Engineered Nanotech Turns Oregano Oil into Potent Bacteria Killer

Researchers say the answer to preventing contaminated food may lie in nanoengineering


Researchers say nanoengineering natural oils may be an effective way of eliminating bacteria in food. Source: Wayne State University

Contaminated produce often leads to foodborne illnesses, so finding effective new ways to prevent and control bacteria is crucial. Believe it or not, a group of researchers says one of the answers may lie in nanoengineering.

Currently, industrial washing in chlorine-filled water is the most common prevention strategy.  However, a team from Wayne State University is looking for new alternatives for combating bacteria in food; They’ve been exploring natural antimicrobials (i.e. plant essential oils derived from oregano, clove and thyme) to minimize bacterial contamination.  

But the key issue with these natural oils is their low solubility in water. Therefore, the researchers are working on formulating oil nanoemulsions in an attempt to increase the solubility of essential oils and boost their antimicrobial capabilities.    

Natural oils have antimicrobial qualities

“Much of the research on the antimicrobial efficacy of essential oils has been conducted using products made by mixing immiscible oils in water or phosphate buffered saline,” said Yifan Zhang, an assistant professor of nutrition and food science. “However, because of the hydrophobic nature of essential oils, organic compounds from produce may interfere with reducing the sanitizing effect or duration of the effectiveness of these essential oils. Our team set out to find a new approach to inhibit these bacteria with the use of oregano oil, one of the most effective plant essential oils with antimicrobial effect.”

Zhang teamed up with Sandro da Rocha, an associate professor of chemical engineering and materials science, to collaborate on the study. The team found that oregano oil was effective at combating common foodborne bacteria (E. coli O157, Salmonella and Listeria) in artificially contaminated lettuce. “We wanted to explore the possibility of a nanodelivery system for the oil, which is an area of expertise of Dr. da Rocha,” added Zhang.

Using nanoemulsions

Rocha advised the team use nanoemulsions. “My team felt the use of nanoemulsions would improve the rate of release compared to other nanoformulations, and the ability of the food grade surfactant to wet the surface of the produce,” he said. “We were able to reduce L. monocytogenes, S. Typhimurium, and E. coli O157 on fresh lettuce.  Former Ph.D. student Denise S. Conti, now at the Generics Division of the FDA, helped design the nanocarriers and characterize them.”

Although there’s still a lot of work ahead, the study proves that essential oil nanoemulsions can be used to for safety control purposes and potentially replace chemicals.

“Our future research aims to investigate the antimicrobial effects of essential oil nanoemulsions in various combinations, as well as formulate the best proportions of each ingredient at the lowest possible necessary levels needed for food application, which ultimately will aid in maintaining the taste of the produce,” added Rocha.