March 22, 2012

Tofu (1) - what it is and how it is made

"Tofu ("bean curd") is one of the most protean of all foods," says Donald Richie (in A Taste of Japan). You can do more things with it than with any other food and its delicate taste serves as a base for thousands of other flavors. Soy protein is of the highest quality, equal to that of meat and dairy products, but without the cholesterol and saturated fat.

[Kinu-dofu]

On top of that, it is the perfect health food. It is incredibly easy for the body to metabolize this light food. Soy isoflavones possess a myriad of biological properties that can benefit the body. It helps against fatigue and a weak stomach and encourages a clear skin and healthy complexion. People in East Asia believe it also helps them live longer lives. It is not only nutritious (like the soy beans from which it is made), it is also cheap. Tofu is low in calories and rich in protein, calcium, iron and phosphorus.

Tofu originated in China and came to Japan in the 8th century - perhaps brought back by priests for whom it formed a valuable protein-rich addition to the vegetarian diet. There is a record that in 1183 it was offered to the Kasuga Shrine in Nara.

Tofu is made in the following way:
  • Soak soybeans overnight in water
  • Grind them, add water and then boil the mixture (this mixture is called go, soybean puree)
  • Strain it to remove the bean pulp (called okara) - what is left is delicious soy milk
  • Add a coagulating agent, bittern (made from crude salt, contains both magnesium chloride and calcium chloride) or calcium sulfate. This will transform the soymilk into curds and whey. The curds are finally poured into a mold and left to settle.
Depending on the finishing process there are three types of tofu:
  1. Momen(-goshi). "Cotton tofu." The soy milk curd is put into a mold lined with cotton cloth. The mold has holes in the sides and bottom so that the liquid can be pressed out. This leave a firm block of tofu into which the cotton weave has been impressed. This firm type of tofu is used in yudofu and hotpots. Also eaten by itself.
  2. Kinu(-goshi). "Silk tofu." The name is given not because a silk cloth is used instead of a cotton one, but because this type of tofu looks "silky smooth."  It is in fact not drained, so that a larger amount of coagulant remains; it is very soft and breaks easily. Used in soups as miso-shiru.
  3. Yakidofu. Lightly broiled tofu. There is a light brown mottling on the skin. It is firmer than momen and kinu tofu and most often used in hotpots - it is especially popular in sukiyaki.
All three types of tofu are fresh and must be kept under water (also the packs you buy in the supermarket contain water!) and refrigerated, otherwise it will not keep for more than a day. Under water and refrigerated, it should be used within 5 to 7 days of manufacturing.