Effect of Chemical Sanitizers Alone or Combined with An Enzymatic Product Against Pseudomonas fluorescens Biofilms on Food-Grade Materials.

In food industries microorganisms could resist to the sanitization processes routinely carried out, due to their peculiar ability to aggregate into biofilms, thus adhering to materials such as stainless steel (SS), poly-tetra-fluoro-ethylene (PTFE), hydroxyapatite, polystyrene, glass, or rubber. Since biofilms are a matter of concern for food producers, in this paper two sanitizers of common use in the food industry, respectively based on quaternary ammonium salts and alcohols, were tested alone or in combination with an enzymatic product against three different Pseudomonas fluorescens strains. Six-day-old biofilms grown on SS or PTFE were tested by applying different concentrations of each sanitizer at different treatment times, up to 10 min. When used in combination with the enzymatic product, sanitizers were applied after the disaggregating effect of the enzymatic product itself. The use of sanitizers without the enzymatic product allowed to achieve a total eradication of the biofilms only at high concentrations after long treatment times. The use of the enzymatic product combined with each sanitizer, at concentrations and treatment times that previously did not prove effective in eradicating Pseudomonas biofilms, allowed to register from 5 to 8 logarithmic reductions in the concentrations of the detached cells and, in some cases, their total inactivation. A better performance was obtained on SS compared to PTFE.