Effect of Spontaneous Fermentation on Pesticide Residues in Peppers: Dissipation Patterns and Processing Factors

The occurrence of pesticide residues in vegetables remains an important food safety concern, while their behavior during traditional fermentation is less well characterized. This study evaluated changes in pesticide residues during 35 days of spontaneous pepper fermentation. Ten commercial pepper samples were fermented using a traditional household-scale procedure, and pesticide residues and microbial populations were monitored throughout fermentation. A total of 120 pesticides were analyzed by liquid chromatography-tandem mass spectrometry, and processing factors (PFs) were calculated. Four pesticides, acetamiprid, boscalid, cypermethrin, and metalaxyl, were detected in seven of the ten fresh pepper samples. The concentrations of all detected pesticides decreased during spontaneous fermentation, although the magnitude of reduction varied considerably among compounds. Cypermethrin showed the greatest reduction, reaching 92.4% by day 21 (PF = 0.076), whereas acetamiprid and metalaxyl decreased by 56.6% (PF = 0.434) and 49.7% (PF = 0.503), respectively, by day 35. Boscalid showed comparatively greater persistence, with a 20% reduction (PF = 0.800) on day 35. Exploratory correlation analysis showed predominantly negative associations between pesticide concentrations and microbial counts. However, these findings should not be interpreted as evidence of a causal relationship with pesticide dissipation. The magnitude of dissipation varied among the detected pesticides and may also have been influenced by sample- and matrix-specific factors.