Bean Curd, or Tofu

Bean curd is curdled soy milk, a concentrated mass of protein and oil formed by coagulating the dissolved proteins with salts that yoke them and the protein-coated oil droplets together. Bean curd was invented in China around 2,000 years ago, was well known by 500 CE, and became a daily food beginning around 1300. Chinese bean curd is traditionally coagulated with calcium sulfate, Japanese bean curd and bean curd from coastal regions of China with what the Japanese call nigari, a mixture of magnesium and calcium salts left over when table salt, sodium chloride, is crystallized from seawater.