Cream of Tartar - E336 (I)
Cream of Tartar is a common name for the potassium salt (potassium bitartrate or potassium hydrogen tartrate) of tartaric acid. Cream of Tartar crystallizes during storage of wine or grape juice, where it mainly deposites on the bottom of wine barrels.
It is made of a mixture of, hardly soluble in water, salts of tartaric acid, mainly of potassium hydrogen tartrate (empirical formula KC4H5O6) and calcium tartrate (empirical formula CaC4H4O6). With decreasing temperature, the solubility of Cream of Tartar sinks.
E number: E 336 (i)