Traditional fruit cleaning methods may not be enough to completely eliminate pesticides, according to a new study published in Nano letters. Researchers have developed an innovative technique to detect the presence of pesticides at extremely low levels, challenging the effectiveness of traditional washing methods in ensuring food safety.

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The study focuses on a method called surface-enhanced Raman spectroscopy (SERS), which is used to identify traces of pesticides on agricultural products. This technique uses metallic nanoparticles to amplify signals from molecules exposed to a laser beam, enabling the detection of tiny amounts of chemical compounds. The team, which includes Dongdong Ye, Ke Zheng and Shaobo Han, developed a metal-coated membrane that can be applied to fruits and vegetables to detect pesticides. Tests showed that this membrane can identify pesticide residues not only on the surface of fruits, but also under the peel and in the outer layers of the pulp. The researchers first applied pesticides to apples and then washed them as a normal consumer would. Using their SERS membrane, they were able to detect the pesticides despite the low concentrations present. The results showed that even after washing, pesticides remained in the peel and pulp of the apples. Therefore, they suggest that to minimize the risk of ingestion, it would be necessary to peel fruits in addition to washing them.

This discovery has important implications for food safety. It suggests that while current fruit washing processes remove some contaminants, they may not be enough to fully protect consumers. In addition to apples, the SERS technique was also able to detect pesticide residues in other foods, such as cucumbers, shrimp, chili powder and rice.

Although the peel of fruits and vegetables contains valuable nutrients, peeling could reduce the risk of pesticide ingestion while avoiding digestive discomfort caused by certain insoluble fibers. The technology used in this study could be a valuable tool for scientists and health authorities to help them better understand the persistence of pesticides in food.