Tofu skin (Chinese: 腐皮; pinyin: fǔ pí) also known as beancurd sheet, dried beancurd, yuba or bean skin, is a Chinese and Japanese food product made from soybeans. During the boiling of soy milk, in an open shallow pan, a film or skin composed primarily of a soy protein–lipid complex forms on the liquid surface. The films are collected and dried into yellowish sheets known as tofu skin.
Tofu skin may be purchased in fresh or dried form. In the latter case, the tofu skin is rehydrated in water before use. It is often used to wrap dim sum.
Because of its slightly rubbery texture, tofu skin is also manufactured in bunched, folded and wrapped forms that are used as meat substitutes in vegetarian cuisine. Tofu skins can be wrapped and then folded against itself to make dòu baō (Chinese: 豆包, literally "tofu package"). These are often fried to give it a firmer skin before being cooked further.
These are the three basic forms. Each comes in many varieties.
Tofu skin may also be bunched into sticks called dried beancurd stick (Chinese: 腐竹; pinyin: fǔ zhú, lit. tofu bamboo). By bunching fresh tofu skins or rehydrated beancurd skins, then tying it tightly in cloth and stewing it, the bunched tofu skin will retain its tied shape. This bunched tofu skin is then called tofu chicken (Chinese: 豆雞; pinyin: dòu jī; or Chinese: 素雞; pinyin: sù jī). In Thai cooking it is referred to as fawng dtâo-hûu (Thai: ฟองเต้าหู้, lit. foam tofu).
Tofu, also called 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 many 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 has a subtle flavor and can be used in savory and sweet dishes. It is often seasoned or marinated to suit the dish.
Tofu originated in ancient China. Chinese legend ascribes its invention to prince Liu An (Chinese: 劉安 Liú Ān, 179–122 BC). Tofu and its production technique were introduced into Korea and then Japan during the Nara period. It also spread into other parts of East Asia as well. This spread likely 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 Bencao Gangmu.
Tofu has a low calorie count, relatively large amounts of protein, and little fat. It is high in iron and, depending on the coagulant used in manufacturing, may also be high in calcium and/or magnesium.
Skin is the soft outer covering of vertebrates. Other animal coverings such as the arthropod exoskeleton or the seashell have different developmental origin, structure and chemical composition. The adjective cutaneous means "of the skin" (from Latin cutis, skin). In mammals, the skin is the largest organ of the integumentary system made up of multiple layers of ectodermal tissue, and guards the underlying muscles, bones, ligaments and internal organs. Skin of a different nature exists in amphibians, reptiles, and birds. All mammals have some hair on their skin, even marine mammals which appear to be hairless. The skin is one of the most important parts of the body because it interfaces with the environment and is the first line of defense from external factors. For example, the skin plays a key role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, and the production of vitamin D folates. Severely damaged skin may heal by forming scar tissue. This is sometimes discoloured and depigmented. The thickness of skin also varies from location to location on an organism. In humans for example, the skin located under the eyes and around the eyelids is the thinnest skin in the body at 0.5 mm thick, and is one of the first areas to show signs of aging such as "crows feet" and wrinkles. The skin on the palms and the soles of the feet is 4 mm thick and the thickest skin in the body.