Science Fair Project Encyclopedia
Tofu with soy sauce and a decorative carrot slice
|Chinese characters||豆腐 or 荳腐|
|Quốc Ngữ||đậu hũ|
Tofu (also called bean curd, doufu or beancurd) is a food made by coagulating soy milk with calcium sulfate (gypsum), nigari (a sea-salt derived compound rich in magnesium chloride), or other agents, and then pressing into blocks, similar to the way cheese is made from milk.
Origin and distribution
Tofu was first made in China in the second century BC, during the Han dynasty. It was introduced into Japan in the Nara period (late seventh century). Tofu has become a staple in these countries, as well as Vietnam, Thailand, and Korea.
In the West, tofu was very little known before the middle of the twentieth century, but cultural contact along with increased interest in vegetarianism and healthier foods in general led to the widespread familiarity by the end of that century. In the West today, tofu can be found in Asian markets, farmers' markets, and health food stores, although many large grocery stores also stock it. In Chinese supermarkets, tofu can be found in four to five different grades of firmness and consistency. In the United States market, the largest provider of tofu products is Hong Kong-based Vitasoy International Holdings Ltd., who sell their tofu products under the trademarks VITASOY, Nasoya and Azumaya.
Varieties and uses
In Asian cuisine, tofu can be prepared either in savory or sweet dishes, and is known for absorbing the flavors of the other ingredients used. In the Americas and Europe, tofu is frequently associated with vegetarianism, veganism and imitation meats as it is a good source of protein. However, its uses extend far beyond that. It usually comes packed in water, and comes in two main varieties:
- Hard/firm tofu (木綿豆腐, momendōfu in Japanese, lit. cotton tofu), which has a firm texture resembling cheese
- Soft/silken tofu (絹漉し豆腐, kinugoshi tōfu in Japanese, lit. silk-filtered tofu), which has a custard-like texture
Generally, the firmer style is used for kebabs, mock meats, and dishes requiring a consistency that holds together, while the softer style can be used for desserts, soups, shakes, and sauces.
The extra firm variety of tofu is often called dried tofu (荳乾) because of its low water content, though it is not completely dry. One variety of dried tofu is sliced into long strings with a cross section smaller than 2mm×2mm. This shredded dried tofu (荳乾絲) is usually served cold like noodles, similar to aburaage (油揚).
At the other extreme, the extra soft tofu can be served as a Chinese dessert called doufuhua (Chinese: 豆腐花, literally: tofu flower, d˛ufuhuā 豆腐花 n. jellied beancurd), which is more commonly known as douhua (豆花). In Taiwan, douhua is served with toppings like boiled peanuts, azuki beans, cooked oatmeal, tapioca, mung beans and a syrup flavored with ginger or almond. During the summer, douhua is served with crushed ice; in the winter, it is served warm.
Fresh tofu has a sweet fragrance of soy. Tofu can be easily spoiled if not refrigerated properly during transportation; any trace of sour odor or taste is a tell-tale sign of staleness . Smaller supermarkets tend to sell sour tofu because some don't use refrigerated trucks for delivery like the bigger chain stores. Once purchased, unpackaged tofu should be kept in the refrigerator, in water that is changed once a day. Tofu in sealed packages can be kept for weeks in a refrigerator.
Tofu is very high in protein and has very little flavor of its own. This is what makes it versatile; it takes its flavor from whatever is added to it — marinating is a popular way of flavoring tofu. Tofu can be made to taste like cheese, pudding, eggs, bacon, etc. Furthermore, the texture of tofu can be altered to match the above dishes. Tofu's texture is altered by draining, freezing, pureeing , and cooking. A common lunch in the summer months is namadōfu (生豆腐). This is just fresh tofu served with freshly grated ginger and soy sauce.
One can also purchase flavored tofu, fried tofu, or dried tofu. One famous Chinese delicacy is stinky tofu (Chinese:臭豆腐, literally: stinky tofu), which is fermented and smells like a strong cheese or rotten eggs. Also tofu is made with peanuts jimamami-dōfu (落花生豆腐), or almonds in China, and is also made with coconuts in Indonesia.
Tofu that is freeze dried in freezing weather is called Kōyadofu (高野豆腐). Freeze-dried tofu is excellent for camping, in that it takes up very little room, and makes a very filling nutritious meal on the road.
Tofu can be fried in vegetable oil, sunflower oil and canola oil to varied results. It is often said to taste like a plain doughnut. After thawing,and pressing not only will it hold together on a barbeque grill, but the texture is more like "chicken breast".
During the production of tofu, a thickened membrane coagulates on top of the soy cream. The yellowish membranes are collected and dried in sheet form known as tofu skin or yuba (腐皮) or in bunched up stick form known as tofu bamboo or in Japanese kusatake (腐竹). Tofu bamboos are often used in lamb stew or in a dessert soup. Tofu skins are often used as wrappers in dim sum, or inarizushi (稲荷寿司) (but this uses actual puffed stuffed fried tofu). This product is great to take along camping. A small bag will last many days of quality protein. Okara (雪花菜) is the milk after making the tofu.
- The book Tofu Hyakuchin (豆腐百珍) published in the Edo period lists 100 recipes for cooking tofu.
Tofu related products
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