In a peer-reviewed research paper from the American Chemical Society, researchers concluded that current food safety practices “may be insufficient” to prevent people from ingesting pesticides while eating fruits such as apples.
The researchers came to the conclusion after developing a high-tech analytical method called surface-enhanced Raman spectroscopy (SERS), which is a non-destructive method for detecting chemicals from modern farming on produce.
SERS uses metal nanoparticles or nanosheets to amplify the signals created by molecules when they are exposed to a Raman laser beam. The patterns created by the metal-enhanced scattered light serve as molecular signatures and can be used to identify small amounts of specific compounds.
Methodology
For the study, Dongdong Ye, Ke Zheng, Shaobo Han and their colleagues designed a metal-coated membrane they could lay atop farm-grown produce. They also wanted to develop the material to be versatile enough to accommodate an array of other applications.
The researchers started by stretching a cellulose hydrogel film to form aligned nanoscale wrinkles along its surface, before immersing the film in a silver nitrate solution to coat the grooves with SERS-enhancing silver nanoparticles.
The researchers then sprayed the pesticides thiram and carbendazim, alone or together, onto apples, air-dried the fruits and then washed them to mimic everyday practices. In addition, they used the SERS membrane system to detect pesticides on cucumbers, shrimp, chili powder and rice.
When they laid their membrane over the apples, SERS detected pesticides on the apples, even though the chemicals were present at low concentrations. The team was also able to detect pesticide contamination through the fruit’s peel and into the outermost layer of pulp.
‘Pesticide ingestion cannot be avoided by simple washing’
The researchers explained that the results suggest rinsing apples and other fruits before consumption could be insufficient to prevent pesticide ingestion and that peeling would be required to remove potential contamination in the skin and outer pulp.
“Food safety is vital to human health, necessitating the development of non-destructive, convenient, and highly sensitive methods for detecting harmful substances,” the paper said.
“Notably, the distribution of pesticides in the apple peel and pulp layers is visualized through Raman imaging, confirming that the pesticides penetrate the peel layer into the pulp layer. Thus, the risk of pesticide ingestion from fruits cannot be avoided by simple washing other than peeling.”
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