Development of a portable SERS tool to evaluate the effectiveness of washing methods to remove pesticide residue from fruit surface

Pesticides are commonly used to control pests and improve crop productivity in agriculture. Upon post-harvest, concerns have emerged regarding the potential harmful health effects resulting from the presence of pesticide residues. Analyzing these residues on crop surfaces is challenging due to their typically low concentration and potential interference from the complex matrix of the produce’s surface. To address this challenge, we developed a portable surface-enhanced Raman spectrometer (SERS)-based approach that offers a fast turnover rate, simplified protocol, on-site capability, and high sensitivity. Further, this new approach was used to investigate the efficacy of various washing methods to remove a fungicide (ferbam) from peach surfaces. Household washing methods were compared with the chlorine wash used in the food processing industry (25 mg/L, sodium hypochlorite). The 1- and 5-minute chlorine wash (25 mg/L) proved most effective in removing pesticide residues, compared to tap water, sodium bicarbonate, and vinegar-soaking methods. Among household washing agents, sodium bicarbonate and vinegar provided superior removal effectiveness compared to tap water. In addition, SERS analysis on the flesh and backside of the skin revealed negligible penetration of ferbam into peaches. This study not only introduces an innovative method for measuring pesticide residues but also contributes to our understanding of pesticide removal and penetration. This knowledge is crucial for the effective use of pesticides and mitigation of their exposure through food sources.