Calcium formate (CAS 544-17-2)

Calcium formate is the calcium salt of formic acid. It is also known as E238. Under this E number it is used as an animal feed preservative within EU, but not in foods intended for people. Calcium formate is stable at room temperature, is inflammable and forms orthorhombic crystals. The mineral form is very rare and called formicaite, and is known from a few boron deposits.

Calcium formate is used within EU as an animal feed preservative. It acidifies the feed thus preventing microbe growth and increasing shelf life. About 15 g of calcium formate addition per kg of feed lowers its pH by one. 15 g/kg is the maximum recommended feed concentration within EU – this level is thought to be safe for pigs, chickens, fish and ruminants. The compound is not environmentally harmful in feed use at these levels. Calcium formate prevents the growth bacteria such as E. coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus hirae in growth mediums. It also prevents the growth of fungi like Aspergillus niger and Candida albicans. However, the relevance of these experimental observations to feed preservation is not known.