Pressing and Refining
Pressing Soy Sauce from Moromi
Soy sauce is pressed from aged moromi. During pressing, moromi is poured into special equipment wherein the mash is strained through layers of fabric, with each layer folded into three sub-layers. After allowing the soy sauce to flow out of the moromi under the force of gravity, the moromi is then mechanically pressed slowly and steadily for about ten hours. It takes a considerable period of time to gradually press the mash in order to produce beautifully clear soy sauce.
Pasteurization to Adjust Color, Flavor and Aroma
Soy sauce pressed from moromi is called “raw soy sauce.” The Kikkoman plant is filled with a sweet scent resembling fresh fruit: this is the aroma of raw soy sauce. Raw soy sauce is left in a clarifier tank for three or four days to separate into its various components, with oil floating to the surface and sediment settling on the bottom. The clarified soy sauce is then run through a steam pipe to heat it: the main purpose is to pasteurize the soy sauce, but this process also halts the activity of the enzymes in order to stabilize the quality of the soy sauce. It also serves to adjust color, flavor and aroma.
Reuse
During the pressing and clarifying processes, cake and oil are generated as by-products. Both of these resources are reused: the cake for livestock feed, the oil as fuel for machinery operations.
