Pesticides Under the Skin of Apples

 

Both pesticides and herbicides are used worldwide. These substances are used to ensure food security. However, they are a safety risk to people who ingest them. To protect human beings, devices are being created to search for even the tiniest trace amount of harmful substances.

A new article was written for Nano Letters. Researchers claimed to have created an imaging method to discern pesticide contamination at low levels. It’s use on fruit proves that the food safety applications are lacking and need improvement.

The method researchers used is called SERS Or surfaced enhanced Raman spectroscopy. It is a non-destructive way to detect chemicals on produce. SERS uses metal nanoparticles or nanosheets to amplify the signals produced by molecules exposed to the Raman laser beam. The creative patterns are sort of a molecular signature. The patterns can be used to pinpoint small amounts of specific substances.

Dongdong Ye, Ke Zheng, Shaobo Han other scientists have created a metal coated membrane that can be laid on top of farm grown produce. They wanted to develop the material to accommodate a wide variety of other applications.

The scientists began with a cellulose hydrogen film. It was stretched out to form nanoscale folds along its surface. The resulting membrane is highly flexible and almost transparent in light. These are both key features for SERS signal detection. 

During testing of the membrane, scientists sprayed the pesticides Thiram and carbendazim. They were used both alone and together on apples, dried and washed to mimic our every day practices.

When the membrane was laid over the apples, SERS detected pesticides on all the apples, even though the chemicals were at low volumes. The researchers were able to see scattered light signatures for each pesticide, and detect further contamination into the fruit’s peel and outermost layer of the pulp.  

Clearly, washing alone is insufficient to remove pesticides and peeling would be required to remove potential contamination. Researchers have studied not only apples, but cucumbers, shrimp, chili powder, and rice.