Nigari is a salt coagulant used in the making of tofu. They help create a smooth, tender texture. In Japan, a white powder called nigari, which consists primarily of magnesium chloride, is produced from seawater after the sodium chloride is removed and the water is evaporated. Depending on the production method, Nigari may also contain small quantities of magnesium sulfate, potassium chloride, calcium chloride and trace amounts of other naturally occurring slats. There is no perceivable taste from this in the finished tofu.