REMOVAL OF MICROORGANISMS FROM POLYMER BOTTLES BY CAUSTIC WASHING

Six different materials (glass, high density polyethylene (HDPE), poly ethylene terephtalate (PET), polypropylene (PP), polycarbonate (PC) an d polyvinylchloride (PVC)) used for bottle production were tested for their microbial rinsability. A comparative study was made between the roll-culture method and the rinsing method to determine the remaining microorganisms on caustic cleaned PET bottle inner surfaces Only one-t hird of the microorganisms detected with the roll-culture method were detected with the generally applied rinsing method. Staphylococcus aur eus and Bacillus cereus were compared in their potential to attach to the different bottle materials and Bacillus cereus showed less persist ency against caustic cleaning compared to Staphylococcus aureus The in fluence of the caustic cleaning parameters on the remaining microorgan isms was examined. Temperature had a limited influence on the removal of microorganisms from surfaces. The effect of the commercial additive and the caustic concentration used was clearly more pronounced but de pended strongly on the type of material. Optimization of the caustic c leaning process led to much better cleaning effectiveness. When optima l conditions were applied the following classification in decreasing o rder of microbial rinsability of the examined materials could be made: glass > PET > PC > PP = PVC > HDPE.