Accurate and Simple Measurement of Phytic Acid Contents in Cereal Grains

Abstract

We developed an accurate and simple method for measuring the phytic acid contents in cereal grains on the basis of close examination of various factors affecting the accuracy and reproducibility of the measurement. Our conclusions were: (1) As extracting medium for phytic acid, HCl was better than trichloroacetic acid or H2SO4. (2) The suitable pH range for extracting phytic acid was 0.3 to 1.0. (3) Complete formation of Fe-phytate required four to nine times as much Fe3$ as phytic acid. (4) No definite effect of Na2SO4 on the recovery of phytic acid was observed, though it increased the extracting efficiency of trichloroacetic acid. (5) The determination limit of phytic acid by the iron precipitation method was 3.3 μmol per 20 ml. Our new method gave reliable results, and a linear relationship of y=0.3163x$0.0597 was obtained up to 0.025 μmol μ−1 between the concentration of phytic acid and the zone length in isotachophoresis. The phytic acid contents of two kinds of rice, two kinds of rye, and one kind of wheat and of barley were determined with this method.