Calcium carbonate is the same mineral that makes up chalk, limestone and eggshells. For food it is either ground from very pure limestone or precipitated chemically to give a fine white powder. INS 170 covers calcium carbonates: sub-index (i) names calcium carbonate itself, while 170 (ii) is calcium hydrogen carbonate. In the EU it is E170.
Codex gives it an unusually long list of functions: acidity regulator, anticaking agent, surface colour, firming agent, flour treatment agent and stabilizer. In baked snacks it is mostly used as a mild alkali and dough conditioner. On SeekSnack it is listed among the food additives of Fashion Food’s Paprika Flavoured Cracker and Tomato Flavoured Cracker, and as a stabilizing agent in Chocobi Corn Snacks - Chocolate.
