Efficacy of electrolyzed water as a sanitizer and cleaning agent and its effect on food contact surfaces
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Biofilms are potential sources of contamination to food in processing plants, because they frequently survive sanitizer treatments during cleaning. This research investigated the sequential use of alkaline and acidic electrolyzed oxidizing (EO) water in the inactivation of Listeria monocytogenes biofilms on stainless steel surfaces in the presence or absence of organic matter. Alkaline EO water did not exert any bactericidal action on the L. monocytogenes biofilms, however, acidic EO water produced a reduction of 4-5 log CFU/ coupon and the sequential treatment resulted in additional inactivation. Results suggested that alkaline and acidic EO water can be utilized together to achieve a better inactivation of biofilms than when applied individually. The addition of organic matter in the form of chicken serum, to acidic EO water, decreased its oxidizing capacity and chlorine concentration. Organic matter reduced the bactericidal activity of acidic EO water on both plantonic cells and biofims of L. monocytogenes and the extent of reduction was dependent on the organic load. The effect of EO water on various materials which can be found in food processing environments was also investigated. ASTM A-36 medium carbon steel, 110 copper, 3003-H14 aluminum, polyvinylchloride (PVC) type 1, and 304 stainless steel were subjected to standardized corrosion tests in acidic EO water, chlorine water, modified EO water and deionized water. Carbon steel which had a fair corrosion resistance to acidic EO water, was the most affected material. Stainless steel, which is the most commonly used material for food processing equipment fabrication, had an outstanding corrosion resistance to acidic EO water. A laboratory scale conveyor system was evaluated for the application of acidic EO water in the inactivation of L. monocytogenes biofilms on teflon and stainless steel surfaces. Biofilms on teflon were much more resistant than biofilms on stainless steel. Acidic EO water maintained a large part of its bactericidal efficacy even after being reused several times. This research demonstrates that acidic EO water can be reused several times during immersion cleaning without significant reduction in its bactericidal efficacy or the probability of recontamination from the used water.