Impact of temperature application and concentration of commercial sanitizers on inactivation of food-plant fungal spores

This study aimed at quantifying the impact of the concentration of four commercial sanitizers and temperature on mold spores inactivation. The sanitizers were based on the following fungicide molecules, ethanol (ARVO 21 SR), active chlorine (ARVO CLM 600), hydrogen peroxide (Nocolyse Food) and triamine (P3 Topax 960). Food plant spores were produced under a moderate water stress, 0.95 aw and dry-harvested to simulate airborne spores responsible for contamination in the food industry. First, Aspergillus flavus, Cladosporium cladosporioides, Mucor circinelloides, and two Penicillium commune isolates were tested against the sanitizers at 20 °C and at a concentration recommended by the manufacturers. Overall, A. flavus was the less resistant species. Second the effects of concentration and temperature were assessed on the most resistant species, i.e., P. commune UBOCC-A-116003 (ARVO 21 SR and P3 Topax 960), P. commune UBOCC-A-112059 (ARVO CLM 600), and M. circinelloides (Nocolyse Food). With the exception of ARVO 21 SR, the observed inactivation kinetics were downward concave. The time necessary to obtain 4 log reduction, t₄D, was estimated by means of the Weibull model. At 20 °C and at the recommended concentration by the manufacturers, t₄D (min) for the most resistant strains were equal to 2.14 (ARVO 21 SR), 7.35 (ARVO CLM 600), 39.3 (Nocolyse Food) and 82.8 (P3 Topax 960). T₄D was increased at lower concentrations and temperatures. These effects were more pronounced for ARVO 21 SR, t₄D were about 10 fold and 20 fold the above reported value, 2.14 min, at 8 °C and by diluting the sanitizer by a 10:8 factor, respectively. The least effect of temperature, 3 fold, was shown for ARVO CLM 600, while concentration of P3 Topax 960 had no significant effect on t₄D within the recommended utilization range.