Sanitizing effectiveness of commercial “active water” technologies on Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes

Optimization of Electrolysis Parameters for Green Sanitation Chemicals Production Using Response Surface Methodology

Electrolyzed water (EW) shows great potential as a green and economical sanitation solution for the food industry. However, only limited studies have investigated the optimum electrolysis parameters and the bactericidal effect of acidic electrolyzed water (AcEW) and alkaline electrolyzed water (AlEW). Here, the Box–Behnken experimental design was used to identify the optimum parameters. The tests were conducted with different types of electrodes, electrical voltages, electrolysis times, and NaCl concentrations. There were no obvious differences observed in the physico-chemical properties of EW when different electrodes were used. However, stainless steel was chosen as it meets most of the selection criteria. The best-optimized conditions for AcEW were at 11.39 V, 0.65 wt.% NaCl, and 7.23 min, while the best-optimized conditions for AlEW were at 10.32 V, 0.6 wt.% NaCl, and 7.49 min. The performance of the optimum EW (AcEW and AlEW) compared with commercial cleaning detergents for the food industry was then evaluated. The bactericidal activity of AcEW and AlEW was examined against Escherichia coli ATCC 10536 at different temperatures (30 °C and 50 °C) for 30 s. The results show that both AcEW and AlEW have the ability to reduce the Escherichia coli to non-detectable levels (less than 2 log CFU/mL).

Applications of Electrolyzed Water as a Sanitizer in the Food and Animal-By Products Industry

Food demand is increasing every year and, usually animal-derived products are generated far from consumer-places. New technologies are being developed to preserve quality characteristics during processing and transportation. One of them is electrolyzed water (EW) that helps to avoid or decrease the development of foodborne pathogens, or losses by related bacteria. Initially, EW was used in ready-to-eat foods such as spinach, lettuce, strawberries, among others; however, its application in other products is under study. Every product has unique characteristics that require an optimized application of EW. Different sanitizers have been developed; unfortunately, they could have undesirable effects like deterioration of quality or alterations in sensory properties. Therefore, EW is gaining popularity in the food industry due to its characteristics: easy application and storage, no corrosion of work surfaces, absence of mucosal membrane irritation in workers handling food, and it is considered environmentally friendly. This review highlights the advantages of using EW in animal products like chicken, pork, beef, eggs and fish to preserve their safety and quality.

Effect of electrolyzed water on enzyme activities of triticale malt during germination

Triticale malt can be used as a source of enzymes or as a raw material for the production of functional foods. In this study, triticale malt was produced by soaking triticale seeds either in tap water (TW) or slightly acidic electrolyzed water (SAEW) and then rinsing with TW, SAEW, or alkaline electrolyzed water (AEW). We determined the length of the hypocotyl of triticale malt and the activities of α-amylase, phytase, proteases, and lipase during 4 days of germination. The electrolyzed water (EW) treatments promoted the growth of triticale malt. On the 4th day of germination, the hypocotyl length of triticale malt soaked in TW and watered with SAEW was 24.57% longer than that of triticale malt soaked and watered with TW. The α-amylase, phytase, acidic protease, and lipase activities of triticale malt soaked in SAEW and watered with AEW were high on the 4th germination day (0.11, 1.24 × 10^-4, 0.62, and 0.51 units/mg protein, respectively). The main finding of this study is that the use of EW, especially during the soaking procedure, may be a promising way to obtain triticale malt with high enzyme activity for use in the production of functional foods.

Development of Portable Flow-Through Electrochemical Sanitizing Unit to Generate Near Neutral Electrolyzed Water

We developed a portable flow-through, electrochemical sanitizing unit to produce near neutral pH electrolyzed water (producing NEW). Two methods of redirecting cathode yields back to the anode chamber and redirecting anode yields the cathode chamber were used. The NEW yields were evaluated, including: free available chlorine (FAC), oxidation-reduction potential (ORP), and pH. The performances of 2 electrodes (RuO₂ -IrO₂ /TiO₂ and IrO₂ -Ta₂ O₅ /TiO₂ ) were investigated. The unit produced NEW at pH 6.46 to 7.17, an ORP of 805.5 to 895.8 mV, and FAC of 3.7 to 82.0 mg/L. The NEW produced by redirecting cathode yields had stronger bactericidal effects than the NEW produced by redirecting anode yields or NEW produced by mixing the commercial unit's anode and cathode product (P < 0.05). Electron spin resonance results showed hydroxyl free radicals and superoxide anion free radicals were present in the NEW produced by developed unit. The NEW generator is a promising sanitizing unit for consumers and the food industry to control foodborne pathogens.

PRACTICAL APPLICATION

Current commercial NEW-producing units are quite large and are not convenient for family using. The developed portable flow-through, NEW-producing unit has great potential in a wide range of applications, such as organic farm, households, and small food industries. The examined sanitizing treatments showed effective control of Escherichia coli O157:H7 and Listeria monocytogenes.

Metabolite profiling of Listeria innocua for unravelling the inactivation mechanism of electrolysed water by nuclear magnetic resonance spectroscopy

Bactericidal effects of low concentration electrolysed water (LcEW) on microorganisms are previously well reported; however, the inactivation mechanism of EW is not understood. The lethal and sublethal injuries of L. monocytogenes and L. innocua by EW treatments were determined and the metabolic profile changes for L. innocua were characterised using nuclear magnetic resonance (NMR). Microbial metabolomics approach combined with multivariate data analyses was used to interpret the cellular chemical fingerprints of L. innocua. The relative amount of intracellular reactive oxygen species (ROS) was assayed using 2',7-dichlorodihydrofluorescein diacetate (H₂DCFDA). The results showed that the proportion of the sublethally injured microbial cells L. monocytogenes and L. innocua increased from 40% to 70% and from 35% to 65%, respectively, when the free available chlorine (FAC) of LcEW increased from 2 to 8 mg/L. Overall, 36 low-molecular-weight metabolic compounds in L. innocua extracts were characterised by NMR spectroscopy. EW perturbation resulted in a drastic and multitude disruption across a wide range of biochemical process including peptidoglycan synthesis, nucleotides biosynthesis and amino acid metabolism. Elevated levels of α-ketoglutarate and succinate implicated the enhanced glutamate decarboxylase (GAD) system and γ-aminobutyric acid (GABA) shunt for the protection against oxidative stress. These findings provided the comprehensive insights into the metabolic response of Listeria to EW oxidative stress and can serve as a basis for better utilisation for sanitisation.

Application of electrolyzed water on reducing the microbial populations on commercial mung bean sprouts

The efficacy of acidic electrolyzed water (AEW) for reducing total bacteria, coliforms, yeast and mold counts on commercial mung bean sprouts was investigated. The impact of pH, available chlorine concentration (ACC) and the cleaning method on antimicrobial efficacy of AEW was studied. AEW with a pH of 4.47 reduced the total bacterial, coliform, and yeast and mold counts on mung bean sprouts by 1.23, 1.42 and 1.25 log CFU/g, respectively. The efficacy of AEW increased with increasing ACC, and further studies showed that its antimicrobial ability was based on a combination of pH and ACC values. Cleaning using ultrasonic waves enhanced the antimicrobial activity of electrolyzed water, achieving reduction of 2.46, 2.13 and 2.92 log CFU/g for total bacterial, yeast and mold, and coliform counts, respectively. These results have indicated that using ultrasonic waves as a cleaning method, combined with AEW, could be a promising way to reduce the microbial populations on mung bean sprouts.