Orthophosphoric acid has three functional OH groups attached to P and is a good chelating agent. The phosphate molecules may be condensed in anhydride linkage after loss of water to form linear or cyclic polymers. The examples of these polymers are pyrophosphoric acid, tripolyphosphoric acid, trimetaphosphoric acid, and tetrametaphosphoric acid. The availability of minerals is improved by autoclaving the protein or by supplementation with ethylenediaminetetraacetic acid and some other chelating agents. E. Winterstein in 1897 extracted phytic acid from mustard seeds which yielded inositol and orthophosphoric acid on hydrolysis. Phytic acid is largely blamed for complexing dietary essential minerals in cereals and oilseeds and render them poorly available to monogastric animals. Phytate-protein complexes also play some role in this. A specific method for the estimation of phytic acid is lacking. Formation of phytic acid complexes with proteins is well established and the mechanism of the reaction is pH dependent.