Evaluation of Ph Neutral Electrochemically Activated Solution (ECAS): as a Sanitiser for Livestock Husbandry and Food Safety Applications

The agriculture production, animal farming, and food processing industries heavily depend on biocides to either reduce microbial load or inactivate microorganisms. These chemical biocides are associated with issues such as bacterial co-resistance to antibiotics, production of toxic residues, and reduced consumer acceptability. Electrolysed oxidising (EO) water, also termed electrochemically activated solution (ECAS) is an eco-friendly broad-spectrum biocidal agent. Among acidic, slightly acidic, and neutral pH forms of ECAS, the neutral type is preferred for its non-corrosiveness while still ensuring antimicrobial activity. In veterinary husbandry and shelled egg decontamination, ECAS is currently used in the form of a solution or spray wash. Therefore, in this thesis, the disinfection efficacy of an ECAS aerosol fogging regimen to decontaminate a pig farm environment and shell eggs was evaluated. Additionally, the effectiveness and impact of ECAS as a wash was assessed and compared to commonly used chemical agents for the sanitisation of ready-to-eat spinach leaves, including evaluation of organoleptic properties, shelf life, and nutritional attributes. In turn, this offered the possibility of exploring the effects of ECAS on spinach leaf microbiota composition, in comparison to peroxyacetic acid, a widely used, environmentally friendly sanitiser. The pig farm fogging experiment was conducted using optimised parameters for farm air sample collection and qPCR techniques that discern between live and dead bacteria. ECAS was fogged at 0.75 mg of free available chlorine (FAC) per cubic meter of air for 3 min every 30 mins, for 5 hours. A time-dependent total bacteria reduction was observed, with the population reduced by 78%, 97%, 99.4%, 99.8%, and 99.998% every hour until the fifth hour. For the shelled egg sanitisation and cuticle integrity experiment, ECAS at 150 mg/L FAC spray washing for 45 s and a fogging for 2 min achieved a complete inactivation of total bacteria and Salmonella Enteritidis; a similar reduction was also observed for sodium hypochlorite spray washes (45 s). Most importantly, however, ECAS spray and aerosol fog washing did not significantly affect the cuticle of the eggshell. In the spinach leaf sanitisation experiment, the effectiveness of ECAS (50 & 85 mg/L of FAC) and peroxyacetic acid (PAA) based sanitiser (50 mg/L of PAA) in reducing the total microbial load and the purposely inoculated non-pathogenic bacteria, and their effect on sensory attributes in comparison to that of tap water washing was assessed. All types of sanitising washes significantly reduced (p < 0.05) total bacteria and coliforms, keeping sensory characteristics above the acceptance level even after ten days of storage at 4ºC. The inactivation of purposely inoculated bacteria varied with the bacterial species and the type of sanitiser. Overall, ECAS (85 mg/L of FAC) showed greater efficacy in reducing Escherichia coli, and Listeria innocua than PAA. Furthermore, the PAA inactivation trends for these species suggested the induction of a viable but not-culturable state. All three types of sanitising wash significantly reduced S. Enteritidis, and the reduction for all three sampling days was higher for PAA. Microbiome profile using 16s rRNA amplicon sequencing showed that all treatment types did not affect the composition and structure of the autochthonous bacterial community, but storage time significantly reduced (p < 0.05) the heterogeneity of the identifiable bacterial species. Compared to other eco-friendly biocidal agents, ECAS could find increasing application in horticulture production, livestock farming and food safety due to its high antimicrobial efficacy and low production costs, as well as due to increasingly restrictive regulations on the use of chemical disinfectants and the change in consumer perception. In addition, the use of ECAS would reduce the use of chemical disinfectants and sanitisers, which may co-select for bacterial antimicrobial resistance and cause occupational safety and environmental issues through the generation of toxic residues.Thesis (Ph.D.) -- University of Adelaide, School of Animal and Veterinary Sciences, 202

Sustainable Environmental Solutions

This book collects research activities focused on the development of new processes to replace obsolete practices that are often highly invasive, unsustainable, and socially unacceptable.Taking inspiration from real problems and the need to face real cases of contamination or prevent potentially harmful situations, the development and optimization of ‘smart’ solutions, i.e., sustainable not only from an environmental point of view but also economically, are discussed in order to encourage, as much as possible, their actual implementation

Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року

Second International Conference on Sustainable Futures: Environmental, Technological, Social and Economic Matters (ICSF 2021). Kryvyi Rih, Ukraine, May 19-21, 2021.Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року