Ammonium ferric citrates are a complex mixture of ammonia, iron, and 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 green or reddish brown powder that is very soluble in water. Ferric ammonium citrates are used as an anti-caking agent in salt, and to enrich the iron content in iron-fortified food.http://www.creative-enzymes.com/product/Ferric-Ammonium-Citrate_546.html