Separative Determination of Ortho-and Polyphosphates in Processed Cheese, Ham and Sausage

Abstract

Determination method of various phosphates in food was developed. Five grams of sample were homogenized with 25ml of ice-cold 20% trichloroacetic acid(TCA)solution while cooling and centrifuged. Precipitate was extracted again with 20ml of TCA solution. Supernatants were mixed and made up to 50ml, One ml of the extracted solution was diluted with 300ml of 5mM EDTA·2Na-EDTA·4Na solution(pH 5.0)and the pH was adjusted to 5.0 with 1N NaOH, This solution was poured into anion exchange column(Dowex AG 1×4, 100-200mesh, chloride form, 1×60cm)and the column was washed with 100ml of the above 5mM EDTA solution. The ortho-, pyro-, tri-, and another poly-phosphates were separatively eluted with 200ml of 0.15, 0.26, and 0.38M KCI in 5 mM EDTA solution, and 100ml of 2N HCI solution. Eluted polyphosphates were hydrolyzed by heating with 5N HClO⁴, and reacted with 5% ammonium molybdate. Phospho-molybdate complex was extracted with n-butylacetate and absorbance at the wavelength of 310nm was measured. Total phosphate contents of 7 kinds of processed cheese samples were 1.21-2.20% and polyphosphate contents were 0.21-1.31%. Total and polyphosphate contents of 1 kind of ham and 6 kinds of sausage samples were 0.31-0.75% and 0.16-0.44%, respectively.