Microbial evaluation of the biotransfer potential from surfaces with Bacillus biofilms after rinsing and cleaning procedures in closed food-processing systems

The biotransfer potential in food processing is defined as the ability of the microorganisms present on equipment surfaces both before and after cleaning procedures to contaminate products during processing. Growth of Bacillus biofilms was detectable on both stainless-steel and Teflon© surfaces after all the cleaning procedures. B. cereus and B. subtilis cells adhered more firmly to unsoiled than to soiled surfaces, whereas B. thuringiensis adhered most firmly to soiled surfaces. The results showed that the removal of biofilms from surfaces was more difficult from stainless steel because the microorganisms were attached more tenaciously to rough surfaces. Biofilms were cleaned most effectively from unsoiled surfaces with a simple rinsing procedure; thus the mechanical forces of the flow are very important in the cleaning. The chemical and heat treatments used for cleaning had the greatest impact on the abundance of living microorganisms. All the procedures tested did not remove biofilm material effectively from the surfaces. Significantly more cells were removed when the alkaline phase in the alkaline-acid treatment of the cleaning-inplace (CIP) procedure was prolonged, and ethylene diaminetetraacetic acid (EDTA) was used.