EFFECT OF HYDROGEN PEROXIDE CONCENTRATION AND pH ON INACTIVATION KINETICS OF ESCHERICHIA COLI

The inactivation kinetics of Escherichia coli ATCC 35218 in hydrogen peroxide solutions at different concentrations (0-3.00% w/v) and pH values (3.0-7.2) at 25C was studied. Effectiveness of H2O2 solutions against E. coli ATCC 35218 appeared to improve at both higher H2O2 concentrations and more acidic pH values. As the H2O2 level was lowered, the influence of the pH of the solution on the rate of E. coli destruction was more notorious. Most of the inactivation semilogarithmic curves were not linear. Inactivation kinetics was modeled by using a Weibull type distribution of resistances. Quadratic polynomial models were applied to express the effects of H2O2 concentration and pH on the exposure time needed to reduce the microbial population by 5 log.