THE EFFECT OF pH VALUE AND HYDROGEN PEROXIDE CONCENTRATION ON FRUIT OXIDASE ACTIVITY

Abstract

The optimum, minimum and maximum pH values for various oxidase indicators in contact with apricot oxidase vary with the indicator; but in general the optimum for most of the indicators used in these studies lies near neutrality. The H2O2 concentration greatly affects the intensity of the oxidase reaction with various indicators, the optimum range of H2O2 conc. in apricot juice low in catalase being 5-25 mgm. of H2O2 per 100 cc. The peroxidase was inactivated at about pH 2.0 and at about 12.8 in less than 3 hrs. and on subsequent adjustment to neutrality failed to respond positively with the usual peroxidase indicators. The organic peroxide was considerably less resistant than the peroxidase to high pH values. In general, in any comparative studies on the activity of fruit oxidase the pH value of the medium and the H2O2 conc. must be carefully controlled and the proper indicator chosen.