Microbe(s): Murine Norovirus surrogate for Human Norovirus
The ECOLOXTECH 240 system was used to generate a 50 ppm electrolyzed water solution of hypochlorous acid at pH 8 (25% solution of HOCl). Ceramic tile which had been innoculated with Murine Norovirus was treated with the hypochlorous acid solution for a contact time of 1 minute resulting in a 4-log reduction of Murine Norovirus.
Microbe(s): Escherichia coli ATCC 25922, Pichia pastoris GS115, Aureobasidium pullulans
The sanitising effect of low concentration neutralised electrolysed water (LCNEW, pH: 7.0, free available chlorine (FAC): 4 mg/L) combined with ultrasound (37 kHz, 80 W) on food contact surface was evaluated. Stainless steel coupon was chosen as attachment surface for Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012, representing bacteria, yeast and mold, respectively. The results showed that although LCNEW itself could effectively reduce survival population of E. coli ATCC 25922, P. pastoris GS115 and low concentration A. pullulans 2012 in planktonic status, LCNEW combined with ultrasound showed more sanitising efficacy for air-dried cells on coupons, with swift ificantly reduced the survival cells both on coupons and in suspension for all three strains. The results suggest that LCNEW combined with ultrasound is a promising approach to sanitise food equipment.
Microbe(s): Pseudomonas aeruginosa, Enterococcus faecalis, Micrococcus luteus
In the dairy industry, cleaning and disinfection of surfaces are important issues and development of innovative strategies may improve food safety. This study was aimed to optimize the combined effect of alkaline electrolyzed water (AEW) and neutral electrolyzed water (NEW) as s were significantly affected by surface roughness electropolished SSP required 10 min, 100 mg/L AEW at 30 C, whereas SSP without modification required 30 min, 300 mg/L AEW at 30 C. From confirmatory tests cells removed were 3.90 0.25 log CFU/cm2 for electropolished SSP, and 3.20 0.20 log CFU/cm2 for SSP without modification. NEW is non-corrosive, and can be advantageously used for environmentally friendly cleaning and disinfection processes.
Microbe(s): Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes
Electrochemically activated water (ECAW), also known as electrolyzed water, and ozonized water are typically effective in inactivating bacteria, but their generation typically uses high current and voltage. A few simpler antimicrobial technologies that are also based on the application of a mild electrical current have been recently marketed to food retail and service customers claiming to have sanitizing properties for controlling bacteria. The objective of this study was to determine the sanitizing effect of some of these commercial technologies on Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica and compare them with sterile water, generated ECAW generated with a pilot size electrolyzing unit, and salt solutions sprayed using commercial device sprays. A concentration of 100 mg/L ECAW had sanitizing effects of at least 5 log CFU/mL reductions on liquid culture and more than 4 log CFU/coupon reductions for E. coli O157:H7, L. monocytogenes and Salmonella dried on stainless steel surface, respectively. No bacterial cells were detected by direct plate counting post-ECAW treatment. In contrast, the treatment of liquid cultures with any of the commercial technologies tested resulted in non-significant bacterial cell reductions greater than 0.5 log CFU/mL. Similarly, when cells had been dried on metal surfaces and treated with any of the water generated with those technologies, no reductions were observed. When the manufacturer s instructions were followed, the reduction of cells on surface was largely due to the physical removal by cloth-wiping after water fraction application. These results indicate that treatment with any of these portable technologies had no noticeable antimicrobial activity. These results would be helpful for guiding consumers when choosing a right sanitization to ensure food safety.
Microbe(s): Escherichia coli, Staphylococcus epidermidis
This study investigated residual bacteria and different food types left on tableware items after various washing and sanitization protocols. Escherichia coli K-12 and Staphylococcus epidermidis were inoculated into whole milk and soft cream cheese. The milk was used to contaminate regular drinking glasses and the cheese was used to contaminate plates and silverware. These tableware items were washed in manual (43 C) and mechanical (49 C) washers and sanitized with different sanitizers (24 C) for 5 s. Quaternary ammonium compound, sodium hypochlorite, peroxyacetic acid, neutral electrolyzed water (NEW), and a combination of citric acid with sodium dodecylbenzene sulfonate (acidic formulation) were used as the chemical sanitizers. Tap water was used as a control. Results showed that at least 5-log reductions in both bacterial numbers were achieved for all sanitizers in both types of washers, except for the control. With mechanical dishwashing, the NEW and acidic formulation treatments reduced bacterial populations by >6.9 and >6.0 log CFU per tableware item, respectively. With the manual operation, bacterial numbers were reduced by >5.4 and >6.0 log CFU per tableware item, respectively. This study revealed that NEW and the acidic formulation are as effective as the other chemical sanitizers for food contact surface sanitization in manual and mechanical ware washing.
Microbe(s): Listeria monocytogenes
All food processing surfaces are potential sites for biofilm formation of foodborne pathogens, which may result in increased virulence and better adaptation to survival in foods. This study was aimed to evaluate the effect of two antimicrobials, neutral electrolyzed water (NEW) and nisin, and their combination, on Listeria monocytogenes Scott A biofilms formed on glass and stainless steel surfaces. We also examined the effects of sub-lethal doses of NEW on listeriolysin O (LLO) activity from free and biofilm listerial cells. Coupons inoculated with L. monocytogenes cells were used to produce biofilms by incubation for four days at 37 C. An orthogonal experimental design with two replicates was used to test the effect of four factors on biofilm population. The factors were antimicrobial agents: NEW (65 ppm), nisin (6976 IU/per coupon), and their combination; temperature: 20 C and 37 C; contact time: 5, 10, 20 and 45 min; and type of material: glass or stainless steel. Antimicrobial compounds and exposure time significantly affected L. monocytogenes populations in biofilms from both surfaces. A bactericidal effect was shown by NEW on free listerial cells at 30 ppm for 0.5 min of exposure, regardless treatment temperature. Same effect was observed on listerial biofilms at 65 ppm or higher concentrations, after 10 min contact time. A sub-lethal concentration of NEW acting on listerial biofilms resulted in an increased LLO activity, while non-treated biofilms exhibited a reduced activity, but higher than that found for free cells. The use of NEW as a sanitizer may be effective in reducing bacterial contamination. In addition because of its safety, which would benefit the food industry and its environmental friendliness, NEW may be of significant use in the food industry.
Microbe(s): Escherichia coli, Listeria innocua
The effectiveness of neutral electrolyzed water (NEW) to sanitize cutting boards used for food preparation was investigated. Cutting boards made of hardwood and bamboo were inoculated with Escherichia coli K12 and Listeria innocua, dried for 1 h, washed, rinsed and sanitized with NEW, sodium hypochlorite (NaClO) solution, or tap water (control). After each washing protocol, surviving bacterial populations were determined. Results showed that both NEW and NaClO sanitizing solutions produced similar levels of bacterial reductions. In manual washing, the population reductions by NEW and NaClO were 3.4 and 3.6 log10 CFU/100 cm2 for E. coli, and 4.1 and 3.9 log10 CFU/100 cm2 for L. innocua, respectively. In the automatic washing, the reductions by NEW and NaClO were 4.0 and 4.0 log10 CFU/100 cm2 for E. coli, and 4.2 and 3.6 log10 CFU/100 cm2 for L. innocua, respectively. No significant differences (P > 0.05) were observed in surviving bacteria counts when comparing board material types.
Microbe(s): Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus
This study evaluated the efficacy of neutral electrolyzed water (NEW; 64.1 mg/liter of active chlorine) to reduce populations of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Listeria monocytogenes on plastic and wooden kitchen cutting boards. Its effectiveness was compared with that of a sodium hypochlorite solution (NaClO; 62.3 mg/liter of active chlorine). Inoculated portions of cutting boards were rinsed in either NEW or NaClO solutions, or deionized water (control). Plastic boards were rinsed for 1 min and wooden boards for 1 and 5 min. After each treatment, the surviving population of each strain was determined on the surface and in the soaking water. No significant difference (P 0.05) was found between the final populations of each strain with regard to the treatment solutions (NEW or NaClO). However, a significant difference (P 0.05) was revealed between surface materials after 1 min of washing. Whereas in plastic boards the initial bacterial populations were reduced by 5 log CFU/50 cm2, in wooden cutting boards they underwent a reduction of <3 log CFU/50 cm2. A 5-min exposure time yielded reductions of about 4 log CFU/50 cm2. The surviving populations of all bacteria in NEW and NaClO washing solutions were <1 log CFU/ml after soaking both surfaces. This study revealed that NEW treatment is an effective method for reducing microbial contamination on plastic and wooden cutting boards. NEW efficacy was comparable to that of NaClO, with the advantage of having a larger storage time.
Microbe(s): Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus
Aim: To ascertain the efficacy of neutral electrolysed water (NEW) in reducing Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes on glass and stainless steel surfaces. Its effectiveness for that purpose is compared with that of a sodium hypochlorite (NaClO) solution with similar pH, oxidation-reduction potential (ORP) and active chlorine content. Methods and Results: First, the bactericidal activity of NEW was evaluated over pure cultures (8-5 log CFU ml-1) of the abovementioned strains: all of them were reduced by more than 7 log CFU ml-1 within 5 min of exposure either to NEW (63 mg l-1 active chlorine) or to NaClO solution (62 mg l-1 active chlorine). Then, stainless steel and glass surfaces were inoculated with the same strains and rinsed for 1 min in either NEW, NaClO solution or deionized water (control). In the first two cases, the populations of all the strains decreased by more than 6 log CFU 50 cm-2. No significant difference (P 0 05) was found between the final populations of each strain with regard to the treatment solutions (NEW or NaClO solution) or to the type of surface. Conclusions: NEW was revealed to be as effective as NaClO at significantly reducing the presence of pathogenic and spoilage bacteria (in this study, E. coli, L. monocytogenes, P. aeruginosa and S. aureus) on stainless steel and glass surfaces. Significance and Impact of the Study: NEW has the advantage of being safer than NaClO and easier to handle. Hence, it represents an advantageous alternative for the disinfection of surfaces in the food industry.
Microbe(s): Vibrio parahaemolyticus
AIM: To determine the efficacy of electrolysed oxidizing (EO) water in inactivating Vibrio parahaemolyticus on kitchen cutting boards and food contact surfaces. METHODS AND RESULTS: Cutting boards (bamboo, wood and plastic) and food contact surfaces (stainless steel and glazed ceramic tile) were inoculated with V. parahaemolyticus. Viable cells of V. parahaemolyticus were detected on all cutting boards and food contact surfaces after 10 and 30 min, respectively, at room temperatures. Soaking inoculated food contact surfaces and cutting boards in distilled water for 1 and 3 min, respectively, resulted in various reductions of V. parahaemolyticus, but failed to remove the organism completely from surfaces. However, the treatment of EO water [pH 2.7, chlorine 40 ppm, oxidation-reduction potential 1151 mV] for 30, 45, and 60 s, completely inactivated V. parahaemolyticus on stainless steel, ceramic tile, and plastic cutting boards, respectively. CONCLUSIONS: EO water could be used as a disinfecting agent for inactivating V. parahaemolyticus on plastic and wood cutting boards and food contact surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: Rinsing the food contact surfaces with EO water or soaking cutting boards in EO water for up to 5 min could be a simple strategy to reduce cross-contamination of V. parahaemolyticus during food preparation.
Microbe(s): Escherichia coli O157:H7, Listeria monocytogenes
One milliliter of culture containing a five-strain mixture of Escherichia coli O157:H7 (1010 CFU) was inoculated on a 100-cm2 area marked on unscarred cutting boards. Following inoculation, the boards were air-dried under a laminar flow hood for 1 h, immersed in 2 liters of electrolyzed oxidizing water or sterile deionized water at 23 C or 35 C for 10 or 20 min; 45 C for 5 or 10 min; or 55 C for 5 min. After each temperature-time combination, the surviving population of the pathogen on cutting boards and in soaking water was determined. Soaking of inoculated cutting boards in electrolyzed oxidizing water reduced E. coli O157:H7 populations by 5.0 log CFU/100 cm2 on cutting boards. However, immersion of cutting boards in deionized water decreased the pathogen count only by 1.0 to 1.5 log CFU/100 cm2. Treatment of cutting boards inoculated with Listeria monocytogenes in electrolyzed oxidizing water at selected temperature-time combinations (23 C for 20 min, 35 C for 10 min, and 45 C for 10 min) substantially reduced the populations of L. monocytogenes in comparison to the counts recovered from the boards immersed in deionized water. E. coli O157:H7 and L. monocytogenes were not detected in electrolyzed oxidizing water after soaking treatment, whereas the pathogens survived in the deionized water used for soaking the cutting boards. This study revealed that immersion of kitchen cutting boards in electrolyzed oxidizing water could be used as an effective method for inactivating foodborne pathogens on smooth, plastic cutting boards.
Microbe(s): Enterobacter aerogenes, Staphylococcus aureus
The effectiveness of electrolyzed (EO) water at killing Enterobacter aerogenes and Staphylococcus aureus in pure culture was evaluated. One milliliter (approximately 109 CFU/ml) of each bacterium was subjected to 9 ml of EO water or control water (EO water containing 10% neutralizing buffer) at room temperature for 30 s. Inactivation (reduction of >9 log10 CFU/ml) of both pathogens occurred within 30 s after exposure to EO water containing approximately 25 or 50 mg of residual chlorine per liter. The effectiveness of EO water in reducing E. aerogenes and S. aureus on different surfaces (glass, stainless steel, glazed ceramic tile, unglazed ceramic tile, and vitreous china) was also evaluated. After immersion of the tested surfaces in EO water for 5 min without agitation, populations of E. aerogenes and S. aureus were reduced by 2.2 to 2.4 log10 CFU/cm2 and by 1.7 to 1.9 log10 CFU/cm2, respectively, whereas washing with control water resulted in a reduction of only 0.1 to 0.3 log10 CFU/cm2. The washing of tested surfaces in EO water with agitation (50 rpm) reduced populations of viable cells on the tested surfaces to <1 CFU/cm2. For the control water treatment with agitation, the surviving numbers of both strains on the tested surfaces were approximately 3 log10 CFU/cm2. No viable cells of either strain were observed in the EO water after treatment, regardless of agitation. However, large populations of both pathogens were recovered from control wash solution after treatment.
Microbe(s): Murine Norovirus surrogate for Human Norovirus
The ECOLOXTECH 240 system was used to generate a 50 ppm electrolyzed water solution of hypochlorous acid at pH 5 (99% solution of HOCl). Ceramic tile which had been innoculated with Murine Norovirus was treated with the hypochlorous acid solution for a contact time of 1 minute resulting in a 5-log reduction of Murine Norovirus.