Influence of the surface temperature of packaging specimens on the inactivation of Bacillus spores by means of gaseous H2O2

Abstract

To determine the influence of condensation as a function of the surface temperature of aseptic packaging, on the inactivation of Bacillus spores [Bacillus subtilis (DSM 347), B. subtilis SA22, Bacillus atrophaeus] having different surface properties by means of vaporized H(2) O(2). The packaging specimens inoculated with Bacillus spores were tempered and subsequently exposed to H(2) O(2) -vapour. During the exposure, surface temperature curves were measured and the spore survival was determined. Results showed that decreasing the initial surface temperature of the packaging specimens had a positive effect on the sporicidal activity of H(2) O(2) -vapour, where the effect was less pronounced for less hydrophilic spores. The surfaces of spores were characterized by means of the water contact angle. For starting surface temperatures below the dew point temperature of the sterilant gas, the condensation of highly concentrated liquid H(2) O(2) on the packaging surface accelerates the killing of the spores, while the inferior wettability of more hydrophobic spores compared to more hydrophilic ones diminishes the effect. Regarding industrial packaging sterilization, a mixed microflora has to be inactivated. Promoting the condensation of H(2) O(2) improves in general the killing of different species of spores, however, at various degrees depending on the wettability of spores.