Electrically Charged Water Could Make Your Food Safer

Safer tomatoes?: A new technique uses electrically charged water to eliminate pathogens from produce. Image by Pluma.Safer tomatoes?: A new technique uses electrically charged water to eliminate pathogens from produce. Image by Pluma.

Food borne illnesses are a major drain on global economic and public health systems while also causing extreme discomfort and occasionally death in those afflicted. In the United States, over a fifth of reported food-derived illnesses arise due to contaminated fresh produce. To alleviate this, most produce sold is cleaned using relatively unpleasant solvents like peroxides or chlorine solutions. Now researchers report a new environmentally friendly method of destroying pathogens on the surface of food using that most benign of solvents, water!

Fresh fruits and vegetables are extremely vulnerable to contamination throughout their journey from farm to table. Harvest, processing, transportation, distribution and preparation are all stages at which pathogens can find their way onto the surface of the produce – from contaminated water or infected workers; from birds, insects or animals; and from improperly cleaned preparation surfaces. Because produce is frequently served raw, it does not have the additional safety net of thorough cooking. As a result, surface decontamination of produce is a key measure in preventing disease outbreaks. This is carried out through a variety of means including mild bleach solutions, chlorine dioxide, peracetic acid, hydrogen peroxide, ozone gas, and irradiation. Each of these, however, possesses certain drawbacks such as chemical residues, environmental concerns, visible damage, or incompatibility with “organic” regulations.

Now, scientists out of Harvard University report a new, more sustainable method for inactivating bacteria that overcomes many of these hurdles. The method relies on electrospraying water. Electrospraying is a common technique for generating fine aerosols wherein a very high voltage is applied to a liquid in a capillary tube. When the voltage is sufficiently large, the liquid erupts from the end of the tube as a fine spray of electrically charged nanodroplets.

Electrospraying: an old technique finds new application in food decontamination.Electrospraying: an old technique finds new application in food decontamination.

This becomes relevant to the food industry because highly charged water droplets possess a significant concentration of reactive oxygen species; that is, unstable oxygen-containing molecules. These oxygen species are already known to interact with and inactivate bacteria upon contact through oxidation and destruction of their outer cell membrane. In the newly published study, three common pathogens – Escherichia coli, Salmonella enterica, and Listeria innocua – were deposited on tomatoes and then sprayed with the charged nanowater. In each case, a notable decrease (between 80 and 98 %) in bacterial population was observed. Additionally, and importantly, preliminary studies have also shown that the electrosprayed water is harmless toward animals, even when inhaled in unreasonably large doses. Testing also concluded that the technique had no effect on either the taste or appearance of the food.

While still in the early testing stages, the electrospray technology needed to implement this method of produce sanitization is already well-established, making it a relatively small feat to expand this practice. In doing so, we will have a new chemical-free and environmentally-friendly method to ensure food safety – healthy eating on every level.