LC–MS/MS Tracks Glyphosate in Coffee Beans

Glyphosate is the world's most widely used weedkiller, and it can be taken up by plants it was not meant for, potentially changing their chemical makeup. Coffee, the second most popular drink in the world, depends on glyphosate to keep crops productive. Yet little is known about whether coffee plants absorb glyphosate sprayed on the soil, whether it makes its way into the beans, and whether it changes their chemistry. To find out, researchers in Brazil tested how different ways of applying glyphosate affected the two main types of coffee, Arabica and Robusta. They tried seven different approaches, varying the type of sprayer nozzle and how often and when the weedkiller was applied over the growing season. They then used liquid chromatography–tandem mass spectrometry (LC–MS/MS) to measure how much glyphosate ended up in the beans, along with ultrahigh pressure liquid chromatography coupled with a photodiode array detector (UHPLC-PDA) to determine the beans' moisture, mineral content, and how much could be dissolved when brewed, as well as levels of caffeine and chlorogenic acids, natural compounds that contribute to coffee's flavor and health benefits. Their findings were published in the journal Food Research International.¹

How Does Glyphosate Work, and Why Might It Affect Coffee?

Glyphosate is a weedkiller that spreads throughout a plant no matter where it is first absorbed. It works by blocking a key enzyme that plants (and some microbes) need to make three important protein building blocks: phenylalanine, tyrosine, and tryptophan. These building blocks are vital for plant growth and for producing natural defense chemicals, including a group of compounds called phenolics. The process works like an assembly line, with simple starting materials converted step by step into a compound called chorismate, which is then turned into these three building blocks. Glyphosate shuts down one of the steps along the way, halting the whole line. This matters for coffee because one of the building blocks, phenylalanine, is the starting point for making chlorogenic acids, the natural compounds that contribute to coffee's flavor and health benefits.^2-5

Does Glyphosate End Up in Coffee Beans, and Does It Change Them?

The results showed that coffee plants do absorb glyphosate and that it can make its way into the beans, though only in small amounts (up to 0.5 mg per kilogram). Spraying in October and December left lower levels in the beans than schedules that continued into February, and these levels were not meaningfully different from those in plants that were not sprayed at all. Surprisingly, the weedkiller did not affect the levels of chlorogenic acids in the beans. Apart from a few minor one-off differences, none of the other qualities measured were significantly affected by glyphosate use either.¹

“These findings were supported by PCA (Principal Component Analysis) and PERMANOVA (Permutational Multivariate Analysis of Variance),” write the authors of the paper,¹ “which revealed that sample discrimination was influenced exclusively by species and crop year.” More research, in the opinion of the researchers, is needed to look at other compounds in coffee beans, especially with food safety in mind, to get a fuller picture of how glyphosate affects them.¹

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References

1. de Souza Costa, A. M.; Virginio, H. A.; de Azevedo Rincon, M. F. et al. Impact of Glyphosate Management Techniques on Residue Levels and Chemical Composition of Coffea arabica and Coffea canephora Beans. Food Res Int. 2026, 244, 120568. DOI: 10.1016/j.foodres.2026.120568
2. de Oliveira, M. D.; Araújo, J. O. et al. Targeting Shikimate Pathway: In silico Analysis of Phosphoenolpyruvate Derivatives as Inhibitors of EPSP Synthase and DAHP Synthase. J Mol Graph Model. 2020, 101, 107735. DOI: 10.1016/j.jmgm.2020.107735
3. Duke, S. O. The History and Current Status of Glyphosate. Pest Manag Sci. 2018, 74 (5), 1027-1034. DOI: 10.1002/ps.4652
4. Fuchs, B.; Saikkonen, K.; Helander, M. et al. Legacy of Agrochemicals in the Circular Food Economy: Glyphosate-based Herbicides Introduced via Manure Fertilizer Affect the Yield and Biochemistry of Perennial Crop Plants During the Following Year. Chemosphere 2022, 308 (Pt 2), 136366. DOI: 10.1016/j.chemosphere.2022.136366
5. Tzin, V.; Galili, G. New Insights into the Shikimate and Aromatic Amino Acids Biosynthesis Pathways in Plants. Mol Plant. 2010, 3 (6), 956-972. DOI: 10.1093/mp/ssq048