A third type of coagulant, enzymes, is not yet used commercially but shows potential for producing both firm and "silken" tofu.
Before grilling, firm tofu is usually marinated overnight.
Most dried tofu is sold after it has been fried or stewed by tofu vendors.
The production of tofu from soy milk is similar to the production of cheese from milk.
Most silken and flavored tofus are produced by large factories.
Flavors can be mixed directly into the curdling soy milk while tofu is being produced.
Soft tofu can also be broken up or mashed and mixed with raw ingredients prior to being cooked.
Tofu has become a staple in many countries, including Vietnam, Thailand, and Korea, with subtle regional variations in methods of production, texture, flavor, and usage.
Tofu is relatively high in protein, about 10.7 percent for firm tofu and 5.3 percent for soft "silken" tofu with about 2 percent and 1 percent fat respectively as a percentage of weight.
Fresh tofu is usually bought from local vendors and is sold directly from large bins or pots at street markets.
Tofu's texture can also be altered by freezing, pureeing, and cooking.
Some non-soy products, such as almonds or black beans, are also processed to make tofu.
In Chinese supermarkets, tofu can be found in many different flavors and grades of consistency.
Tofu is made by coagulating soy milk and pressing the resulting curds.
Tofu skin, with its soft yet rubbery texture, is folded or shaped into different forms and cooked further to imitate meat in vegetarian cuisine.
The book Tofu Hyakuchin (????), published during the Edo period, lists 100 recipes for cooking tofu.
Tofu is known to have been a commonly consumed food in China by the second century B.C.E.
Firm tofu can be used for kebabs, mock meats, and dishes requiring a consistency that holds together, while the softer styles can be used for desserts, soups, shakes, and sauces.
In Asian cuisine, tofu is served raw, stewed, stir-fried, in soup, cooked in sauce, or stuffed with fillings.
Tofu production also creates important side products which are used in various cuisines.
Contemporary tofu manufacturers may use a combination of these coagulants to produce a desired texture in the finished tofu.
Pickled tofu is commonly used in small amounts together with its soaking liquid to flavor stir-fried or braised vegetable dishes (particularly leafy green vegetables like water spinach).
Tofu is low in calories, contains beneficial amounts of iron (especially important for women of child-bearing age) and has no saturated fat or cholesterol.
The light, greenish "bean" smell of tofu is much enjoyed in East Asian cuisines and fresh tofu is often eaten plain or simply flavored.
Firmer tofus, such as Asian dry tofu (??) or Western types of tofu, are pressed to remove even more liquid.
In China, tofu is traditionally presented as a food offering when visiting the graves of deceased relatives.
Freeze-dried tofu and frozen tofu are rehydrated and enjoyed in savory soups.
The earliest documented record of tofu in Japan shows that the dish was served as an offering at the Kasuga Shrine in Nara in 1183.
A well-known hot Sichuan preparation using firm Asian tofu is mбpу dтufu (????).
Silken tofu may be used to replace cheese in certain dishes (such as lasagna) or incorporated into Indian-style curries.
Tofu and soy protein can be industrially processed to match the textures and flavors of cheese, pudding, eggs, or bacon.
Tofu and its production technique were introduced into Japan in the Nara period (late eighth century), and spread to other parts of East Asia, where it has become a core ingredient of many cuisines.
Softer tofus are sometimes used as a dairy-free or low-calorie filler, or made into ice cream substitutes.
Tofu skins are often used as wrappers in dim sum.
Other production techniques are employed to create tofus with unique textures and flavors.
The tofu curds are allowed to cool and become firm.
Soft tofu that has been thinly sliced and deep fried, known as aburage in Japan, is commonly blanched, seasoned with soy sauce and mirin and served in dishes such as kitsune udon.
Chinese folklore often attributes important inventions to well-known historical figures; techniques of tofu production probably existed long before this time.
Coagulation of the protein and oil (emulsion) suspended in the boiled soy milk is the most important step in the production of tofu.
Fresh tofu is usually sold completely immersed in water to maintain its moisture.
The most common theory about the origin of tofu origin maintains that it was invented in northern China around 164 B.C.E.
Tofu and beef are braised in a sauce of chili, ginger and fermented bean paste.
Chinese families sometimes make a steamed meatloaf or meatball dish from equal parts of coarsely mashed tofu and ground pork.
Some of these processing techniques probably originated from the need to preserve tofu before the days of refrigeration, or to increase its shelf life and longevity.
The skin can also be bunched up in stick form and dried into something known as "tofu bamboo" (??, f? zhъ in Chinese; phщ chъc in Vietnamese; kusatake, Japanese).
A sour taste in tofu and a slight cloudiness in the liquid around are an indication of bacterial growth and spoilage.
Tofu originated in ancient China, but little else is known about the origins of tofu and its method of production.
Before refrigeration was available in China, tofu was often sold only during the winter time.
Tofu contains soy isoflavones, which can mimic natural human estrogens and may have a variety of beneficial effects when eaten in sufficient quantities.
Cubes of cold, uncooked tofu seasoned with soy sauce, scallions, and ginger, prepared in a manner similar to Japanese hiyayakko, are also enjoyed.
Some health studies have claimed that regular consumption of tofu and soy milk alleviates symptoms of menopause, reduces the risk of osteoporosis, lowers bad cholesterol and helps prevent certain types of cancers.
Some types of dried tofu are pre-seasoned with special blends of spices, so that the tofu may either be called "five spice tofu" (????) or "soy sauce stewed tofu" (????).
Tofu sold by large manufacturers often comes packaged in sealed plastic cartons or tubes, and may be, at most, two weeks old.
Tofu products can be categorized either as fresh tofu, which is produced directly from soy milk, or as processed tofu, which is produced from fresh tofu.
Tofu has very little flavor or smell of its own and can be prepared either in savory or sweet dishes, acting as a complement to the flavors of the other ingredients used.
The finished tofu can then be cut into pieces, flavored or further processed.
The English word "tofu" comes from the Japanese t?fu (??), which derives from the Chinese dтuf? (?? or ??).
Dried tofu is usually not eaten raw, but stewed in a mixture of soy sauce and spices.
Asian firm tofu and "tofu flower" are commonly sold in this manner and are usually no more than a few hours old.
Dried tofu is typically served thinly sliced with chopped green onions or with slices of meat for added flavor.
The curds are processed differently, depending on the form of tofu that is being manufactured.
According to tradition, tofu is the only food soft enough for the spirits (or ghosts), who have long ago lost their chins and jaws, to eat.
Grated firm western tofu is sometimes used in conjunction with TVP (textured vegetable protein) as a meat substitute.
A common cooking technique in many parts of East and Southeast Asia involves deep frying tofu in vegetable oil, sunflower oil, or canola oil.
Some tofu is made by processing non-soy products, such as almonds or black beans.
Many varieties of tofu are available in both Western and Eastern markets.
Different textures result from a difference in pore sizes and other microscopic features in the tofus produced using each coagulant.
Tofu bamboos are often used in lamb stew or in a dessert soup.
During the warmer months, leftover tofu would be spoiled if not consumed within a day.
The primary evidence for this theory lies in the etymological similarity between the Chinese term for Mongolian fermented milk (rufu, which literally means "milk spoiled") and the term doufu or tofu.