Rapid Measurement of Phytate in Soy Products by Mid-infrared Spectroscopy

ABSTRACT: The rapid measurement of phytate from soybean and its products, such as soy flour, defatted meal, soymilk, and tofu, was investigated using Fourier transfer infrared spectroscopy (FT-IR) with an attenuated total refraction accessory. The phytate, separated from protein by trichloroacetic acid (TCA), was precipitated completely by the addition of calcium, pH > 7.0, even in the presence of TCA. The precipitate was dissolved in citrate buffer (pH 6.0) and then used for infrared measurement. The absorbance at 1070 cm⁻¹ correlated well the phytate content of the each sample. The measurement of phytate can be done rapidly by FT-IR with an ATR accessory and gives reproducible values.