Bactericidal activity of neutral electrolyzed water (NEW) was investigated against endospore forming Bacillus cereus and Clostridium perfringens in cell suspensions and artificially inoculated onto the surface of selected fresh produce items (cherry tomato, miniature cucumber, carrot and parsley) and polypropylene cutting boards at ambient temperature (22 °C). Viable counts of survivors were determined within 0 (untreated control), 1, 3 and 5 min of treatment at ambient temperature using NEW solutions of 60 and 120 mg/L free available chlorine FAC. All treatments showed significant differences (P < 0.05) in bacterial reductions with regard to contact time and concentration used and which maximized after 5 min of treatment at 120 mg/L FAC. For cell suspensions, the extent of reduction (log10 CFU/mL) after 5 min of treatment ranged from 2.11 to 3.03 for B. cereus and 2.46–3.62 for C. perfringens at 60 and 120 mg/L FAC, respectively. However, when the bacteria inoculated onto the produce items and cutting boards showed greater resistance to NEW treatments compared to cell suspensions. Sterile deionized water did not contribute any significant reduction (P > 0.05) after 5 min of treatment, whereas bacterial viability of the inoculated produce was reduced by 2.11–2.30 and 2.41–3.16 log10 CFU/g when NEW used at 120 mg/L FAC for B. cereus and C. perfringens, respectively. When inoculated cutting boards were sprayed with NEW at 120 mg/L FAC and after 5 min of treatment, cell viability was reduced by 2.33 and 3.06 log10 per 100 cm2 for B. cereus and C. perfringens, respectively. This study showed that NEW could be used as an effective bactericidal treatment alternative to commonly used chemical sanitizers against endospore forming bacteria.
Bibliographical noteFunding Information:
This research was supported by the School of Food Science at the University of Idaho and Washington State University ; The College of Agricultural and Life Science, University of Idaho ; The Agriculture Experiment Stations at the University of Idaho and Washington State University and the School of Agriculture at the University of Jordan .
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- Endospore forming bacteria
- Fresh produce
- Neutral electrolyzed water