This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Following the major Cyclospora outbreak linked to iceberg lettuce, consumers might assume that produce labeled "triple-washed" offers greater protection from foodborne illness. But industrial washing cannot necessarily eliminate pathogens already established on produce.
At the same time, the disinfectants used during processing may react with the food itself, creating new compounds whose effects on human health are not yet fully understood. That hidden chemistry is the focus of research led by Adam Simpson, assistant professor in the Sonny Astani Department of Civil and Environmental Engineering at the USC Viterbi School of Engineering. "Food processing is an engineered unit process, similar to processes in heavy industry," Simpson said.
"If we manipulate the matrix, we may transform its chemical groups and incorporate chemicals into the food." Food safety testing commonly looks for known contaminants, such as pesticides or PFAS, on a food's surface or within its tissues. Simpson instead investigates "transformation products": new compounds created when processing chemicals react with proteins, fats and other components of food. The organization of those components is known as the food matrix.
Its structure determines how a disinfectant enters the food, which molecules it encounters and what reactions follow. Simpson began studying these reactions during his doctoral research, examining triple-washed vegetables and the chlorinated water used to disinfect meat. He found that chlorine can alter amino acids and fats, forming compounds known as chlorotyrosines and fatty acid chlorohydrins.
Because these compounds can remain bound within proteins and fats until digestion, tests designed to detect dissolved contaminants or surface residues may miss them. In a recent study published in the Journal of Hazardous Materials, Simpson and his research team examined fatty acid chlorohydrins formed when tree nuts are bleached with sodium hypochlorite, the active ingredient in many chlorine-based disinfectants. They also tested the compounds' effects on cells.
The results identified a potential hazard to consumers. Researchers must still determine how the body metabolizes these compounds and whether these exposures cause long-term health effects. Through a pilot collaboration with the Southern California Center for Chronic Disease Research and Prevention, Simpson's lab is now working with Ana Claudia Maretti-Garcia, assistant professor of research medicine at the Keck School of Medicine of USC.
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