Abstract Aims Biofilm is a continuing issue of food microbial safety. This study combined microbubble (MB) with 50 mg/L sodium hypochlorite (NaClO) or chlorine dioxide (ClO2) to inactivate the biofilms of Salmonella Typhimurium and Staphylococcus aureus on stainless steel (SS) and polyvinyl chloride (PVC). Methods and Results The biofilms were treated with the combinations of MB and NaClO (NMB) or ClO2 (CMB). After 10-min treatment, populations of S. Typhimurium on SS were below the detection limit (1.1 log CFU piece−1) for NMB and 2.6 log CFU piece−1 for CMB; the populations on PVC were 1.6 and 3.3 log CFU piece−1 for NMB and CMB, respectively. For S. aureus, 7.5-min NMB and CMB treatments reduced the populations on SS to below the detection limit and 1.6 log CFU piece−1, respectively; and to 1.3 log CFU piece−1 on PVC. Compared with water washing and sanitizers alone, NMB and CMB obtained an additional 5 to 6 log reductions. Higher residual populations of both bacteria were obtained on PVC, and S. Typhimurium had higher residual populations on both surfaces. Observation under a scanning electron microscope revealed that no biofilm remained on the NMB-treated SS and PVC pieces, but biofilm remained on the NaClO and water-treated pieces. Furthermore, calcofluor white staining confirmed that NMB treatment achieved the greatest removal of extracellular substances. Conclusion This is the first study showing that the combinations of MB and sanitizers inactivate the biofilm of these two bacteria on SS and PVC and demonstrate the potential for application in the food industry.
Hou et al. (Wed,) studied this question.