Direct Ozone Application for Commercial Produce Processing (FDA GRAS)

In 2008, AWPI performed trials at the University of Georgia for direct contact ozone treatment of lettuce to study its effectiveness in killing E. coli, Listeria monocytogenes, and Salmonella enterica spp. With ozone being FDA GRAS*, we felt the time had come to experiment with some commercial produce applications.

The results were impressive; more impressive than with chlorine disinfection, which, although typically considered the weapon of choice for produce, has its drawbacks:

  1. Chorine leaves carcinogenic residues.
  2. It dries the product and alters its taste.
  3. It damages the environment when rinse water is disposed of.
  4. It doesn’t kill as many pathogens as quickly, effectively, and safely as ozone.

There’s another problem with chorine disinfection: because the application methods used to treat produce can’t guarantee quick and complete surface contact, chlorine is often overused in actual practice, which further increases the environmental dangers, consumer health threats, and product degradation.

We solved the application problem in our trials by passing the lettuce through a patented application system that thoroughly coated the produce in a single pass. Even though the trial pitted our ozone treatment against a highly concentrated mix of E. coli, Listeria monocytogenes, and Salmonella enterica spp., we achieved a 99.95 percent kill rate.

The advantage of ozone treatment is that, after it’s finished killing germs more effectively than chlorine, it quickly turns into harmless oxygen, with no residues to damage the environment–or the people who eat the lettuce. In a separate study performed at the University of Georgia, we even saw indications that ozone may increase shelf life, rather than decreasing it.

*FDA GRAS: Ozone was declared “Generally Recognized as Safe” for direct food application by the Food and Drug Administration in 2001.

Download a PDF of the trial results.