Manufacturing Process
Cereal grains are particularly rich in phytates; corn steep water produced in the wet milling of corn, is one of the best sources of such material. To recover the phytate from corn steep water it is customary to neutralize the same withan alkaline material, suitably lime, causing the phytate to precipitate as a crude salt which can be removed readily by filtration. This material contains substantial amounts of magnesium, even though lime may have been employed as precipitant, and traces of other metallic ions, as well as some proteinaceous materials and other contaminants from the steep water. It may be partially purified by dissolving in acid and reprecipitating but, nevertheless, such commercial phytates do not represent pure salts. They always contain some magnesium, appreciable amounts of iron and nitrogenous materials, and traces of heavy metals, such as copper.
Heretofore, no economical method for preparing pure phytic acid was known. The classical method was to dissolve calcium phytate in an acid such as hydrochloric acid, and then add a solution of a copper salt, such as copper sulfate to precipitate copper phytate. The latter was suspended in water and treated with hydrogen sulfide, which formed insoluble copper sulfide and released phytic acid to the solution. After removing the copper sulfide by filtration, the filtrate was concentrated to yield phytic acid as a syrup.
The phytic acid in the form of a calcium phytate press cake may however be contacted with a cation exchange resin to replace the calcium with sodium to yield phytate sodium.
