Evaluating roasting as a post-harvest step to reduce glyphosate residues in coffee beans via LC-MS/MS analysis

This study evaluates the degradation of glyphosate residues in coffee beans subjected to roasting, using a validated LC-MS/MS method. Green coffee beans were fortified with glyphosate at varying concentrations and roasted under medium and dark roasting conditions. Glyphosate was extracted with ultrapure water under agitation, followed by dilution with methanol, refrigerated centrifugation to precipitate proteins, and filtration. The method achieved a limit of detection of 0.14 mg kg^-1 and a limit of quantification of 0.44 mg kg^-1, with recoveries ranging from 96.0% to 105.9%, and precision values below 16%. The roasting process effectively degraded glyphosate. Medium roast reduced residues by up to 59%, and dark roast by up to 74%. Kinetic evaluation revealed non-linear behaviour inconsistent with pseudo-first- or pseudo-second-order models, suggesting that complex mechanisms are involved in glyphosate degradation during thermal processing. These findings demonstrate that roasting significantly decreases glyphosate levels in contaminated coffee beans, and the validated LC-MS/MS method offers a reliable approach for residue monitoring in thermally processed food matrices.