Evaluating the efficacy of sodium acid sulfate to reduce Escherichia coli O157:H7 and its biofilms on food-contact surfaces

Escherichia coli O157:H7 biofilms pose challenges to the food industry by facilitating pathogen persistence. Sodium acid sulfate (SAS), a food-acid with antimicrobial properties, is poorly understood for its biofilm-disrupting capabilities. Efficacy of SAS (0.1, 1, and 3%), to disrupt E. coli O157:H7 biofilms in-vitro and on food-contact surfaces, was compared with water, chlorine (200 ppm) and peracetic-acid (PAA; 200 ppm). Biofilms were formed in 96-well-plates or on stainless-steel (SS) and high-density-polyethylene (HDPE) at 0, 10 and 480 min. In-vitro biofilm disruption was determined by measuring absorbance (A595) of crystal violet bound to the biofilm. Biofilm disruption on SS and HDPE was visualized using scanning electron microscopy (SEM) and pathogen populations enumerated. Overall, SAS-treatments significantly (P < 0.05) disrupted E. coli O157:H7 biofilms in-vitro, with 1% (A595 = 0.249) and 3% (A595 = 0.260) being the most effective, compared to the control (A595 = 1.392). On SS and HDPE, E. coli O157:H7 was reduced to undetectable levels by all the treatments except water (P < 0.05), over 8 h (480 min). The SEM images revealed disrupted biofilms and inactivated bacterial cells on SS and HDPE treated with SAS. However, the same was not observed with chlorine and PAA. Sodium acid sulfate indicated its potential use as a biofilm-removing sanitizer in the food industry.