Vegetable surface structure may contribute to foodborne illness

March 23, 2016

A study published in PLOS One shows that the surface texture may impact the ability of pathogenic viruses to adhere to fresh produce. The University of Illinois researchers chose 24 of the most common salad vegetables in the United States and assayed them to see if there was any relationship between the morphology and chemistry of the leaf or fruit surface and the adherence of viral particles, before and after a washing treatment.

They inoculated leafy salad greens and tomatoes with a swine virus that mimics human rotavirus, a common pathogen responsible for diarrhea, vomiting, fever, and abdominal pain. After exposing the vegetable surfaces to the virus, the researchers rinsed the vegetables twice with a standard saline solution.

The researchers found a thousand-fold difference in the number of viral particles adhering to different types of leafy greens and tomatoes. Vegetables with three-dimensional crystalline wax structures on the leaf cuticle harbored significantly fewer virus particles after rinsing. This was counterintuitive, as it was expected that small virus particles could “hide” in the rough structures of these cuticles. But, when the wax completely covers the surface, it becomes totally hydrophobic, which renders the whole leaf surface harder for viruses to attach to.

“The information from this study can be used down the road to select or breed for varieties that might have the capacity to reduce adherence of these particles,” said study author Jack Juvik, geneticist at the University of Illinois.

The researchers have already repeated the study using the bacterium E. coli, but they plan to look at even more vegetable varieties and pathogens in future studies.