Electrolyzed water (EW) is gaining popularity as a sanitizer in the food industries of many countries. By electrolysis, a dilute sodium chloride solution dissociates into acidic electrolyzed water (AEW), which has a pH of 2 to 3, an oxidationreduction potential of >1,100 mV, and an active chlorine content of 10 to 90 ppm, and basic electrolyzed water (BEW), which has a pH of 10 to 13 and an oxidation-reduction potential of -800 to -900 mV. Vegetative cells of various bacteria in suspension were generally reduced by >6.0 log CFU/ml when AEW was used. However, AEW is a less effective bactericide on utensils, surfaces, and food products because of factors such as surface type and the presence of organic matter. Reductions of bacteria on surfaces and utensils or vegetables and fruits mainly ranged from about 2.0 to 6.0 or 1.0 to 3.5 orders of magnitude, respectively. Higher reductions were obtained for tomatoes. For chicken carcasses, pork, and fish, reductions ranged from about 0.8 to 3.0, 1.0 to 1.8, and 0.4 to 2.8 orders of magnitude, respectively. Considerable reductions were achieved with AEW on eggs. On some food commodities, treatment with BEW followed by AEW produced higher reductions than did treatment with AEW only. EW technology deserves consideration when discussing industrial sanitization of equipment and decontamination of food products. Nevertheless, decontamination treatments for food products always should be considered part of an integral food safety system. Such treatments cannot replace strict adherence to good manufacturing and hygiene practices.

Shewanella putrefaciens is an important specific spoilage organism (SSO) in seafood under low-temperature storage and can form biofilms on seafood processing-related contact surfaces, which exacerbates seafood spoilage and causes food safety problems. The characterization of and dynamic change in biofilms formed by Shewanella putrefaciens on three seafood processing-related contact surfaces were investigated in this study. An effective strategy to eliminate mature biofilms by acidic electrolysis water (AEW) was provided. Shewanella putrefaciens can form biofilms on glass, stainless steel and polystyrene, which are closely connected with surface properties such as hydrophilicity/hydrophobicity and surface roughness. AEW can be an excellent choice to clean mature biofilms formed by S. putrefaciens. AEW at a concentration of 3 g/L can remove almost all biofilms on the three common food contact materials tested. There is a bactericidal effect on the biofilm, reducing the possibility of secondary contamination. This study will contribute to promoting the application of AEW for controlling biofilms during seafood processing.

The efficacy of electrolyzed water (EW) to inactivate Listeria monocytogenes on stainless steel surfaces was evaluated and modelled in the present study. L. monocytogenes was inoculated on stainless steel coupons and subsequently subjected to Neutral EW (NEW, pH = 7.0) and Slightly Acid EW (SAEW, pH = 5.0) with different Available Chlorine Concentration (ACC, 50–200 mg/L) for different exposure times (0–6 min). The number of viable cells on coupons decreased as the exposure time increased at all ACC concentrations. Treatments with SAEW resulted in higher reductions of L. monocytogenes, i.e., 2.30 ± 0.16 to 5.64 ± 0.11 log cfu/cm², in comparison with NEW treatments (1.55 ± 0.11 to 5.22 ± 0.12 log cfu/cm²), probably due to the synergistic bactericidal effect between the acidic pH, higher oxidation-reduction potential and the effective form of chlorine, reported in previous studies. Since SAEW was the most effective against L. monocytogenes, two approaches were tested to model the survival data: the one- and two-step modelling procedures. The Weibull model was suitable to describe the survival data and both approaches produced suitable survival models (adj-R²>0.92 and MSE<0.2). EW is effective in reducing bacterial contamination on food-contact surfaces and the survival data and models derived from this study are relevant to optimize its use as an environment-friendly sanitizer in the food industry.

Engineered water nanostructures (EWNS) synthesized utilizing electrospray and ionization of water, have been, recently, shown to be an effective, green, antimicrobial platform for surface and air disinfection, where reactive oxygen species (ROS), generated and encapsulated within the particles during synthesis, were found to be the main inactivation mechanism. Herein, the antimicrobial potency of the EWNS was further enhanced by integrating electrolysis, electrospray and ionization of de-ionized water in the EWNS synthesis process. Detailed physicochemical characterization of these enhanced EWNS (eEWNS) was performed using state-of-the-art analytical methods and has shown that, while both size and charge remain similar to the EWNS (mean diameter of 13 nm and charge of 13 electrons), they possess a three times higher ROS content. The increase of the ROS content as a result of the addition of the electrolysis step before electrospray and ionization led to an increased antimicrobial ability as verified by E. coli inactivation studies using stainless steel coupons. It was shown that a 45-min exposure to eEWNS resulted in a 4-log reduction as opposed to a 1.9-log reduction when exposed to EWNS. In addition, the eEWNS were assessed for their potency to inactivate natural microbiota (total viable and yeast and mold counts), as well as, inoculated E. coli on the surface of fresh organic blackberries. The results showed a 97% (1.5-log) inactivation of the total viable count, a 99% (2-log) reduction in the yeast and mold count and a 2.5-log reduction of the inoculated E. coli after 45 min of exposure, without any visual changes to the fruit. This enhanced antimicrobial activity further underpins the EWNS platform as an effective, dry and chemical free approach suitable for a variety of food safety applications and could be ideal for delicate fresh produce that cannot withstand the classical, wet disinfection treatments.

To determine the efficacy of electrolysed oxidizing (EO) water in inactivating Vibrio parahaemolyticus on kitchen cutting boards and food contact surfaces. 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. EO water could be used as a disinfecting agent for inactivating V. parahaemolyticus on plastic and wood cutting boards and food contact surfaces. 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.

The Weibull distribution function can be used to describe cleaning kinetics of high pressure water jets. This function has been proposed previously to describe the soil removal of heat exchangers in milk industry during CIP processes. Weibull distribution function can be applied to model different types of kinetics by use of two parameters. Thus, characteristic cleaning times can be calculated more precisely than using an exponential function. This is necessary for proper simulation of the cleaning process of machines and equipment in food industry. Experimental trials were performed in cleaning milk protein soil from stainless steel plates with pressures from 20 to 60 bar at temperatures of 30–50 °C. In many cases, experimental data could be described equally well using an exponential function, but in specific cases, e.g. at low pressure (20 bar) or low temperature (30 °C), the Weibull distribution function resulted in much better fit.

These studies examined the effects of incorporating bubbles of air in the water used for cleaning surfaces. Small (<50 μm) or large (millimetre) bubbles were used, and these could aid cleaning by a scrubbing action, energy release or free radical production. Small or large bubbles improved the removal of biofilm from steel surfaces by 1.0 log₁₀ or 1.6 log₁₀, respectively. Biofilm removal from a polypropylene pipe wall was improved by 0.9 log₁₀ by incorporating bubbles into the cleaning water. Further trials showed increased removal of carbohydrate, fat and protein deposits from stainless steel by incorporating bubbles into the water. These results suggest that the use of air bubbles in water could provide small improvements in cleaning or potentially similar contamination removal using less water.

Supercritical water gasification (SCWG) can efficiently convert food waste to hydrogen-rich syngas without pre-dewatering. NaCl salt is the most common food additive and therefore inevitably accumulated in food waste. Though, the role of NaCl in SCWG of food waste is still unexplored. In this study, the influences of NaCl salt in food waste during SCWG on syngas production and corrosion of reactor material were investigated. The model food waste, representing food waste in China, with different NaCl contents (0–6 wt% dry basis) was gasified in supercritical water at 500 °C and autogenous pressure of ca. 28 MPa. The highest total gas yield of 21.70 mol/kg and H₂ yield of 6.89 mol/kg were obtained in the case of 3 wt% NaCl. The corrosion test on Hastelloy C276 and stainless steel SS316L materials was conducted in supercritical water for 24 h with different NaCl concentrations. Hastelloy C276 showed better resistance to corrosion in supercritical water than stainless steel 316L. However, when NaCl was involved in the reaction, large oxides grains of NiFe₂O₄, FeCr₂O₄, NiO, and Fe₃O₄ were observed on the surface of both materials.

Biofilm formation on food contact surfaces is a potential hazard leading to cross-contamination during food processing. We investigated Listeria innocua biofilm formation on various food contact surfaces and compared the washing effect of slightly acidic electrolyzed water (SAEW) at 30, 50, 70, and 120 ppm with that of 200 ppm of sodium hypochlorite (NaClO) on biofilm cells. The risk of L. innocua biofilm transfer and growth on food at retail markets was also investigated. The viability of biofilms that formed on food contact surfaces and then transferred cells to duck meat was confirmed by fluorescence microscopy. L. innocua biofilm formation was greatest on rubber, followed by polypropylene, glass, and stainless steel. Regardless of sanitizer type, washing removed biofilms from polypropylene and stainless steel better than from rubber and glass. Among the various SAEW concentrations, washing with 70 ppm of SAEW for 5 min significantly reduced L. innocua biofilms on food contact surfaces during food processing. Efficiency of transfer of L. innocua biofilm cells was the highest on polypropylene and lowest on stainless steel. The transferred biofilm cells grew to the maximum population density, and the lag time of transferred biofilm cells was longer than that of planktonic cells. The biofilm cells that transferred to duck meat coexisted with live, injured, and dead cells, which indicates that effective washing is essential to remove biofilm on food contact surfaces during food processing to reduce the risk of foodborne disease outbreaks.

Salmonella is one of the main foodborne pathogens that affect humans and farm animals. The Salmonella genus comprises a group of food-transmitted pathogens that cause highly prevalent foodborne diseases throughout the world. The aim of this study was to appraise the viability of Salmonella Typhimurium biofilm under water treatment at room temperature on different surfaces, specifically stainless steel (SS), plastic (PLA), rubber (RB), and eggshell (ES). After 35 D, the reduction of biofilm on SS, PLA, RB, and ES was 3.35, 3.57, 3.22, and 2.55 log CFU/coupon without water treatment and 4.31, 4.49, 3.50, and 1.49 log CFU/coupon with water treatment, respectively. The dR value (time required to reduce bacterial biofilm by 99% via Weibull modeling) of S. Typhimurium without and with water treatment was the lowest on PLA (176.86 and 112.17 h, respectively) and the highest on ES (485.37 and 2,436.52 h, respectively). The viability of the S. Typhimurium on ES and the 3 food-contact surfaces was monitored for 5 wk (35 D). The results of this study provide valuable information for the control of S. Typhimurium on different surfaces in the food industry, which could reduce the risk to consumers.