteurization, and bottling (Lee and Cho 1971); (c) Chinese jiang: Molds of the Aspergillus type overgrow soaked, steamed soybeans coated with wheat flour. Fermentation is carried out at high temperatures and in the presence of salt brine; (d) Malaysian soy sauce Kicap: Soybeans are boiled, mixed with wheat flour, spread on bamboo trays to allow fungal growth without addition of inoculum, transferred to earthenware jars, covered with salt brine and incubated in the sun. After 3 months of fermentation, the sauce can be extracted. Brine can be added to the remaining mash for further extractions. Sugar, molasses, caramel, monosodium glutamate, and benzoic acid may be added to the sauce. A. oryzae, A. soyae, A. nigar, A. flavus, Rhizopus sp., and Pencillium sp. are involved in solid-substrate fermentation in soy sauce factories (Ong 1977); (e) Indonesian soy sauce Kecap: The molds Aspergillus and Rhizopus spp. and various yeasts are involved in fermentation (Poesponegoro and Tanuwidjaja 1977).
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