Peracetic acid (PAA) is a powerful sanitizer used by food industries all over the world. The main disadvantage of PAA is its decomposition rate. The main purpose of this paper is to study the decomposition of PAA between 20 and 40 °C with 0.0, 2.5 or 5.0 g•L-1 of beer, milk or tomato juice in its solutions. The observed decomposition of PAA is a first-order reaction for solutions free of organic matter with observed rate constants from 1.24•10-3 to 5.59•10-3•h-1 and an activation energy (Ea) of 62.11 kJ•mol-1. However a pseudo first-order reaction was observed in the presence of organic matter and the rate constants between 1.13•10-3 and 2.18•10-2 h-1. The Ea calculated by the observed decomposition rate constants are 42.3 and 61.2 kJ•mol-1 when there was 2.5 and 5.0 g/L beer in solution, respectively. PAA solutions contaminated with 2.5 and 5.0 g•L-1 milk have showed Ea values between 9.7 and 55.3 kJ•mol-1, respectively. For tomato juice solutions, the Arrhenius equation slope was not constant. The different Ea obtained indicate that different mechanisms are taking place at the various tested operating conditions. This work also proposes a mathematical equation to estimate the PAA concentration for solutions free of organic matter.

Peracetic acid is a powerful sanitizer that has only recently been introduced in the Brazilian food industry. The main disadvantage of this sanitizer is its decomposition rate. The main purpose of this paper is to present results obtained in experiments carried out to study the decomposition kinetics of peracetic acid in aqueous solutions at 25, 35, 40 and 45 °C. The decompositon of peracetic acid is a first-order reaction. The decomposition rate constants are between 1.71x10-3 h -1 for 25 °C and 9.64x10-3 h-1 for 45 °C. The decomposition rate constant is affected by temperature according to the Arrhenius equation, and the activation energy for the decomposition of peracetic acid in aqueous solutions prepared from the commercial formulation used in this work is 66.20 kJ/mol.