Comparative antibacterial activities of neutral electrolysed oxidising water and other chlorine-based sanitizers (NaClO and ClO2):

Article published in science journal Nature in December 2019. To access the full article click: https://www.nature.com/articles/s41598-019-56248-7

Background

Microbial contamination of fresh produce such as spinach, lettuce, parsley and other leafy greens by opportunistic and human pathogens continues to be a major source of foodborne illnesses and disease outbreaks worldwide. In most instances, pre-harvest water such as irrigation water and post-harvest washing water have been identified as the main sources of contamination associated with human illness. Current water disinfection processes involve either the use of chemicals (such as chlorine, ozone, peracetic acid, or hydrogen peroxide), or non-chemical disinfection methods such as ultraviolet irradiation and membrane filtration. However, these treatment technologies all have shortcomings in terms of efficacy and/or safety concerns. Consequently, there is a growing global focus on the deployment of safe, effective and environmentally-sustainable irrigation water and post-harvest sanitation technologies.

Studies investigating EOW treatment of aqueous human pathogen suspensions under varying conditions of exposure time, pH, temperature, available chlorine, and redox potential have consistently shown substantial log reductions in viable microorganism. Of the various types of EOW, neutral EOW has been considered the most promising as it contains predominantly HOCl (hypochlorous acid), which is more effective than ClO− (hypochlorite) for microbial cell wall penetration and oxidative attack. However, there are limited published applications of neutral EOW use in the irrigation and washing of fresh vegetables or fruit, with publications to date mainly focussing on its use in the seafood and meat industries.

Bacteria used in the study E.coli (and a bioluminescent species used also), Listeria innocua, Salmonella enteritidis.

Summary of results

At 3mg/L (3ppm/0.0003%) free active chlorine, neutral EOW consistently inhibited growth of test bacteria. EOW treatment of the mixed bacterial suspension at low doses (<1mg/L) resulted in substantial 4-6 Log reduction (99.99-99.9999, that’s a reduction between 10,000-1,000,000) in viable counts (CFU/ml) of all bacteria tested.

Analysis confirmed hypothesis that the activity of EOW compares favourably with the equivalent concentrations of other chlorine-based sanitisers. NaClO (sodium hypochlorite) and EOW treatment gave same results whereas ClO2 (chlorine dioxide) did not perform as well in case of L. innocua and mixed bacterial culture.

EOW is still strongly inhibitory in the presence of increasing organic matter when their starting concentration was set at 5mg/L free available chlorine.

It is widely reported in literature that chlorine-based sanitisers have the propensity to induce the viable but not culturable state (VBNC) in bacteria (refers to bacteria that are in a state of very low metabolic activity and do not divide, but are alive and have the ability to become culturable once resuscitated) use of sanitisers at concentrations lower than the effective concentration could result in dissemination/transfer of VBNC cells which can then resuscitate and lead to outbreaks of food-borne disease. Basically this means that chlorine based disinfectants do not always completely kill bacteria.

Bioluminescent E.coli was used here and no metabolic activity was observed in the range of EOW and NaClO concentrations at which no growth was observed. Efficacy of EOW was slightly superior to NaClO, minimum in inhibitory concentrations for NaClO was 50mg/L and for EOW was 20 mg/L. ClO2 was very poor at this and showed little to no effect in the presence of organic matter.

What this is saying is that electrolysed water at 20ppm is as effective as sodium hypochlorite at 50ppm, so it is more potent. Coupled with the fact that neutral pH electrolysed water is easier and safer to handle and store – it is a powerful argument for using products like Electrox instead of traditional disinfectants which contain large quantities of harsh chemicals and have a very high pH, making them more hazardous to use and store.

Decontamination of aerosolised bacteria from a pig farm environment using a pH neutral electrochemically activated solution (Ecas4 anolyte)

To access the full article click: https://www.ncbi.nlm.nih.gov/pubmed/31553747

Background

ECAS4 Anolyte is the name of the electrolysed water in Australia, created using the same machinery and process as Electrox Sterilising Water here in the UK.

Bacterial and/or viral respiratory diseases are a major economic cost for pork production systems. Prevalence of swine respiratory diseases are influenced by interaction of multiple factors such as the aetiological microorganisms, environmental factors of the farm such as temperature and moisture or the presence of particulate matters and ammonia, and management factors such as animal density, vector control, and disinfection strategies. The level of production losses varies depending on the causative agents involved and their virulence. Bacterial pathogens, such as Actinobacillus pleuropneumoniae, may cause chronic or acute respiratory disease requiring prophylactic and/or metaphylactic antimicrobial use for adequate control. Cleaning and disinfection of the animal’s environment, in conjunction with quarantine, vaccination and antibiotic treatment, constitute an important component of prevention and control of respiratory diseases. In association with vaccination and the use of antibiotics, the prevention of porcine respiratory disease complex has been achieved by man- aging the environmental stressors through usage of disinfectants such as sodium hypochlorite, hydrogen peroxide, chlorine dioxide, formaldehyde, quaternary ammonium compounds, peroxyacetic acid and iodophors. While all these chemicals are very effective in reducing microbial load, there are limitations including differential effectiveness against a variety of bacteria, co-selection of antibiotic resistance, corrosiveness, concerns with skin irritation, and cross resistance to other disinfectants and antibiotics.

Method

50% electrolysed concentration was made up (150ppm) and generated a fog containing 0.75mg/m3. Fogged for 3 mins at 30 min intervals for 5 hours and air samples taken before, after and every hour. This was done in 7, 145m³ pig sheds.

Summary of results

Preliminary tests showed concentrations of 1.17ppm and 2.34pmm effective in killing A. pleuropneumoniae and MRSA respectively within 30 seconds of exposure. The table below shows that there was an almost 100% reduction in bacteria after the fogging cycle was completed.

Table 4. Total bacteria and Log10 reduction on air samples collected from an empty weaning room during Ecas4 anolyte fogging. Data reported as mean ± SEM, n - 4.
Samples	Total Bacteria (Log10 CFU/m2)	Log10 reduction	Percent reduction
Before fogging (0)	5.77 ± 0.01
1 h after fogging	5.10 ± 0.02	0.67	78.326
2 h after fogging	4.43 ± 0.05	1.34	97.361
3 h after fogging	3.49 ± 0.07	2.28	99.459
4 h after fogging	2.98 ± 0.03	2.79	99.837
5 h after fogging	0.65 ± 0.07	5.12	99.998

Since the Ecas4 anolyte is biodegradable, certified “organic” and requires extremely short downtime during the fogging period, it could potentially lead to a reduced use of prophylactic antibiotics for the prevention of porcine respiratory disease complex by minimising the trans mission of respirato ry pathogens such as A . pleuropneumoniae between carrier and naïve animals, and thus minimising the risk of development of antibiotic resistance, without the problems as sociated with the use of other chemicals such as formaldehyde and H2O2. Moreover, the levels of chlorine in the farm’s environment at 0.25ppm (0.75mg/m 3 of hypochlorous acid) would fall within the short term exposure limit (0.5 ppm) and the time weighted average limit (1.0 ppm) prescribed by the Safe Work Australia standards. This mea ns that at these concentrations it more than meets regulations for short term exposure.

Efficacy evaluation of a new water sanitizer for increasing the shelf life of Southern Australian King George Whiting and Tasman ian Atlantic Salmon fillets

For full article click: https://www.ecoloxtech.com/pdf/research/seafood/efficacy

Background

Food spoilage represents a growing economic concern world wide, with approximately one third designated for human consumption being lost or wasted annually, particularly in medium and high income countries. Additionally, it has been estimated that approximately 30% of people living i n the developed world are experiencing foodborne diseases (at different levels) each year. A thorough understanding of the biology of food spoilage organisms (particul arly in seafood) is critical to the development of ways to prolong product shelf life as well as for quality management systems in the food industry. Concerns regarding the spread of pathogenic and spoilage bacteria in foods and food production environment, coupled with limitations associated with existing biocides contin ue to drive the development of novel sanitizing methods.

Results

The shelf life of KGW fillets traditionally washed with tap water is less than 3 days when stored at 4^oC, similar to the shelf life of sea bream fillets stored at 5^oC while the shelf life of TAS fillets washed with tap water is less than 7 days. However, our results indicate that the use of 15% and 50 % E CAS4 solution (which is made using the same machinery and process as Electrox Sterilising Water) along the production line of KGW fillets significantly extended the sh elf life of the KGW fillets by 2 days. Similarly, TAS fillets treated with either 15% or 50% ECAS4 water had a significant extension of shelf life by 4 days. This extension is mo st likely due to the significant reduction on the initial bacterial populations as a result of the antibacterial activity exerted by the ECAS4 solution.

Importantly, a detailed blinded sensory assessment on cooked KGW and TAS fillets treated with 15% and 50% at 3 days post treatment showed no detectable difference in organoleptic qualities in comparison to freshly cut fillets washed with the control (tap water).