Neutral electrolyzed oxidizing water is effective for pre-harvest decontamination of fresh produce

• Published in: Food microbiology 2021-02, Vol.93, p.103610, Article 103610
• Main Authors: Ogunniyi, Abiodun D., Dandie, Catherine E., Brunetti, Gianluca, Drigo, Barbara, Aleer, Samuel, Hall, Barbara, Ferro, Sergio, Deo, Permal, Venter, Henrietta, Myers, Baden, Donner, Erica, Lombi, Enzo
• Format: Article
• Language: English
• Subjects: Baby spinach; Chlorine; Decontamination; Disinfection; Electrolysis; Electrolyzed oxidizing water; Food Microbiology; Foodborne Diseases - microbiology; Foodborne pathogens; Lactuca - microbiology; Lettuce; Listeria; Plant Leaves - microbiology; Plants - microbiology; Pre-harvest sanitization; Radioisotopes; RNA, Ribosomal, 16S; Sodium hypochlorite; Sodium Hypochlorite - chemistry; Spinacia oleracea - microbiology; Water - chemistry
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2020.103610

Pre-harvest sanitization of irrigation water has potential for reducing pathogen contamination of fresh produce. We compared the sanitizing effects of irrigation water containing neutral electrolyzed oxidizing water (EOW) or sodium hypochlorite (NaClO) on pre-harvest lettuce and baby spinach leaves artificially contaminated with a mixture of Escherichia coli, Salmonella Enteritidis and Listeria innocua (~1 × 108 colony-forming units/mL each resuspended in water containing 100 mg/L dissolved organic carbon, simulating a splash-back scenario from contaminated soil/manure). The microbial load and leaf quality were assessed over 7 days, and post-harvest shelf life evaluated for 10 days. Irrigation with water containing EOW or NaClO at 50 mg/L free chlorine significantly reduced the inoculated bacterial load by ≥ 1.5 log10, whereas tap water irrigation reduced the inoculated bacterial load by an average of 0.5 log10, when compared with untreated leaves. There were no visual effects of EOW or tap water irrigation on baby spinach or lettuce leaf surfaces pre- or post-harvest, whereas there were obvious negative effects of NaClO irrigation on leaf appearance for both plants, including severe necrotic zones and yellowing/browning of leaves. Therefore, EOW could serve as a viable alternative to chemical-based sanitizers for pre-harvest disinfection of minimally processed vegetables. •Electrolyzed oxidizing water (EOW) was used for pre-harvest produce sanitation.•Artificially-contaminated manure suspension was inoculated onto lettuce and spinach.•Irrigation with EOW-treated water at 50 mg/L of free chlorine reduced bacterial load.•EOW-treated water had no negative effects on leaf quality pre- and post-harvest.•In comparison, sodium hypochlorite irrigation showed leaf necrosis and browning.