Abstract: The Phytic acid(PA) could protect L - ascorbic acid(L - ASA) at pH3. 5 ~ 10. 0. In neutral solution, PA inhibited the metal ions to catalytic action of oxidation of L - ASA significantly, but the inhibiting effect decreased when citric acid is added. Moreover, PA could lower the oxidative action of H2O2 to L -ASA when metal ions existed. In orange juice(pH<3. 5), PA showed little protective effect on L - ASA.

Key words: Phytic acid Sodium phytate Storag Ascorbic acid Protective effect