Purpose: In canning industry, there is a strong need of alternative technologies able to decontaminate heat resistant spores in dry products. We investigated a gaseous biocide technology with industrial isolates inoculated as spores.
Methods: An automated dispersion system is used to vaporize H2O2 liquid solution in dry air stream, in order to obtain a uniform distribution of the sporicidal agent (Vaporized Hydrogen Peroxide or VHP), in the enclosure. This chemical decontamination process is achieved at moderate temperature (< 60°C) with a low relative humidity (less than 5%). First, the efficiency was tested with biotest and secondly, inoculated foods were used. Species were selected for their specific interest in the canned food industry (Moorella, Thermoanaerobacterium, Geobacillus stearothermophilus and Bacillus coagulans).
Results: In a first step the ability of the VHP process to destroy highly resistant spores deposited in dry state on biological indicators (stainless steel samples) and then exposed to different VHP treatments was determined. More than 5 logs of spores were decontaminated for G. stearothermophilus while only 3 logs of destruction were observed with Moorella, known to be the most heat resistant spore species. In a second step, 5 different kinds of dry food products – spices or dehydrated vegetables – artificially contaminated with the same species spores were exposed to VHP. Nature of the dry food (i.e. garlic powder) impacted the decontamination efficiency.
Significance: This study shows that the VHP treatment is effective for the reduction of heat resistant spores even at low temperature and may be suitable for the treatment of dry and dehydrated products with limited impact on the food characteristics.