Abstract:

In this study, the antimicrobial activity of neutral electrolyzed water (NEW) on Bacillus cereus forming endospore, Escherichia coli and, toxin producer Aspergillus flavus and Penicillium expansum was determined both on the surface of steel plates in the presence of organic matter artificially inoculated and in cell suspensions. Also, the antimicrobial efficiency of NEW was compared to that of Sodium hypochlorite (NaClO). Experiments were carried out at room temperature (22 °C). 1% sodium hypochlorite solution (with 531 ppm free chlorine), and different concentrations of NEW, 5% (with 63 ppm free chlorine), 10% (with 120 ppm free chlorine), and 15% (with 187 ppm free chlorine) were used for the comparison. Cell suspensions and stainless-steel plates inoculated with a final 10% liquid fig solution were treated with NEW and NaClO for 0 (untreated, control), 15, 30, and 60 seconds. Then, viable cell counts both in cell suspensions and on the inoculated stainless-steel plates were determined. It was determined that there were significant differences (P<0.05) in the decrease in the number of microorganisms depending on the application time and free chlorine concentration. The reduction ratios (%) in cell suspensions after 60 seconds of treatment with NEW ranged from 48.8 to 100 for E. coli, 11.39 – 32.23 for B. cereus and, 31.12 – 100 for A. flavus. The reduction ratio for P. expansum was %100 for all concentrations of NEW after 60 sec. After 60 seconds application of 1% NaClO to the cell suspensions, the reduction ratios (%) were determined to be 29.56, 23.48, 39.19 and 69.92 for E. coli, B. cereus, A. flavus and P. expansum, respectively. However, in the experiments performed after inoculation of microorganisms and sterile 10% liquid fig solution on the surface of steel plates, it was observed that microorganisms showed greater resistance to NEW and 1% NaClO compared to direct application to the cell suspension. The reduction ratios (%) on the surface of steel plates after 60 seconds of treatment with NEW ranged from 17.66 to 40.07 for E. coli, 23.93–31.77 for B. cereus, 10,91–30,91 for A. flavus and, 49.77–64.85 for P. expansum. After 60 seconds application of 1% NaClO on the surface of steel plates, the reduction ratios (%) were 19.38, 11.70, 7.5 and 46.52 for E. coli, B. cereus, A. flavus and P. expansum, respectively. The results of this study showed that 15% NEW can be used as a strong bactericide and fungicide against endospore-forming bacteria and toxin-producing fungi. Also, 15% NEW is more effective than 1% NaClO in cleaning the surfaces used for fig processing. Therefore, NEW also can be a good alternative to commonly used disinfectants. This is the first report on the use of NEW as a fungicide and bactericide on fig processing surfaces in the fig industry.

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