Effectiveness of sodium hypochlorite and benzalkonium chloride in reducing spoilage yeast biofilms on food contact surfaces

The study evaluates the effectiveness of sodium hypochlorite (NaOCl) and a commercial quaternary ammonium compound (QAC) against planktonic and biofilm-associated yeast (Candida tropicalis, C. krusei, C. kefyr, and Rhodotorula mucilaginosa) isolated from ultrafiltration modules in a clarified apple juice production facility. The results demonstrated that the efficacy of disinfection against planktonic yeast cells did not directly correlate with the effectiveness against biofilm embedded cells. QAC proved to be more effective than NaOCl in reducing yeast biofilms, achieving a higher than 3-log10 reduction in cell counts. In contrast, NaOCl, even at its maximum permissible concentration for food-contact surfaces, exhibited limited efficacy against biofilms. Both disinfectants had limited success in preventing biofilm regrowth, indicating the potential for persistent contamination in food processing environments. Furthermore, both agents compromised biofilm structure, with QAC having a significantly more pronounced impact than NaOCl.