The removal of foodborne pathogen biofilms with the treatment of ultrasound and/or organic acid

Abstract

The purpose of this study is to investigate the effect of ultrasound and/or organic acids against Escherichia coli and Listeria monocytogenes biofilms on microplates. In the inactivation trials, pathogen biofilms formed on microplates were exposed to 2% organic acid (acetic, citric, malic and lactic acid) and/or ultrasound for 10, 30 and 60 minutes. Biofilm detachment effect of treatment with US and/or organic acid was tested by microplate method based on measuring of optical density. In this study, the removal of foodborne pathogen biofilms varied depending on the treatment method (single or combined), the treatment time and the type of organic acid (P<0.05). The combined treatment with organic acid and ultrasound created additional biofilm detachment. 60 min ultrasound treatment with organic acids caused the highest removal of E. coli (77%) and L. monocytogenes (70%) biofilms. Lactic acid and malic acid among organic acids were the most effective against both of pathogen biofilms on microplates. With the increasing treatment time, the greater biofilm detachment was observed on microplates. The combination treatment of organic acid and ultrasound ensured safe and more effective decontamination against pathogen biofilms on microplates according to single treatment. These findings indicate that ultrasound treatment combined with organic acids can successfully be applied as an environmentally friendly biofilm detachment technique in food industry.