Effectiveness of cleaning techniques used in the food industry in terms ofthe removal of bacterial biofilms

The effectiveness of cleaning was investigated through food factory trials and laboratory experiments using a naturally occurring biofilm from a food factory environment and generated biofilms. The efficacy of factory cleanin g and disinfection programmes was assessed by swabbing and total viable cou nt (TVC) analysis of surfaces before cleaning, after cleaning and after dis infection. Cleaning produced a 0.91 log reduction in the attached populatio n. Investigation of the effectiveness of a variety of cleaning methods in t he removal of a naturally occurring food factory biofilm showed that the hi gh pressure spray and the mechanical floor scrubber,which use a high degree of mechanical action, were most effective. Cleaning trials with biofilms o f Pseudomonas aeruginosa or Staphylococcus aureus showed that spraying with water at pressures of 34.5, 51.7 and 68.9 bar did not significantly increa se the removal, as assessed by direct epifluorescent microscopy (DEM) and s wabbing and TVC analysis, beyond the three log reduction observed at 17.2 b ar. The effect of spray time at 17.2 bar showed that increasing spray time from 1 to 10 s did not significantly increase removal of Ps. aeruginosa bio film. Investigation of the optimum distance of the spray lance from the sur face at 17.2 bar was found to be between 125 and 250 mm. The use of an alka line, acidic or neutral detergent prior to spraying with water at 17.2 bar did not significantly increase the removal of Ps. aeruginosa or Staph. aure us. However, the acidic and alkaline products significantly (P = 0.05) affe cted the viability of Staph. aureus and Ps. aeruginosa, respectively, there by minimizing the potential for the spread of contamination.