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Science · Health

Contaminants and food safety

The food-safety picture of coffee from farm to cup – mould toxins, pesticide residues, roasting contaminants, metals from machines, microbes in cold brew and fraud – and the limits EU and Swiss food law set.

Across the chain: Science

Source-checkedby Coffearium verification pass· Last source-checked 21 Oct 2026· Prepared with AI assistance· 15 sources (15 tier A)· Updated 21 Oct 2026
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Contents
  • In the EU, roasted coffee may contain at most 3.0 µg/kg ochratoxin A (OTA) and soluble coffee 5.0 µg/kg; green coffee has no maximum level.1
  • The Codex code of practice names OTA as the primary food-safety issue in green coffee production; it can form during drying, storage and transport.3
  • Roasting reduces OTA by 65–100%, depending on the process, according to the Codex code.3
  • EU pesticide law applies a default maximum residue level of 0.01 mg/kg where no specific level is set for a product.6
  • The German Federal Institute for Risk Assessment (BfR) found excessive lead release in one of three portafilter espresso machines tested, especially after descaling.9

What food safety means for coffee#

Coffee passes through many hands before it reaches the cup. At several points, unwanted substances can enter it or form in it. Food law calls these contaminants and sets limits for some of them.1

For coffee, the hazards fall into a few groups. Mould toxins can form on the farm and in storage.3 Pesticides are used while the crop grows.8 Roasting forms compounds such as acrylamide.5 Machines can release metals, and cold brew can carry microbes.9,12 Fraud adds cheaper material to the product.14

This entry follows these hazards along the chain and gives the limits authorities set. It describes what the rules and studies say; it gives no health advice. What a cup contains in general is covered in what’s in a cup of coffee.

1FarmPesticides applied 8 Fallen or heapedfruit: OTA risk 3 2ProcessingSlow drying: OTAfungi grow ataw 0.80–0.95 3 3Storage, transportRewetting andcondensation: OTA 3 Defects: more OTA 3 4RoastingOTA cut by 65–100% 3 Acrylamide forms 5 Fillers may beadded 15 5BrewingLead from somemachines afterdescaling 9 Cold brew: noheat step 12 Schematic, not to scale. Hazards shown where the sources place them; not a risk ranking.
  1. Farm. Pesticides are used at different stages of cultivation.8 Fruit collected from the ground or left in heaps raises the risk of ochratoxin A.3
  2. Processing and drying. Ochratoxin A-producing fungi grow while the coffee passes water activity 0.95 to 0.80; slow drying gives them time.3
  3. Storage and transport. Rewetting and condensation in containers favour mould again; defective beans and husk can hold more ochratoxin A than sound beans.3
  4. Roasting. Reduces ochratoxin A by 65–100%3 and forms acrylamide.5 Cheap fillers, where used, are added before or during roasting.15
  5. Brewing. Some portafilter machines released lead, especially after descaling.9 Cold brew is made without a heat step.12
Where each hazard arises or changes along the coffee chain, as the sources place it.3,5,8,9,12,15 Schematic, not to scale; not a risk ranking.

Mould toxins: ochratoxin A#

Ochratoxin A (OTA) is a toxin made by some moulds. The Codex code of practice for coffee calls it the primary food-safety issue in the production of green coffee.3 In coffee, only some Aspergillus species produce it.3

OTA forms before the coffee is roasted. The risk lies in the time drying coffee spends in the water-activity range where OTA-producing fungi grow, and again when dried coffee gets wet in storage or transport.3 The moisture and water activity entry explains the thresholds. Defective beans and husk sometimes contain more OTA than sound beans.3

Roasting breaks down much of it: 65–100%, depending on the roasting process.3 The EU sets maximum levels for roasted and soluble coffee, but not for green coffee.1 Swiss law sets the same values for roasted and soluble coffee.2

Pesticide residues#

Pesticides are used at different stages of coffee cultivation; insecticides are among the controls discussed for the coffee berry borer.8 Traces can remain on the green coffee. EU law sets a maximum residue level (MRL) for each pesticide in each product.6 Where no specific level is set, a default of 0.01 mg/kg applies.6

The limits for each product are listed in the EU pesticides database.7 Roasting and brewing can lower some residues. A 2022 review reports this for one insecticide, dinotefuran, from a single study.8

Compounds formed in roasting#

Roasting forms process contaminants such as acrylamide. The EU sets benchmark levels for it: 400 µg/kg for roast coffee and 850 µg/kg for instant coffee.5 The roasting contaminants entry covers how acrylamide, furans and polycyclic aromatic hydrocarbons form, and how roast degree shifts them.

Machines, capsules and metals#

Metal parts of coffee machines are in contact with hot water and coffee. The German Federal Institute for Risk Assessment (BfR) tested eight new machines in 2013. One of three portafilter espresso machines released large amounts of lead, especially after descaling.9

The BfR states that the EU has no legal limit for metals released from metal food contact materials.9 It recommends rinsing machines thoroughly after descaling.9

Capsules are another question. In a 2013 study, the French food safety agency ANSES compared capsule and pod coffee with drip-brewed coffee.10 It concluded that capsules did not substantially change earlier conclusions on exposure to chemical contaminants from coffee.10 The packaging entry covers capsule materials.

Microbes and cold brew#

A 2020 viewpoint article states that the roasting process and fresh, hot brewing usually minimise microbiological risk.12 It calls cold brew one of the few coffee beverages with some microbiological food-safety hazards.12

Cold brew is made without sterilising temperatures and typically has a pH above 4.6.12 The cold brew entry covers the hazards and the rules for cafés.

Fraud and authenticity#

Food fraud in coffee takes three main forms. A 2021 review lists mixing beans of two species of different value, adding other substances or foods, and mislabelling.14

Arabica (C. arabica) costs more than robusta (C. canephora), which creates an incentive to substitute one for the other.13 In Brazil, cheaper materials such as corn, barley, soybean or coffee husks have been used as fillers in roasted coffee.15 Laboratories detect them with chromatography, spectroscopy and DNA-based methods.14,15 The coffee oil entry explains the marker used for robusta.

Reference values#

Limits as opened on 21 October 2026; the legal text in force applies. µg/kg equals ppb (by mass); 0.01 mg/kg equals 10 µg/kg (our calculation).

Parameter Value Source
EU maximum level, OTA, roasted coffee beans and ground roasted coffee 3.0 µg/kg Reg. (EU) 2023/915, Annex I, 1.2.141
EU maximum level, OTA, soluble (instant) coffee 5.0 µg/kg Reg. (EU) 2023/915, Annex I, 1.2.151
EU maximum level, OTA, green coffee None set Reg. (EU) 2023/9151
Swiss maximum level, OTA, roasted coffee (beans or ground) / soluble coffee 3 / 5 µg/kg VHK, Annex 2 (as of 1 Feb 2024)2
OTA reduction by roasting 65–100%, depending on the process Codex CAC/RCP 69-20093
Water activity window for OTA-producing fungi during drying 0.80–0.95 Codex CAC/RCP 69-20093
EU acrylamide benchmark level, roast coffee / instant (soluble) coffee 400 / 850 µg/kg (performance indicators, not maximum levels) Reg. (EU) 2017/2158, Annex IV5
EU default MRL for pesticides where no specific MRL is set 0.01 mg/kg Reg. (EC) 396/2005, Art. 186
Lead release from metal food contact materials No legal EU limit; Council of Europe specific release limit 10 µg/kg food (recommendation) BfR9
Aluminium in capsule and pod coffee, 2013 French study 1–156 µg/l across the eight brands in the table; their average 67 µg/l; filter-coffee reference 78 µg/l ANSES11
Cold brew pH Typically above 4.6 Kwok et al. 202012
Detection limit for robusta in arabica by 16-O-methylcafestol ≈1% w/w Gunning et al. 201813
0123456µg/kg ochratoxin A (maximum level)EU: roasted coffee beansand ground roasted coffee3.01 EU: soluble(instant) coffee5.01 Switzerland: roastedcoffee, beans or ground32 Switzerland: solublecoffee52
Data table
µg/kg ochratoxin A (maximum level)Source
EU: roasted coffee beans and ground roasted coffee3.01
EU: soluble (instant) coffee5.01
Switzerland: roasted coffee, beans or ground32
Switzerland: soluble coffee52
Maximum levels for ochratoxin A in coffee products in the EU (Regulation (EU) 2023/915) and Switzerland (VHK, as of 1 February 2024). The EU sets no level for green coffee; the Swiss rows read for this entry cover roasted and soluble coffee only.1,2 Acrylamide benchmark levels (400 and 850 µg/kg) are a different kind of value and are charted in the roasting contaminants entry.5

Ochratoxin A in detail#

Where it arises. The Codex code describes favourable conditions for OTA-producing fungi during drying.3 In storage, moisture can come from damp floors and walls; dried coffee must be protected from rewetting.3 Temperature changes during transport can cause condensation of the remaining water.3 In lower-grade coffee, fruits with black and sour defects contained the highest OTA levels.3 The drying, moisture and water activity, microorganisms and hulling and dry milling entries give the control points in detail.

What authorities say. In its 2020 opinion, the European Food Safety Authority (EFSA) states that OTA causes kidney toxicity in several animal species and kidney tumours in rodents.4 OTA is genotoxic in vitro and in vivo, but the mechanisms are unclear.4 For tumours, the margins of exposure would indicate a possible health concern if genotoxicity is direct.4 EFSA describes the uncertainty as high and notes that the risk may be overestimated.4 The opinion covers all foods; its abstract does not give coffee’s share of exposure.4

Limits. EU Regulation 2023/915 sets 3.0 µg/kg for roasted beans and ground roasted coffee and 5.0 µg/kg for soluble coffee.1 No entry names green coffee.1 The Swiss ordinance on contaminants (VHK) lists 3 µg/kg for roasted coffee and 5 µg/kg for soluble coffee.2

Pesticide residues in detail#

The EU framework. Regulation (EC) No 396/2005 requires that products in its Annex I do not exceed the MRLs set in Annexes II and III.6 Where no specific MRL is set, 0.01 mg/kg applies.6 According to the Finnish Food Authority, MRLs are set by the European Commission based on opinions of EFSA, and are listed in the EU pesticides database.7 No coffee-specific MRLs were looked up in the database for this entry.

What studies report. A 2022 narrative review states that studies have found pesticides in commercial coffee after processing.8 It cites a study in which roasting at 230–240 °C for 12–14 min lowered dinotefuran by 62.2–100%.8 The same study reports further losses of dinotefuran on brewing.8 The review tabulates EU MRL exceedances in green coffee samples from one study, for example diazinon in 11 samples; it gives the size of that sample set inconsistently (118 and 181).8 These are single-study findings, not monitoring results.

No EU-wide monitoring results for coffee were opened for this entry. Swiss pesticide residue rules were not checked.

Metals from machines and capsules#

Lead. In the BfR’s 2013 tests of eight new machines, one of three portafilter espresso machines released large amounts of lead, especially after descaling.9 The BfR considers it possible that acidic descalers release lead from metal components, and states that the source of the lead is unknown.9 It refers to a Council of Europe resolution with a specific release limit of 10 µg of lead per kg of food, a recommendation rather than law.9 Its advice is to rinse thoroughly after descaling and run water through before preparing coffee.9 The BfR does not name products.9

Capsules. The 2013 ANSES study tested ten brands of capsules against drip-brewed coffee.10 Average levels of cobalt, chromium, tin, nickel, copper, zinc and acrylamide were slightly higher with capsules, but of the same order of magnitude; aluminium was not among them.10 In the data table, aluminium ranged from 1 to 156 µg/l across eight brands, against 78 µg/l in the filter-coffee reference.11 No phthalates or bisphenol A were detected.10 Furan was detected in all samples, but no conclusion could be drawn.10

Microbiological hazards#

A 2020 viewpoint article states that roasting and fresh, hot brewing usually minimise microbiological risk in coffee.12 Cold brew differs: it is made without sterilising temperatures, and its pH, typically above 4.6, does not effectively suppress microbial growth.12 Citing a summary of challenge studies that is based on personal communications with industry, the article reports that Salmonella, Listeria monocytogenes and Escherichia coli may stay viable in cold brew for 7–28 days; the underlying studies are not named.12 It states that ready-to-drink products under anaerobic conditions must be controlled, by pH or thermal processing, to mitigate the risk of Clostridium botulinum, and the authors recommend that cold brew be considered specifically in HACCP systems.12 It also expects pesticides or mycotoxins in cold brew when the raw beans are contaminated.12 The cold brew entry gives the US rules for cafés.

Authenticity testing#

Robusta in arabica. A 2018 study found 16-O-methylcafestol (16-OMC), long used as a robusta marker, in arabica roast coffee for the first time.13 The authors note that the presumed absence of 16-OMC from arabica underpins the DIN 10779 method.13 With their method they reached a detection limit of about 1% w/w robusta in arabica.13 The coffee oil and green coffee composition entries cover the chemistry.

Fillers. A 2018 review of chromatographic methods names corn, soybean, barley, rye, caramel and coffee husks as the most commonly used adulterants in Brazil.15 It reports that adulterants are added before or during roasting, in concentrations of up to 40% (w/w) in roasted coffee sold in Brazil.15 According to the review, microscopy is the main technique for controlling the quality of Brazilian coffee, and ultra-performance liquid chromatography with tandem mass spectrometry is a recent trend for confirming fraud.15

Origin and other methods. A 2021 review covers chromatography, spectroscopy and single-nucleotide polymorphism (SNP) methods to tell arabica from robusta.14 It also describes methods to trace geographical origin and the practice of adding pharmacologically active compounds to coffee.14

Open questions#

  • Coffee’s share of OTA exposure. The EFSA abstract opened for this entry does not give the contribution of coffee; the full opinion was not read.
  • Pesticide residues in roasted coffee and the cup. Only one study on one insecticide, reported in a review, was available for this entry; no EU monitoring data for coffee were opened.
  • Metals from machines. The BfR tested eight machines in 2013 and did not identify the source of the lead; no larger survey was opened for this entry.
  • Allergens. No source opened for this entry addressed allergens in coffee.

Key studies#

Kwok et al., 2020 – Food-safety challenges of cold brew. A viewpoint article on roasting, extraction, flavour, contamination and food safety of cold brew. It contrasts hot-brewed coffee with cold brew, which lacks a heat step and typically has a pH above 4.6, and recommends considering cold brew specifically in HACCP systems.

Challenges 11(2), 26 · doi:10.3390/challe11020026

Gunning et al., 2018–16-OMC in arabica. Used low-field NMR and other methods on roast coffees and found 16-O-methylcafestol in arabica for the first time. This sets a floor of about 1% for detecting robusta in arabica with this marker.

Food Chemistry 248, 52–60 · doi:10.1016/j.foodchem.2017.12.034

de Carvalho Martins et al., 2018 – Fraud in commercial coffee. Reviews chromatographic methods for detecting fillers and species substitution, from 1958 to recent mass spectrometry. It lists the adulterants most used in Brazil and the stage at which they are added.

Food Quality and Safety · doi:10.1093/fqsafe/fyy017

Merhi et al., 2022 – Pesticides in coffee. A narrative review of pesticide use in coffee, detection methods and mitigation. It collects single studies on residues in green and processed coffee, including the loss of one insecticide on roasting and brewing.

Frontiers in Public Health 10, 1004570 · doi:10.3389/fpubh.2022.1004570

General information, not medical advice.

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Change log

  • – Cold brew pathogen survival (7–28 days) now attributed to a summary based on personal communications with industry and removed from the reference values table; Kwok et al. described as a viewpoint article; cold brew pH given as typically above 4.6. Reason: The cited article states this basis and wording; the number is not backed by named challenge studies.
  • – Codex statement narrowed to OTA as the primary food-safety issue in green coffee production; drying-risk sentence reworded to the time spent in the risk water-activity range. Reason: Matches the Codex code's wording (para. 9, 37).
  • – Pesticide review – removed the sample count (118) and the claim of the largest loss in brewing; microscopy described as the main technique in Brazil, not the standard method. Reason: Merhi et al. give the sample set as both 118 and 181 and report brewing losses without ranking them; de Carvalho Martins et al. call microscopy the main technique for Brazilian coffee.

Sources

  1. AEuropean Commission (2025). Commission Regulation (EU) 2023/915 on maximum levels for certain contaminants in food (consolidated text, 01.07.2025), Annex I, section 1.2. EUR-Lex.
  2. AEidgenössisches Departement des Innern (EDI) (2024). Verordnung des EDI über die Höchstgehalte für Kontaminanten (Kontaminantenverordnung, VHK), SR 817.022.15, Stand am 1. Februar 2024. Swiss federal law (read in the Lexaris legal database copy).
  3. ACodex Alimentarius Commission (FAO/WHO) (2009). Code of Practice for the Prevention and Reduction of Ochratoxin A Contamination in Coffee (CAC/RCP 69-2009). Codex Alimentarius.
  4. AEFSA Panel on Contaminants in the Food Chain (CONTAM); Schrenk, D.; Bodin, L.; Chipman, J. K.; et al. (2020). Risk assessment of ochratoxin A in food. EFSA Journal 18(5), 6113. doi:10.2903/j.efsa.2020.6113 · other copies
  5. AEuropean Commission (2017). Commission Regulation (EU) 2017/2158 of 20 November 2017 establishing mitigation measures and benchmark levels for the reduction of the presence of acrylamide in food. Official Journal of the European Union L 304, 21 November 2017 (EUR-Lex).
  6. AEuropean Parliament; Council of the European Union (2005). Regulation (EC) No 396/2005 of the European Parliament and of the Council of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin, Article 18 (original as adopted). Official Journal of the European Union L 70, 16 March 2005 (legislation.gov.uk copy, original as adopted).
  7. AFinnish Food Authority (Ruokavirasto) Pesticide residue regulation. Ruokavirasto.
  8. AMerhi, A.; Kordahi, R.; Hassan, H. F. (2022). A review on the pesticides in coffee: Usage, health effects, detection, and mitigation. Frontiers in Public Health 10, 1004570. doi:10.3389/fpubh.2022.1004570 · other copies
  9. AGerman Federal Institute for Risk Assessment (BfR) (2025). Some portafilter espresso machines release too much lead (FAQ, updated 7 May 2025). BfR.
  10. AFrench Agency for Food, Environmental and Occupational Health & Safety (ANSES) (2013). “Espresso” machine coffee pods and capsules do not increase exposure to chemical contaminants. ANSES (news item, 25 September 2013).
  11. AFrench Agency for Food, Environmental and Occupational Health & Safety (ANSES) (2013). Results of the study on chemical contaminants in coffee pods and capsules. ANSES (data table accompanying the 2013 study).
  12. AKwok, R.; Lee Wee Ting, K.; Schwarz, S.; Claassen, L.; Lachenmeier, D. W. (2020). Current Challenges of Cold Brew Coffee – Roasting, Extraction, Flavor Profile, Contamination, and Food Safety. Challenges 11(2), 26. doi:10.3390/challe11020026 · other copies
  13. AGunning, Y.; Defernez, M.; Watson, A. D.; Beadman, N.; Colquhoun, I. J.; Le Gall, G.; Philo, M.; Garwood, H.; Williamson, D.; Davis, A. P.; Kemsley, E. K. (2018). 16-O-methylcafestol is present in ground roast Arabica coffees: Implications for authenticity testing. Food Chemistry 248, 52–60. doi:10.1016/j.foodchem.2017.12.034 · other copies
  14. APérez Bosch, M.; Domínguez López, I.; López-Yerena, A.; Vallverdú i Queralt, A. (2021). Current strategies to guarantee the authenticity of coffee. Critical Reviews in Food Science and Nutrition. doi:10.1080/10408398.2021.1951651 · other copies
  15. Ade Carvalho Martins, V.; Godoy, R. L. de O.; Gouvêa, A. C. M. S.; Santiago, M. C. P. de A.; Borguini, R. G.; Braga, E. C. de O.; Pacheco, S.; Nascimento, L. da S. de M. do (2018). Fraud investigation in commercial coffee by chromatography. Food Quality and Safety (accepted manuscript). doi:10.1093/fqsafe/fyy017 · other copies

Tier A · authoritative · B · trade and expert · C · general. Supporting quotes for every source are in the data version of this entry. If a publisher’s site refuses access, try the doi link or “other copies”.

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