The flavor problem of soybean oil. XI. Phytic acid as an inactivating agent for trace metals

Abstract

SummaryPhytic acid, a natural constituent of cereal grains and oilseeds, is shown to be highly effective in the control of metallic contamination in edible oils. Phytic acid added to regularly processed edible oils at the 0.01% level has shown a marked improvement in the organoleptic and oxidative stability of these oils.We could not establish whether the mode of action of phytic acid was the result of the direct formation of insoluble phytate salts, or the breakdown of phytic acid with the formation of phosphoric acid which would serve as the active agent. Phytic acid solutions all contained some free phosphoric acid. Most phytic acid samples darkened with age and showed a progressive increase in the amount of free phosphoric acid. To be effective, it was necessary to add phytic acid prior to the deodorization process.Evidence is presented to show that a large part of the synergistic effects of many activators can be explained by metallic inactivation. It is suggested that much of the antioxidant effect observed for rice bran, oat “flour”, and cereal brans could be the result of metal inactivation by the phytic acid present in these materials.