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Myo-inositol his-, tris-, tetrakis-, pentakis-and hexakisphosphates (IP2-6) were quantified in nine thermally processed or fermented food products. Total inositol phosphate content (mmol/kg dry weight) ranged from 1.35 in white bread to 23.26 in tofu and 26.05 in soy isolate. In all foods analyzed, inositol hexalcisphosphate (phytic acid) accounted for more than 40% of the total inositol phosphates on a molar basis.Step-gradient ion exchange and' ferric chloride precipitation methods for phytate determination were evaluated with a soy isolate sample to which inositol phosphates or adenosine triphosphate (ATP) had been added individually. Both methods measured all of the inositol phosphates, while the former also measured ATP.

Small white potatoes were heated with microwave energy followed by boiling water to determine the penetration of heat, inactivation of peroxidase and firmness of the potatoes.

An ion chromatographic method to determine phytic acid in foods, which allows for the direct injection of extracts into the column without need of a prepurification step, was developed. Infant formula powder, soy flour, soy isolate, wheat bran, and wheat bread were analyzed using the new ion chromatographic method and an ion exchange method. Phytic acid determined with the ion chromatographic method ranged from 0.2% for infant formula powder to 3.28% for wheat bran. The generally lower values found using the ion chromatographic method compared to the ion exchange method are attributed to the measurement of interfering substances such as breakdown products of phytic acid by the ion exchange procedure.