Tofu, also known as bean curd, is a food made by coagulating soy milk and then pressing the resulting curds into soft white blocks. It is a component in East Asian and Southeast Asian cuisines. There are many different varieties of tofu, including fresh tofu and tofu that has been processed in some way. Tofu is bought or made to be soft, firm, or extra firm. Tofu has a subtle flavour and can be used in savoury and sweet dishes. It is often seasoned or marinated to suit the dish.
Tofu originated in Han dynasty China some 2,000 years ago. Chinese legend ascribes its invention to prince Liu An (179–122 BC). Tofu and its production technique were introduced into Korea and then Japan during the Nara period (710–794). Some scholars believe tofu arrived in Vietnam during the 10th and 11th century. It spread into parts of Southeast Asia as well. This spread probably coincided with the spread of Buddhism because it is an important source of protein in the vegetarian diet of East Asian Buddhism. Li Shizhen in the Ming Dynasty described a method of making tofu in the Compendium of Materia Medica.
Tofu has a low calorie count and relatively large amounts of protein. It is high in iron, and depending on the coagulants used in manufacturing (e.g. calcium chloride, calcium sulfate, magnesium sulfate), it can have higher calcium or magnesium content.
The term tofu by extension can be used in similarly textured curdled dishes that do not use soy products at all, such as “almond tofu” (almond jelly), tamago-dōfu (egg), goma-dōfu (sesame), or peanut tofu (Chinese 落花生豆腐 luòhuāshēng dòufu and Okinawan jīmāmi-dōfu ).
Tofu is made by coagulating soy milk and pressing the resulting curds. Although pre-made soy milk may be used, some tofu producers begin by making their own soy milk, which is produced by soaking, grinding, boiling and straining dried (or, less commonly, fresh) soybeans.
Coagulation of the protein and oil (emulsion) suspended in the boiled soy milk is the most important step in the production of tofu. This process is accomplished with the aid of coagulants. Two types of coagulants (salts and acids) are used commercially. The third type of coagulant, enzymes, is not yet used commercially but shows potential for producing both firm and “silken” tofu.
Varieties of Tofu
There is a wide variety of tofu available in both Western and Eastern markets. Despite the large variety, tofu products can be split into two main categories: fresh tofu, which is produced directly from soy milk, and processed tofu, which is produced from fresh tofu. Tofu production also creates important side products which are often used in various cuisines.
Depending on the amount of water that is extracted from the tofu curds, fresh tofu can be divided into three main varieties. Fresh tofu is usually sold completely immersed in water to maintain its moisture content.
Soft/silken tofu (嫩豆腐 or 滑豆腐, nèn dòufu or huá dòufu, in Chinese, lit. “soft tofu” or “smooth tofu”; 絹漉し豆腐, kinugoshi tōfu in Japanese, lit. “silk-filtered tofu”; 순두부, 純豆腐, sundubu in Korean, lit. “pure tofu”) is undrained, unpressed tofu that contains the highest moisture content of all fresh tofus. Silken tofu is produced by coagulating soy milk without curdling it. Silken tofu is available in several consistencies, including “soft” and “firm”, but all silken tofu is more delicate than regular firm tofu (pressed tofu) and has different culinary uses. In Japan and Korea, traditional soft tofu is made with seawater. Silken tofu is a versatile, reliable substitute for dairy and eggs, especially for smoothies and baked desserts.
Douhua (豆花, dòuhuā or 豆腐花, dòufuhuā in Chinese), or tofu brain (豆腐腦 or 豆腐脑, dòufunaǒ in Chinese) is often eaten as a dessert, but sometimes salty pickles or hot sauce are added instead. This is a type of soft tofu with an even higher moisture content. Because it is very difficult to pick up with chopsticks, it is generally eaten with a spoon. With the addition of flavourings such as finely chopped spring onions, dried shrimp, soy sauce, chilli sauce, douhua is a popular breakfast dish across China. In Malaysia, douhua is usually served warm with white or dark (palm) sugar syrup, or served cold with longans.
Some variation exists among soft tofus. Black douhua (黑豆花, hēidòuhuā) is a type of silken tofu made from black soybeans, which is usually made into dòuhuā (豆花) rather than firm or dry tofu. The texture of black bean tofu is slightly more gelatinous than regular douhua and the colour is greyish in tone. This type of tofu is eaten for the earthy “black bean taste.” Edamame tofu is a Japanese variety of kinugoshi tōfu made from edamame (fresh green soybeans); it is pale green in colour and often studded with whole edamame.
Most recipes will let you know when silken tofu is needed. We find that there is little difference between firm and extra firm silken tofu, and for most purposes, the different kinds of silken tofu are interchangeable, so don’t worry if your supermarket only stocks one kind.
Salad dressings, sauces and desserts usually use silken tofu for a thick and creamy texture. Silken tofu in an aseptic container has a shelf life of up to a year, unopened. Once opened, submerge any used portion with water in a container, cover, and refrigerate for up to a week.
Silken tofu crumbles very easily. It is not recommended that you press silken tofu; only regular or firm tofu needs to be pressed. Use a gentle hand when carefully slicing silken tofu, as it may otherwise fall apart.
Regular tofu, also called Chinese-style tofu or bean curd is more common than silken tofu and comes in a plastic container in the refrigerator or produce section of most grocery stores. Firm or extra firm regular tofu is best used in stir fries, tofu bakes or any dish where you will want the tofu to retain its shape. For recipes that call for crumbled or mashed tofu, such as mock ricotta or scrambled tofu, firm tofu will work just fine, though medium or soft tofu will have a smoother consistency.
Cooking with Tofu
When cooking with firm tofu, you will usually want to drain and press the tofu first, and some recipes will tell you to freeze and thaw your tofu.
How to Press or Drain Tofu
Many of the recipes you’ll find call for pressed tofu. This simple process removes excess moisture, allowing more flavour to be absorbed while cooking.
- Layer your cutting board or bowl with two layers of towels and place tofu on towels.
- Place tofu on board or in bowl.
- Lay a fresh towel on top of tofu.
- Gently press down on towel to remove any initial water.
- Remove damp towel and place two layers of fresh towels on top of tofu.
- Carefully place a bowl or other weight on top of towels to press down on tofu.
- Let sit for at least fifteen minutes.