Tofu

Tofu (豆腐, dòufu, literally "bean curd") is a food made by coagulating freshly boiled soy milk and then pressing the resulting curds into solid white blocks. For pressed tofu the process is analogous to cheesemaking: soybeans are the equivalent of milk, and a coagulant—nigari (a solution of magnesium salts) or a slurry of gypsum powder (calcium sulfate)—curdles the soy milk before the mass is shaped and pressed, giving consistencies from silken to extra-firm. Silken tofu is the exception: it is set by a different route that leaves no whey to drain, and its process resembles yogurt rather than cheese manufacture. That comparison concerns only how the product is set in its container; neither yogurt nor silken tofu is made by fermentation.

The production process begins with soaking dried soybeans overnight, then grinding them with water, boiling the mixture, and filtering out the insoluble pulp (okara, 豆渣, dòuzhā) to produce soy milk. The coagulant is stirred into the hot soy milk, causing it to separate into curds and whey. For silken tofu (嫩豆腐, nèn dòufu), the curds are not pressed, resulting in a smooth, custard-like texture. For firm and extra-firm tofu (老豆腐, lǎo dòufu), the curds are pressed under weights to remove more whey, producing a denser, chewier product.

Bean curd has been prepared and eaten in China for thousands of years. An FAO technical overview places a written record of tofu preparation in the second century B.C.; the original document behind that date has not been identified for this page. The invention is traditionally attributed to the Prince of Huainan, Liu An (刘安) of the Western Han. That attribution is recorded in a much later text—the 1596 Compendium of Materia Medica—and the sources cited on this page do not include a record from Liu An's own period. From China, tofu spread to Japan (where it became a cornerstone of Buddhist vegetarian cuisine, shōjin ryōri), Korea, and eventually throughout East and Southeast Asia. As a complete protein containing all essential amino acids, tofu was historically crucial as a source of nutrition in East Asian diets, particularly for Buddhist monks who observed vegetarian dietary precepts. Tofu's mild flavor and adaptability make it a canvas for countless preparations.

The versatility of tofu in East Asian cuisine is extraordinary. Silken tofu is used in soups (like miso soup or hot and sour soup), chilled as a summer appetizer (hiyayakko in Japan, with ginger and soy sauce), or blended into smoothies and desserts. Firm tofu is cut into cubes and stir-fried, deep-fried, braised in savory sauces (mapo tofu, 麻婆豆腐, being the most famous example), or grilled (yaki-dofu). Tofu is also a starting material for related products, and these derivatives should not be confused with tofu itself. Fermented tofu (腐乳, fǔrǔ), also known as "Chinese cheese," is made by ageing tofu in brine with rice wine and spices, and is a genuinely fermented product. Dried tofu skin (腐竹, fǔzhú) is not fermented at all: it is a dried film, lifted from the surface of continuously heated soy milk and then dried into sheets or sticks for stir-fries and hotpots. Nutritionally, tofu is an excellent source of protein, calcium (especially when set with calcium sulfate), iron, and isoflavones, which have been studied for their potential health benefits including reduced risk of heart disease and certain cancers.