Calcium Carbonate
What it does
White colour, anti-caking, firming; calcium source.
How it's made
Mined chalk/limestone.
Calcium carbonate is a white mineral used as a food colour (to whiten and to provide surface colour), as an anti-caking and firming agent, as an acidity regulator, and as a source of calcium for fortification. It is the same compound as chalk, limestone and marble.
Food-grade calcium carbonate is produced either by finely grinding and purifying natural high-quality limestone or marble, or by precipitation. In the precipitated route, limestone is heated to make lime, which is slaked with water and then reacted with carbon dioxide to precipitate very pure, fine particles of calcium carbonate under controlled conditions.
The precipitated or ground material is washed, dried and milled to a fine white powder, with the particle size controlled to suit its use. The precipitated grade is especially pure and uniform, which is why it is favoured for food, whether the job is whitening, adding calcium, or adjusting acidity.
Possible reactions
Generally safe; a calcium supplement.