Hypochlorite inactivation kinetics of Listeria monocytogenes in phosphate buffer

The inactivation kinetics of Listeria monocytogenes in a phosphate buffer (PB) was determined at different hypochlorite concentrations, pH values and temperatures. D-values, using a linear regression, of L. monocytogenes in PB (pH 6.5) were 23.54, 17.40, 14.24 and 12.00s at 5, 10, 50 and 100 mg l(-1) hypochlorite, respectively, at 30 degrees C. The k-values ranged from 0.098 to 0.192s(-1) and 0.007 to 0.018s(-1) for hypochlorite concentrations (from 5 to 100 mg l(-1)) in PB (pH 6.5) and PB containing 0.1% peptone (pH 6.5), respectively, at 30 degrees C. D-values of L. monocytogenes exposed to hypochlorite were decreased with decreasing pH of PB (pH from 8.5 to 4.5). Hypochlorite showed higher antimicrobial activity at higher temperature. Not only the effect of hypochlorite concentration on the inactivation of L. monocytogenes but also other parameters like temperature, pH and suspending solutions effect the inactivation rates.