IN-VITRO HYDROLYSIS OF PHYTATE AT 95-DEGREES-C AND THE INFLUENCE OF METAL-ION ON THE RATE

The in vitro hydrolysis of phytate at 95-degrees-C across the pH range 1-12 is reported. The reaction is slow. The first order rate constant varied from 3.98 x 10(-4) min-1 at pH 1 to 0.28 x 10(-4) min-1 at pH 12 with a maximal value of 8.74 x 10(-4) min-1 at pH 4. The reaction is very similar in rate and profile to that of a phosphoric acid ester anion, [(RO)PO3H]-. The 12 metal ions tested had little influence on the hydrolysis reaction although the phytate; metal ion ratio was necessarily high because of the insolubility of phytate metal salts at lower ratios.