Plant extracts, essential oils, and organic sanitisers have all proved effective in killing bacteria on leafy greens and extending their shelf life. When emulsified in the water used to wash these leaves, the approach compares to (and sometimes even works better than) bleach or hydrogen peroxide.

“Plant antimicrobials can be used by consumers at home,” said Sadhana Ravishankar, associate professor at the University of Arizona’s School of Animal and Comparative Biomedical Sciences. “Plant extracts and essential oils can be added in the wash water by themselves or combined with vinegar in the wash water for treatment.”

Benefits of using plant antimicrobials and organic sanitizers are that they are natural, environmentally friendly, and less energy intensive since they are effective at both room and cold temperatures. They also continue to kill bacteria during storage; their effectiveness is not reduced in the presence of organic matter; and they have added health benefits linked to a reduction in the occurrence of cancer, diabetes, and high cholesterol. The wash water containing plant compounds and organic sanitisers can also be recycled and reused without a loss in effectiveness.

“We have also researched a new way of applying plant antimicrobials to improve salad safety,” said Ravishankar. “We have incorporated plant essential oils into edible films that are added into salad bags and the vapors from the oils kill the bacteria in the salad bags during storage. Edible films are also plant-based sources such as apples, carrots, hibiscus, or spinach pulp.”

The project team has been using social media as an educational tool for the benefit of growers and other stakeholders.  The social media campaign includes YouTube videos, Facebook, and Twitter.

The outcomes of this project will benefit consumers by reducing and preventing contamination of the leafy greens by foodborne pathogens at the production and harvesting levels, providing a safer product in stores and on their tables.

Moving forward, Ravishankar and her team are testing combinations of plant antimicrobials and the effectiveness of them when the wash water is recycled.  USDA’s National Institute of Food and Agriculture (NIFA) is funding this new research, a four-year, $2,907,354 Organic Agriculture Research and Extension Initiative (OREI) grant.

OREI seeks to solve critical organic agriculture issues, priorities, or problems by integrating research, education, and extension activities. OREI-fund projects that will enhance the ability of producers and processors who have already adopted organic standards to grow and market their high quality organic agricultural products.

NIFA invests in and advances agricultural research, education, and extension and seeks to make transformative discoveries that solve societal challenges.

Source: Kelly Flynn, National Institute of Food and Agriculture/USDA