Tofu is a soybean product made by combining soymilk with a coagulant known as "nigari". There are various types of tofu depending on the way it is processed, the most common are described below.
- Firm Tofu
Soybeans are soaked in water and then ground down and cooked. Once filtered, a coagulant is added to the soymilk, then this mixture is poured into a box lined with a piece of cloth (generally bleached cotton cloth or muslin). The box is covered and pressed down on to remove excess liquid. Firm tofu is made using this process. Firm tofu doesn't break apart easily so it is used in a variety of dishes such as simmered dishes, "nabe" (refers to a variety of communal hot-pot meals), deep-fried tofu, stir-fried tofu, and even tofu steak.
- Silken (Soft) Tofu
Silken tofu is made by adding a coagulant to soymilk, creamier than that used for firm tofu, then pressing it into a box until firm. The smooth, enjoyable texture makes it perfect for chilled tofu, boiled tofu, or used in miso soup or simmered dishes. It is even mixed with seasonings and used to coat "aemono" (dressed dishes often made with fresh seasonal vegetables).
- Grilled tofu / Yaki tofu
Grilled tofu is made by pressing down and removing even more liquid from firm tofu and grilling both sides over an open fire to sear. Grilled tofu is even denser than firm tofu, and less likely to crumble. As such, it is often used in nabe hot-pot or simmered dishes.

Grilled tofu / Yaki tofu

Grilled tofu has a high plant-based protein content, gained from its main ingredient of soybeans. Compared to animal-based proteins from meats, tofu is low in both calories and fat, making it ideal for helping to prevent obesity. It also contains dietary fibers, calcium, B vitamins, and other minerals. Firm tofu is condensed, giving it higher protein, dietary fiber, and calcium counts than silken tofu. On the other hand, silken tofu is made directly from soymilk so it contains more water-soluble potassium than firm tofu.

An unopened package of tofu will keep for approximately one week in the refrigerator. However, tofu will lose its flavor by the day, even when refrigerated, so consumption soon after purchase is recommended. Leftover tofu should be placed in a container, submerged fully in water, then sealed and placed in a refrigerator so that it can be kept for 2-3 days. Expiration dates are the same for silken, firm, and grilled tofu.

The Japanese word for tofu contains the kanji character for “decay,” and this might give the impression that tofu is a fermented food. However, this character originates from the Chinese word that means “gelatinous,” so tofu is not actually fermented.