Modeling of sporicidal effect of hydrogen peroxide in the sterilization of low density polyethylene film inoculated with Bacillus subtilis spores

Abstract

The sporicidal effect of hydrogen peroxide (H(2)O(2)) in the sterilization of low density polyethylene film (LOPE) was evaluated using a Central Composite Design (CCD). The effects of contact time (5-19s), bath temperature (23-70 degrees C) and concentration of H(2)O(2) (0-35%) in an immersion bath were investigated. A 16 cm(2) film surface was evenly inoculated with 100 mu L of the test microorganism Bacillus subtilis var. globigii ATCC9372 spores. The effective H(2)O(2) sporicidal activity was demonstrated at concentrations from 18 to 35% and in a temperature range from 46 to 70 degrees C, resulting in 2-7 decimal reductions of B. subtilis spores. A quadratic mathematical model representative of the action of H(2)O(2) on the B. subtilis spores was developed as a function of concentration, time and temperature. Test specimens sanitized with 28% H(2)O(2) at 60 degrees C for 8 s showed 4 decimal reductions. In the same sterilization procedure, but extending the time to 16 s, this value increased to 7 decimal reductions, demonstrating the efficiency of H(2)O(2) as a function of contact time. The sterilization system tested showed satisfactory performance in the sterilization of LDPE films, being capable of reaching up to 7 decimal reductions of the bacterial spore population. (C) 2011 Elsevier Ltd. All rights reserved.