THE EFFECT OF pH VALUE ON THE INACTIVATION TEMPERATURE OF FRUIT OXIDASE

Abstract

The temp. required for the inactivation of the peroxidase of apricots, pears, peaches, prunes, figs, lemon peel, tomato, banana and dates was varied with the pH. Resistance to heat greatest in the range of pH 5 to 7, and decreased with decrease in pH value between pH 5 and 2, and with increase in pH value between pH 8 and 12. At pH 12 and pH 2-2.2 the peroxidase was inactivated at room temp. in 24 hrs. or less. The organic peroxide behaved similarly to the peroxidase between pH 2 and 7. At pH values above pH 8 the organic peroxide failed to give positive tests. There was considerable evidence that the inactivating effect of temp. at any given pH is progressive rather than abrupt.