title: Rapid measurement of phytate in raw soymilk by mid-infrared spectroscopy.
abstract: The phytate content in soymilk is known to affect tofu curdling. A rapid measurement of phytate from a water extract of soybean (raw soymilk) in an early stage of tofu processing was investigated using mid-infrared spectroscopy (IR) with an ATR accessory. IR absorption of phytate was observed from 1200 cm-1 to 900 cm-1, and saccharide and protein in the extract also had IR absorption in the same region. In order to separate phytate from other components, the phytate was precipitated completely by the addition of calcium under alkaline condition (pH 11.5). The precipitate was dissolved in citrate buffer (pH 6.0) and then used for IR measurement. The absorbance at 1070 cm-1 correlated well with the phytate content of the soymilk. The measurement of phytate in raw soymilk can be done rapidly by FT-IR measurement with an ATR accessory and gives reproducible values, which can be used for the measurement of phytate content in various soybeans for tofu making.
authors.affiliation: Graduate School of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ishiguro
authors.forename: Tomotada
authors.initials: T
authors.lastname: Ono
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Nakasato
authors.forename: Chigen
authors.initials: C
authors.lastname: Tsukamoto
authors.forename: Shinji
authors.initials: S
authors.lastname: Shimada
mesh_terms: D005504:Food Analysis / Q000379:methods; D005511:Food Handling; D010833:Phytic Acid / Q000032:analysis*; D010936:Plant Extracts / Q000032:analysis; D013025:Glycine max / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D010936:Plant Extracts; D010833:Phytic Acid