Effect of phytic acid and free available chlorine on the inactivation of antibiotic-resistant and foodborne pathogenic Bacillus spores during combinational disinfection

Comparative disinfection treatment incorporating phytic acid (PA) and free available chlorine (FAC) as single or combined agents was used to investigate the principle-based inactivation of antibiotic-resistant and foodborne pathogenic Bacillus spores (including that of Bacillus subtilis and Bacillus cereus) in suspended aqueous solutions or artificially infected fresh produce in terms of kinetics and mechanisms. According to an experimentally derived second-order rate constant, the response of the k value to PA pre-treatment for Bacillus spp. spores with combined treatment was much higher than that with single treatment, by 1.0–3.2 at pH 5.1, 1.7–6.6 at pH 6.9, and 1.4–14.4 at pH 8.7. Significant spore removal (>3-log) was achieved upon pre-treatment with PA at concentrations of 50–200 mg/L within 121 CT of FAC exposure regardless of pH. Compared to the single treatment, synergistic cell membrane rupture in spores was observed during the combination treatment. The results are useful for optimizing combinational disinfection systems and promoting the inactivation of hazardous foodborne bacterial spores.