Chinese tofu is the separated curd of soy milk, usually formed or pressed into blocks. The phonetic translation and pronunciation is more commonly “doufu.” Elsewhere throughout Asia, where it is similarly named, tofu is so widely prepared and eaten as to be considered a staple food. It is also called bean curd.
Although it can be made with processed soy milk, tofu usually comes from dried soy beans. They are soaked, mashed, and boiled, then strained. After this “milk” is returned to boil, a coagulant is introduced. The most common is gypsum, and other salts. Acids, such as those used to make cheese from animal milk or even the juice of citrus fruits, are also used as an agent to coagulate soy milk.
Coagulation precipitates and separates the solids from the liquid. Quite rapidly, the milk “curdles.” The solid curd particles are strained through a porous cloth such as muslin, and then placed in a square, traditionally wooden, mold. The mold is weighted to squeeze out excess liquid and to compress the curd into a solid block. This process of creating the basic white colored Chinese tofu has remain unchanged since at least 2,000 B.C. and likely longer.
Variations in the process produce different types of tofu. Longer or heavier compression of the brick mold will produce tofu of increasingly more firm texture. Prior to coagulation, other flavors can be mixed with the soy milk to make, for example, a sweet dessert tofu of different color. Soft, so-called silken tofu, which has a smooth custard-like texture, is made by using both salt and acid as the coagulant.
Fresh Chinese tofu does not have a long shelf life. In part to prolong spoilage, but also to vary its texture and flavor, tofu is processed in various ways. It can be dried, to be reconstituted in water; it can be pickled, for better preservation. One of the most exotic delicacies, called “stinky tofu,” is fermented in a mix of vegetables and fish brine. While it is said to be uniquely tasty, its odor is nearly unbearable for most people.
Chinese tofu is prepared in the kitchen in myriad ways, both sweet and savory. Fresh tofu has little flavor or smell, and is therefore versatile, adaptable to any flavor. Deep-fried, the flesh turns light and airy. A spicy dish of China’s Sichuan province called ma po tofu that braises tofu cubes and ground meat to a gravy of hot chili oil and black bean paste has become increasingly popular in Chinese restaurants all over the world. Tofu is also a frequent ingredient of vegetarian diets because, while low in fat and calories, it is especially rich in protein and iron.