Japanese Soy Sauce

Most of the soy sauce sold in the West is made in Japan or in the Japanese style, which is summarized in the box. During the initial brief fermentation, the Aspergillus mold produces enzymes that will break down wheat starch into sugars, wheat and soy proteins into amino acids, and seed oils into fatty acids. Then during the longer main fermentation, these enzymes do their work; yeasts produce alcohol and a range of taste and aroma compounds; and bacteria produce lactic, acetic, and other acids, and yet other aromas. Over time, the various enzymes and microbial products also react with each other, the sugars and amino acids forming roasty-smelling pyrazines, acids and alcohols combining to form fruity esters. The high-temperature pasteurization develops yet another layer of flavor by encouraging browning reactions between amino acids and sugars. The result is a liquid that’s salty, tart, sweet, savory (from a high concentration of amino acids, mainly glutamic acid), with a rich aroma. Several hundred aroma molecules have been identified in soy sauce, with roasty compounds (furanones and pyrazines), sweet maltol, and a number of meaty sulfur compounds among the more prominent. All in all, soy sauce is a concentrated, mouth-filling liquid, a versatile flavor enhancer for other foods.