Calcium citrate is the calcium salt of citric acid, a natural weak organic acid found in many fruits, especially citrus fruits. Commercially it may be produced by the fermentation of carbohydrate solutions, usually molasses or hydrolysed corn starch with Aspergillus niger. This produces a white crystalline powder which is soluble in water. Calcium citrate is used as an acidity regulator, preservative, anti-oxidant, sequestrant, firming agent, and sometimes a flavour in food.http://www.creative-enzymes.com/product/Calcium-Citrate_543.html