A novel antimicrobial technology to enhance food safety and quality of leafy vegetables using engineered water nanostructures

Authors: HUANG, RUNZE - Harvard University; VAZE, NACHIKET - Harvard University; SOORNEEDI, ANAND - University Of Massachusetts, Amherst; MOORE, MATTHEW - University Of Massachusetts, Amherst; Luo, Yaguang - Sunny; POVERENOV, ELENA - Agricultural Research Organization, Volcani Center; RODOV, VICTOR - Agricultural Research Organization, Volcani Center; DEMOKRITOU, PHILIP - Harvard University

Submitted to: Environmental Science: Nano
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2020
Publication Date: 12/23/2020
Citation: Huang, R., Vaze, N., Soorneedi, A., Moore, M., Luo, Y., Poverenov, E., Rodov, V., Demokritou, P. 2020. A novel antimicrobial technology to enhance food safety and quality of leafy vegetables using engineered water nanostructures. Environmental Science: Nano. 8:514-526. https://doi.org//10.1039/D0EN00814A.
DOI: https://doi.org/10.1039/D0EN00814A

Interpretive Summary: Pathogen contamination to food products poses significant threats to public health and the financial well being of the industry. Chemical anti-microbial agents used to reduce pathogen populations often leave undesirable chemical residues. In this study, we report a novel strategy to inactivate harmful bacteria on baby spinach leaves using engineered water nanostructures with trace amount of food grade chemicals that leave no residuals. Findings benefit fresh produce growers and processors with new technologies to improve food safety while maintaining quality.

Technical Abstract: Pathogen contamination of leafy vegetables has become a major public health issue worldwide. Current food safety practices to mitigate microbial contamination involve washes and sprays with chemical disinfectants, which result in chemical residues on the produce and generation of potentially toxic byproducts. Here, we report a novel, “dry”, nano-aerosol based, antimicrobial technology using engineered water nanostructures (EWNS) for leafy vegetable disinfection. These EWNS based nano-sanitizers are synthesized using a combined process of electrospray and ionization of aqueous solutions of nature-derived active ingredients (AIs). Such EWNS based nano-sanitizers have unique physico-chemical properties. They are highly mobile due to their nanoscale size and possess surface electric charge. The surface electric charge can be used to direct EWNS nano aerosol to the surface of interest where they can interact and inactivate microorganisms with minuscule amounts (nanogram level) of AIs. Here, EWNS based nano-sanitizers were synthesized using an AI cocktail (10% hydrogen peroxide, 1% citric acid, 0.1% lysozyme and 0.0025% nisin), and their efficacy against foodborne pathogen surrogates and spoilage microorganisms was assessed on a leafy vegetable model, namely spinach. It was shown that a 2-min exposure of EWNS based nano-sanitizers significantly (P < 0.05) reduced cell populations of Escherichia coli, Listeria innocua, and Pseudomonas fluorescens, on spinach by 3.5, 1.2 and 2.6 log, respectively. EWNS also reduced Penicillium italicum spores by 1 log in 15 minutes and bacteriophage MS2 by1.4 log in 5 minutes. More importantly, the estimated delivered dose of AIs using the EWNS approach was minuscule (258 pg/cm2 for a 15-minute exposure). No significant difference (P > 0.05) in color or surface pH of spinach was found after 15 minutes of exposure. In summary, EWNS based nano-sanitizers are highly effective against foodborne pathogens and spoilage microorganisms using only nanograms of nature-derived active ingredients and without an impact on produce quality.