Abstract: Bacillus cereus spores have the ability to adhere to solid surfaces, including stainless steel, a material widely used in food industries. Adhesion of spores allows recontamination during food processing, and cleaning and disinfection are largely used by industries to control them. Hence, this study aims to assess the detachment capacity (or removing activity) of detergents based on sodium hydroxide, nitric acid, phosphoric acid, and chlorine against two adhered B. cereus spores (one hydrophobic and other hydrophilic) to stainless steel surfaces. Microorganism adhesion on the surfaces reached 5.5 log CFU/cm2 for the two strains studied. Two protocols composed of combinations of chemical compounds, concentration, temperature, and contact time were tested. The inactivation kinetics shapes were convex and modeled by the Weibull model. The effects of temperature and biocide concentration were quantified using a Bigelow-like model. The temperature applied during the cleaning-in-place treatment is an important factor acting on the speed of inactivation or detachment of B. cereus spores. However, this efficiency depends on the hydrophobic characteristics of B. cereus spores. The concentration of detergent and acid also affects the inactivation rate, whereas the characteristic of hydrophobicity does not intervene for the chlorine alkaline treatments.
Keywords: Bacillus cereus; Adhered spores; Cleaning; Hydrophobicity; Stainless steel surface.
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