{ "id": "ochratoxin-a", "url": "https://coffearium.org/entries/ochratoxin-a/", "license": "CC-BY-4.0", "title": "Ochratoxin A", "summary": "Ochratoxin A (OTA) is a mould toxin that can form in coffee on the farm, during drying and in storage. This entry covers the moulds that make it, where it forms, how roasting and brewing change it, how it is tested and the EU limits.", "domain": "post-harvest-processing", "kind": "Concept", "stage": "process", "topics": [ "science" ], "topicSections": {}, "lang": "en", "status": "verified", "reviewer": "Coffearium verification pass", "lastVerified": "2026-10-21T00:00:00.000Z", "updated": "2026-10-21T00:00:00.000Z", "added": "2026-10-21T00:00:00.000Z", "brief": [ "In coffee, ochratoxin A (OTA) is made only by *Aspergillus* species of sections *Circumdati* and *Nigri*; *Penicillium* species are not involved.1,8", "OTA-producing fungi can grow between water activity 0.80 and 0.95; 5 days or less in that range on the drying yard prevented OTA accumulation in trials.1,2", "Rewetting of dried coffee may be more serious than slow drying, according to the FAO guidelines on mould prevention in coffee.2", "Reported OTA losses in roasting range from under 30% to almost 100%, depending on temperature, time and study.1,11,15", "The EU allows at most 3.0 µg/kg OTA in roasted coffee and 5.0 µg/kg in soluble coffee; green coffee has no maximum level.4" ], "quickFacts": [ { "label": "What it is", "value": "A chlorinated mould toxin; L-phenylalanine linked to a dihydroisocoumarin (EFSA)" }, { "label": "Producers in coffee", "value": "Aspergillus sections Circumdati (A. ochraceus, A. westerdijkiae, A. steynii) and Nigri (A. carbonarius, A. niger)" }, { "label": "Risk window in drying", "value": "Water activity 0.80–0.95 (Codex)" }, { "label": "No growth / no toxin", "value": "Below aw 0.76–0.78 / below aw 0.80 (Codex)" }, { "label": "EU maximum levels", "value": "Roasted coffee 3.0 µg/kg; soluble coffee 5.0 µg/kg; green coffee none" }, { "label": "Standard method", "value": "Immunoaffinity clean-up and HPLC (EN 14132 for roasted coffee)" } ], "aka": [ "OTA in coffee", "Ochratoxin A in coffee" ], "linkTerms": [ "ochratoxin", "ochratoxins", "2'R-ochratoxin A", "2′R-OTA", "14R-ochratoxin A" ], "related": [ "contaminants-and-food-safety", "moisture-and-water-activity", "microorganisms", "drying", "mechanical-dryers", "processing-defects", "green-coffee-storage", "hulling-and-dry-milling", "harvesting-and-sorting", "natural-process", "wet-hulled", "roasting-contaminants", "decaffeination", "coffee-berry-borer" ], "contested": [ "OTA loss during roasting: the Codex code gives 65–100% depending on the process1, as does a 2008 Italian study14; a 2001 study found 69% over all conditions and noted that seven of the nine studies then available reported 69–96%12; a 2010 kinetic study measured 8–98% across 12 temperature–time combinations11; a 2024 review gives 12–90%8; a 1994 Swiss study on spoiled beans judged a loss of less than 30% likely.15", "Roast degree and OTA loss: a 2010 kinetic study and a 2003 study found larger losses at higher temperatures or darker roasts11,13, while a 2001 study found no statistically significant differences between roasting times and colours.12", "OTA formation before harvest: the Codex code states that it is not certain whether OTA-producing fungi can produce OTA on the plant1; the FAO guidelines state that there is now good evidence that seed infection can take place in the orchard and produce OTA by harvest2; a 2003 Brazilian study found very low infection rates in cherries taken from trees.10", "OTA in the brew: a 2014 study found 22.3–66.1% of the OTA in ground coffee in seven kinds of beverage17; a 2008 study reported that a moka pot reduced OTA by 50–75% while Turkish coffee reduced it little14; EFSA notes that more OTA has been found in brewed coffee than in the roasted beans, and considers it likely that OTA bound to coffee polysaccharides is released during brewing.3" ], "corrections": [ { "date": "2026-10-21T00:00:00.000Z", "change": "EU maximum levels (3.0 µg/kg roasted, 5.0 µg/kg soluble, none for green coffee) confirmed in the official EUR-Lex consolidated text of Regulation (EU) 2023/915; source now points to the version read.", "reason": "The writer could not open the annex and had taken the values from another entry." }, { "date": "2026-10-21T00:00:00.000Z", "change": "The 2001 roasting study's comparison now reads 'seven of the nine studies then available' instead of 'seven of nine earlier studies' (text, contested, key studies, chart label).", "reason": "The abstract counts nine studies in total, not nine earlier ones." }, { "date": "2026-10-21T00:00:00.000Z", "change": "EFSA statements matched to the opinion's wording – genotoxicity mechanisms unclear; roasted coffee 'appears to be' the major source of 2′R-OTA; release of bound OTA in brewing given as likely, not established; binding described as a heat reaction, not as 'during roasting'.", "reason": "The paraphrases were stronger than EFSA's text." }, { "date": "2026-10-21T00:00:00.000Z", "change": "EU sampling for lots of 15 t or more now states that they are divided into sublots of 15–30 t, each giving 100 incremental samples and a 10 kg aggregate sample.", "reason": "Implementing Regulation (EU) 2023/2782, Annex I, Part G, Table 1." }, { "date": "2026-10-21T00:00:00.000Z", "change": "Penicillium producers named as P. verrucosum and P. nordicum; husk called a 'significant' (not 'major') OTA source; shipping measure reads 'no unprotected deck stowage'; 'whether OTA came from natural infection or inoculation' removed from the reasons roasting results differ; the 5-day drying figure also cited to the FAO guidelines.", "reason": "Matches the wording of the cited sources (Ostry et al. 2013; Viani 2002; Codex para. 47; Ferraz et al. 2010 and the 2024 review do not name contamination route; FAO guidelines state 5 days 'in this range')." } ], "sources": [ { "id": "s1", "title": "Code of Practice for the Prevention and Reduction of Ochratoxin A Contamination in Coffee (CAC/RCP 69-2009)", "authors": "Codex Alimentarius Commission (FAO/WHO)", "year": 2009, "publisher": "Codex Alimentarius", "url": "https://www.fao.org/input/download/standards/11250/CXP_069e.pdf", "tier": "A", "tierNote": "Full text read on 21 Oct 2026 in the copy of this PDF held by the project's quote checker (fetched from this URL on 20 Oct 2026); the URL itself could not be opened in this session.", "quote": "In coffee, only Aspergillus species, specifically A. ochraceus and related species (A. westerdijkiae and A. steynii), A. niger and related species, and A. carbonarius are involved.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s2", "title": "Guidelines for the Prevention of Mould Formation in Coffee", "authors": "FAO", "year": 2006, "publisher": "Food and Agriculture Organization of the United Nations", "url": "https://www.fao.org/fileadmin/user_upload/agns/pdf/coffee/guidelines_final_en.pdf", "tier": "A", "tierNote": "Full text read on 21 Oct 2026 in the copy of this PDF held by the project's quote checker (fetched from this URL on 20 Oct 2026); the URL itself could not be opened in this session.", "quote": "Rewetting may be more serious than slow drying.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s3", "title": "Risk assessment of ochratoxin A in food", "authors": "EFSA Panel on Contaminants in the Food Chain (CONTAM); Schrenk, D.; Bodin, L.; Chipman, J. K.; et al.", "year": 2020, "publisher": "EFSA Journal 18(5), 6113", "url": "https://doaj.org/article/dab537cc580d4816a8595f9f78786ac2", "doi": "10.2903/j.efsa.2020.6113", "tier": "A", "tierNote": "Full opinion read on 21 Oct 2026 in the Wageningen University eDepot copy (edepot.wur.nl/549437); the DOAJ record gives the abstract only.", "quote": "As a consequence, the TWI of 120 ng/kg bw as established by the CONTAM Panel in 2006 is no longer valid.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s4", "title": "Commission Regulation (EU) 2023/915 on maximum levels for certain contaminants in food (consolidated text, 01.01.2025), Annex I, section 1.2", "authors": "European Commission", "year": 2025, "publisher": "EUR-Lex", "url": "https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:02023R0915-20250101", "tier": "A", "tierNote": "Regulation; cited as specification. Annex I, entries 1.2.14 (3,0 µg/kg) and 1.2.15 (5,0 µg/kg) read in the official EUR-Lex consolidated HTML of 1 January 2025 on 21 Oct 2026 (verification); no ochratoxin A entry names green or unroasted coffee. The contaminants and food safety entry cites the consolidation of 1 July 2025 with the same values.", "quote": "Roasted coffee beans and ground roasted coffee except products listed in 1.2.15", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s5", "title": "Commission Regulation (EC) No 123/2005 of 26 January 2005 amending Regulation (EC) No 466/2001 as regards ochratoxin A", "authors": "European Commission", "year": 2005, "publisher": "Official Journal of the European Union (legislation.gov.uk copy, original as adopted)", "url": "https://legislation.gov.uk/eur/2005/123/data.pdf", "tier": "A", "tierNote": "Regulation; cited for the historical maximum levels and recitals it set, not as current law.", "quote": "Wine, coffee and beer were identified as significant contributors to the human OTA exposure.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s6", "title": "Commission Implementing Regulation (EU) 2023/2782 of 14 December 2023 laying down the methods of sampling and analysis for the control of the levels of mycotoxins in food and repealing Regulation (EC) No 401/2006", "authors": "European Commission", "year": 2023, "publisher": "EUR-Lex", "url": "https://eur-lex.europa.eu/eli/reg_impl/2023/2782", "tier": "A", "tierNote": "Regulation; cited as specification. Text read on 21 Oct 2026 in the LawPlayer copy (lawplayer.com/eu/act/32023R2782), as the EUR-Lex page returned metadata only. Annex I, Part G (coffee) and Annex II (performance criteria).", "quote": "The weight of the incremental sample shall be about 100 g, unless otherwise defined in this part G.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s7", "title": "EVS-EN 14132:2009 Foodstuffs – Determination of ochratoxin A in barley and roasted coffee – HPLC method with immunoaffinity column clean-up", "authors": "European Committee for Standardization (CEN)", "year": 2009, "publisher": "Estonian Centre for Standardisation and Accreditation (catalogue page)", "url": "https://www.evs.ee/en/evs-en-14132-2009", "tier": "A", "tierNote": "Standard; only the scope on the catalogue page was read, cited for what the standard specifies.", "quote": "This European Standard specifies a method for the determination of ochratoxin A content in barley and roasted coffee", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s8", "title": "Reduction in Ochratoxin A Occurrence in Coffee: From Good Practices to Biocontrol Agents", "authors": "López-Rodríguez, C.; Verheecke-Vaessen, C.; Strub, C.; Fontana, A.; Schorr-Galindo, S.; Medina, A.", "year": 2024, "publisher": "Journal of Fungi 10(8), 590", "url": "https://www.mdpi.com/2309-608X/10/8/590", "doi": "10.3390/jof10080590", "tier": "A", "tierNote": "Peer-reviewed narrative review; used for its overview statements, and its roasting range is reported as the review's own summary.", "quote": "The main OTA producers in coffee belong to Aspergillus sections Circumdati and Nigri.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s9", "title": "Producers and Important Dietary Sources of Ochratoxin A and Citrinin", "authors": "Ostry, V.; Malir, F.; Ruprich, J.", "year": 2013, "publisher": "Toxins 5(9), 1574–1586", "url": "https://www.mdpi.com/2072-6651/5/9/1574", "doi": "10.3390/toxins5091574", "tier": "A", "quote": "OTA is produced worldwide in foodstuffs by microfungi of the genera, Aspergillus, mainly in subtropical and tropical areas, and Penicillium, especially in temperate and colder zones", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s10", "title": "The source of ochratoxin A in Brazilian coffee and its formation in relation to processing methods", "authors": "Taniwaki, M. H.; Pitt, J. I.; Teixeira, A. A.; Iamanaka, B. T.", "year": 2003, "publisher": "International Journal of Food Microbiology 82, 173–179", "url": "https://foodsafetybrazil.org/?p=1638", "doi": "10.1016/S0168-1605(02)00310-0", "tier": "A", "tierNote": "Peer-reviewed paper; only the abstract was read, in a reproduction on Food Safety Brazil (re-read on 21 Oct 2026 in verification). The DOI resolves to the Elsevier article S0168160502003100 in this journal, but the publisher page did not render, so the abstract could not be compared there.", "quote": "Average infection rates for cherries taken from trees were very low", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s11", "title": "Kinetics of ochratoxin A destruction during coffee roasting", "authors": "Ferraz, M. B. M.; Farah, A.; Iamanaka, B. T.; Perrone, D.; Copetti, M. V.; Marques, V. X.; Vitali, A. A.; Taniwaki, M. H.", "year": 2010, "publisher": "Food Control 21, 872–877", "url": "https://ninho.inca.gov.br/jspui/bitstream/123456789/8940/1/Kinetics%20of%20ochratoxin%20A%20destruction%20during%20coffee%20roasting..pdf", "doi": "10.1016/j.foodcont.2009.12.001", "tier": "A", "tierNote": "Full text read in the INCA (Brazilian National Cancer Institute) repository copy. The paper's table of rate constants (0.10–0.43 min⁻¹) does not match the averages in its text (0.0687–0.3775 min⁻¹); the entry gives neither.", "quote": "Coffee treated with spouted bed roasting significantly reduced the OTA level from 8% to 98%.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s12", "title": "Effect of roasting conditions on reduction of ochratoxin A in coffee", "authors": "van der Stegen, G. H. D.; Essens, P. J. M.; van der Lijn, J.", "year": 2001, "publisher": "Journal of Agricultural and Food Chemistry 49(10), 4713–4715", "url": "https://pubmed.ncbi.nlm.nih.gov/11600012/", "doi": "10.1021/jf0105586", "tier": "A", "quote": "Seven out of these nine reported that the relevant range of OTA reductions was between 69 and 96%.", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s13", "title": "Influence of roasting levels on ochratoxin A content in coffee", "authors": "Romani, S.; Pinnavaia, G. G.; Dalla Rosa, M.", "year": 2003, "publisher": "Journal of Agricultural and Food Chemistry 51(17), 5168–5171", "url": "https://pubmed.ncbi.nlm.nih.gov/12903986/", "doi": "10.1021/jf030116p", "tier": "A", "quote": "showed reductions of >90% in the ochratoxin A content, in both high and low contaminated samples.", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s14", "title": "Influence of roasting and different brewing processes on the ochratoxin A content in coffee determined by high-performance liquid chromatography-fluorescence detection (HPLC-FLD)", "authors": "La Pera, L.; Avellone, G.; Lo Turco, V.; Di Bella, G.; Agozzino, P.; Dugo, G.", "year": 2008, "publisher": "Food Additives & Contaminants", "url": "https://agris.fao.org/search/fr/records/65e007af4c5aef494fe7a892", "doi": "10.1080/02652030802112627", "tier": "A", "tierNote": "Abstract read in the FAO AGRIS record.", "quote": "The results provided evidence that roasting led to a significant drop on OTA levels (65-100%).", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s15", "title": "Ochratoxin A and coffee", "authors": "Studer-Rohr, I.; Dietrich, D. R.; Schlatter, J.; Schlatter, C.", "year": 1994, "publisher": "Mitteilungen aus dem Gebiete der Lebensmitteluntersuchung und Hygiene 85, 719–727", "url": "https://kops.uni-konstanz.de/server/api/core/bitstreams/bc427590-cc4c-4d1e-bd1b-254358aa3467/content", "tier": "A", "tierNote": "Journal paper of the Swiss Society of Food and Environmental Chemistry, read as a scanned copy in the University of Konstanz repository. The quote is copied as the OCR text reads it ('reduetion', 'eontent', 'plaee' are OCR misreadings of 'reduction', 'content', 'place').", "quote": "lt is likely therefore that a reduetion of the OA eontent during roasting of less than 30% takes plaee.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s16", "title": "Occurrence of the Ochratoxin A Degradation Product 2′R-Ochratoxin A in Coffee and Other Food: An Update", "authors": "Sueck, F.; Hemp, V.; Specht, J.; Torres, O.; Cramer, B.; Humpf, H.-U.", "year": 2019, "publisher": "Toxins 11(6), 329", "url": "https://doaj.org/article/cd7212e9a0094460a2e7c3374b7a9d26", "doi": "10.3390/toxins11060329", "tier": "A", "tierNote": "Abstract read in the DOAJ record; the full text (PMC) was behind a captcha.", "quote": "At 210 °C and above, the formation of 25% 2′R-OTA is observed in less than one minute.", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s17", "title": "Transfer of Ochratoxin A into Tea and Coffee Beverages", "authors": "Malir, F.; Ostry, V.; Pfohl-Leszkowicz, A.; Toman, J.; Bazin, I.; Roubal, T.", "year": 2014, "publisher": "Toxins 6(12), 3438–3453", "url": "https://doaj.org/article/fd99493bed9a4b4491b869853d9b9885", "doi": "10.3390/toxins6123438", "tier": "A", "tierNote": "Abstract read in the DOAJ record; the per-method values in the full text were not read.", "quote": "Depending on the type of process used, OTA transfer into coffee ranged from 22.3% to 66.1%.", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s18", "title": "Effect of processing on ochratoxin A (OTA) content of coffee", "authors": "Viani, R.", "year": 2002, "publisher": "In: DeVries, J. W.; Trucksess, M. W.; Jackson, L. S. (eds), Mycotoxins and Food Safety, Advances in Experimental Medicine and Biology 504, Springer, 189–193", "url": "https://www.doi.org/10.1007/978-1-4615-0629-4_19", "doi": "10.1007/978-1-4615-0629-4_19", "tier": "B", "tierNote": "Book chapter by an industry scientist; abstract read on the publisher page. Used only beside Tier A sources and never for a number.", "quote": "cleaning and grading of green coffee are effective methods for reducing OTA levels in coffee", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" } ], "markdown": "## What ochratoxin A is\n\nOchratoxin A (OTA) is a toxin made by a few moulds. It is a by-product of their growth, not part of the coffee seed.1,2 The Codex code of practice for coffee calls it the primary food-safety issue in green coffee production.1\n\nOTA is a mycotoxin, a toxic substance made by a fungus.1 It forms only when the right mould meets the right water, food and temperature for long enough.1,2 The FAO guidelines call its causes essentially invisible. The moulds that cause smells and taints are not the ones that make OTA.2\n\nChemically, OTA is an amino acid, L-phenylalanine, joined to a ring structure that carries a chlorine atom.3 The ring part makes OTA strongly fluorescent. Laboratories use this to measure it.3,14\n\n
\n
\n
How the OTA molecule is built, and the form it partly turns into when heated. Schematic, not a chemical drawing.3,11,16
\n
\n\nThe European Food Safety Authority (EFSA) assessed OTA in 2020. It states that OTA causes kidney toxicity in several animal species and kidney tumours in rodents.3 The deep dive gives EFSA’s conclusions. This entry describes what authorities state; it gives no health advice.\n\n## Which moulds make it in coffee\n\nSeveral moulds of the genera *Aspergillus* and *Penicillium* can make OTA.1 In coffee, only *Aspergillus* species are involved.1,2\n\nThey fall into two groups, called sections. Section *Circumdati* holds *A. ochraceus* and its relatives *A. westerdijkiae* and *A. steynii*.1,8 Section *Nigri*, the black aspergilli, holds *A. carbonarius* and *A. niger*.1,8 Not every strain of these species produces the toxin.2,10\n\n*Penicillium* species make OTA mainly in temperate and colder zones. *Aspergillus* species make it mainly in tropical and subtropical areas, where coffee grows.9 The microorganisms entry describes the wider fungal community of coffee processing.\n\n## Where in the chain it forms\n\nOTA can form at several points between the tree and the roaster. Most fungal contamination happens after harvest, especially during drying.8,10\n\n- **On the ground.** Cherries left on the ground, especially in humid weather, can grow mould. The Codex code advises against collecting them; in wet climates only same-day collection is acceptable.1\n- **Waiting before processing.** Cherries held in bags or heaps heat up and ferment. This increases the OTA risk.1\n- **Slow drying.** Coffee passes through a range of moisture where OTA moulds can grow. The longer it stays there, the greater the risk.1\n- **Rewetting.** Dried coffee that takes up water again, from rain, condensation or damp floors, favours fast mould growth.1\n- **Storage and shipping.** Temperature changes in containers can make water condense on the coffee.1\n\nSome parts of the crop carry more OTA than others. Defective beans and husk – the dried fruit skin and pulp around natural coffee – sometimes hold more than sound beans.1,18 Sorting them out at the dry mill lowers the OTA in a lot, the batch traded as one unit.1,18\n\n
\n
\n
Where OTA risk arises from harvest to shipping, and the main measure the Codex code sets at each point. Schematic, not to scale; not a risk ranking.1,2
\n
\n\n## Drying and water activity\n\nWater activity (aw) describes how much water in a food is free for microbes to use. It runs from 0 (dry) to 1 (pure water). The moisture and water activity entry explains it.\n\nThe Codex code describes three bands for OTA moulds in coffee:1\n\n- **Above aw 0.95:** fast-growing moulds and yeasts grow first; OTA moulds are unlikely to grow.\n- **aw 0.80–0.95:** OTA moulds can grow. This is the danger zone of drying.\n- **Below aw 0.80:** they cannot make the toxin; below 0.76–0.78 they cannot grow.\n\nSo the key control is time. In trials, 5 days or less in the danger zone prevented OTA from building up.1,2 Thin layers, frequent turning and protection from rain shorten that time.1 The FAO guidelines add that rewetting may be more serious than slow drying.2\n\n## Roasting, brewing and the limits\n\nRoasting lowers OTA but does not reliably remove it. Reported losses range from under 30% to almost 100%.1,11,15 Higher temperatures and longer roasts destroyed more in a 2010 laboratory study.11 Part of the OTA changes into a closely related form during roasting.16\n\nBrewing moves part of the remaining OTA into the cup. In one 2014 study, 22.3–66.1% passed into the drink, depending on the method.17\n\nThe EU sets maximum levels of 3.0 µg/kg for roasted coffee and 5.0 µg/kg for soluble (instant) coffee.4 One µg/kg is one part per billion.2 Green coffee has no EU maximum level.4 The contaminants and food safety entry puts OTA beside the other hazards in coffee.\n\n\n\n## Chemistry and toxicology\n\n**Structure.** In EFSA’s description, the ochratoxins consist of L-phenylalanine linked by an amide bond to a substituted dihydroisocoumaric acid.3 OTA carries a chlorine substituent, which distinguishes it from ochratoxin B. Its formula is C20H18ClNO6 and its molar mass 403.8 g/mol.3 The isocoumarin part gives OTA a strong fluorescence, the basis of its detection.3 The FAO guidelines describe OTA as a heat-stable mould metabolite.2\n\n**Heat products.** Heating converts part of the OTA into 2′R-ochratoxin A (2′R-OTA), first reported as 14R-OTA. It is a diastereomer of OTA.3 In model experiments between 120 and 270 °C, isomerisation began at 120 °C. At 210 °C and above, 25% 2′R-OTA formed in less than one minute.16 EFSA states that roasted coffee appears to be the major source of 2′R-OTA.3 Its toxicity was not assessed in the sources opened for this entry.\n\n**Bound OTA.** EFSA cites evidence that OTA binds covalently to coffee polysaccharides, through esterification of its carboxyl group, as a further heat reaction.3 It considers it likely that some of these esters are split during brewing and release OTA into the brew, because higher amounts of OTA have been found in brewed coffee than in the roasted beans.3\n\n**EFSA’s 2020 assessment.** EFSA concluded that OTA is genotoxic in vitro and in vivo, but that the mechanisms are unclear; direct and indirect genotoxic and non-genotoxic modes of action might each contribute to tumour formation.3 As a consequence, it declared the tolerable weekly intake (TWI) of 120 ng/kg body weight it had set in 2006 no longer valid.3 It used a margin of exposure (MOE) approach instead, based on two reference points:3\n\n- Non-neoplastic effects: a benchmark dose lower confidence limit (BMDL10) of 4.73 µg/kg body weight per day, from kidney lesions in pigs. An MOE of 200 or more indicates low health concern.\n- Neoplastic effects: a BMDL10 of 14.5 µg/kg body weight per day, from kidney tumours in rats. MOEs were below 10,000 for almost all exposure scenarios.\n\nEFSA concluded that the tumour MOEs would indicate a possible health concern if genotoxicity is direct, and that the uncertainty is high.3 It named preserved meat, cheese, and grains and grain-based products as the most important contributors to chronic exposure; coffee is not named among them.3 The 2009 Codex code quotes the values current at the time: International Agency for Research on Cancer (IARC) Group 2B, possibly carcinogenic to humans, and a JECFA provisional tolerable weekly intake of 100 ng/kg body weight.1\n\n## The producing fungi in detail\n\nThe Codex code lists *A. ochraceus* and related species (*A. westerdijkiae*, *A. steynii*), *A. niger* and related species, and *A. carbonarius* as the OTA producers in coffee.1 A 2013 review places them in *Aspergillus* section *Circumdati* and section *Nigri*.9 A 2024 review names *A. westerdijkiae* and *A. steynii* as the strongest producers in section *Circumdati*, and *A. carbonarius* in section *Nigri*.8\n\nToxin production varies sharply between species. In a 2003 Brazilian study, *A. niger* was the most common of the three, but only 3% of its isolates produced OTA. Of the *A. ochraceus* isolates tested, 75% did, and 77% of *A. carbonarius* isolates.10 Finding black aspergilli on coffee is therefore not the same as finding an OTA risk.\n\n*Penicillium verrucosum* and *P. nordicum* make OTA mainly in temperate and colder zones.9 Both the Codex code and the FAO guidelines limit the coffee producers to *Aspergillus*.1,2 This matches the moisture and water activity and microorganisms entries.\n\n## Contamination along the chain\n\n**Before harvest.** The Codex code names two possible infection routes on the plant: through the flowers without visible signs, or by the coffee berry borer (*Hypothenemus hampei*) carrying spores into the fruit.1 It states that it is not certain whether OTA forms on the plant.1 The FAO guidelines see good evidence that it can.2 In the 2003 Brazilian study, infection rates of cherries taken from trees were very low; mean OTA rose from about 0.1 µg/kg at the tree stage to 3.3 µg/kg in storage.10 More mature, drier fruit and by-products such as husk and pulp can carry more spores of OTA producers.2\n\n**Ground and over-ripe fruit.** Fruit on the ground is more likely to be contaminated as contact time lengthens.1,2 If fallen fruit must be collected, the Codex code asks for separate storage and rapid processing and drying.1 Unripe and over-ripe cherries should be removed before processing.1\n\n**Delays and fermentation.** Holding harvested fruit in bags or heaps for up to a week causes high temperatures and quick fermentation, and raises the OTA risk.1 For washed coffee, the Codex code asks for fermentation as short as possible, 12 to 36 hours, and clean water.1 The harvesting and sorting and fermentation entries give the details.\n\n**Drying.** The Codex code divides drying into three stages.1 In the first, moisture falls slightly over 1–3 days for cherry and 1 day or less for parchment; aw stays above 0.95. The second stage has the fastest moisture loss and favourable conditions for OTA producers. In the third, the coffee is dry enough that they no longer grow.1 Rewetting can occur at any stage and favours rapid fungal growth.1\n\n**Storage and transport.** The Codex code states that coffee keeps drying below 60% relative humidity and starts to absorb water above 80%.1 Moisture can enter from damp floors and walls, leaks, wind-driven rain, dead air and mixing dry with wet coffee.1 In containers, temperature swings can condense the remaining water and rewet the coffee locally.1 The green coffee storage entry covers warehouse practice.\n\n**Defects and husk.** In lower-grade coffee, fruits with black and sour defects contained the highest OTA levels.1 Defects are not evenly distributed across the bean classes separated from bulk coffee, and defective beans and husk sometimes contain more OTA than sound beans.1 According to a 2002 review chapter, husk is a significant OTA source, and cleaning and grading green coffee are effective ways to reduce OTA.18\n\n## Water activity thresholds\n\nThe thresholds below come from the Codex code and the FAO guidelines; they are the same as in the moisture and water activity entry.1,2\n\n| Water activity (aw) | What OTA producers do | Source |\n|---|---|---|\n| Above 0.95 | Unlikely to grow; fast-growing hydrophilic fungi and yeasts grow first | Codex1 |\n| 0.80–0.95 | Can grow and produce OTA: the critical range during drying | Codex1 |\n| Below 0.80 | Can be present but produce no toxin | Codex1 |\n| Below 0.76–0.78 | Cannot grow | Codex1 |\n| 0.67–0.70 maximum, with moisture < 12.5% (wb) | Sufficient to protect parchment coffee from fungal damage | Codex1 |\n\nThe FAO guidelines relate these thresholds to moisture. In a data set of more than 2,000 samples, aw 0.76 corresponded on average to about 18% moisture in robusta cherry and about 16% in arabica parchment.2 At a 99% confidence level, the moisture figure fell to about 13% for both.2 The guidelines conclude that the recommended maxima of 12% (wb) for dry parchment and 13% (wb) for dry cherry include a substantial safety margin.2 The Codex code sets 12.5% for both.1\n\n## Codex measures by stage\n\nThe Codex code of practice CAC/RCP 69-2009 sets out good practice to prevent and reduce OTA.1 The main measures:\n\n| Stage | Measure | Source |\n|---|---|---|\n| Pre-harvest | Keep plants vigorous with good agricultural practice; no overhead irrigation during flowering; trap coffee berry borers; no uncomposted coffee waste in the plantation | Codex 111 |\n| Harvest | Do not collect fallen cherries, especially in humid conditions; in wet climates only same-day collection; store gleanings separately | Codex 141 |\n| Before processing | Process as soon as possible; dry cherries on the day of harvest where possible; remove unripe, over-ripe and diseased fruit | Codex 16, 17, 24, 251 |\n| Wet processing | Clean water; fermentation as short as possible, 12–36 h | Codex 291 |\n| Drying | Layers 3–5 cm (25–35 kg/m² of fresh parchment or cherry); turn constantly by day; ventilate at night; heap and cover after 1 day (parchment) or 3 days (cherry); avoid rewetting | Codex 381 |\n| Moisture check | Below 12.5% for parchment and cherry; meters calibrated against ISO 6673 | Codex 381 |\n| Storage | Bags on pallets, away from walls; damp-proof cement floor, waterproof roof, high ceiling for air circulation; no direct sun or heat sources; record initial condition | Codex 461 |\n| Dry mill | Low tolerance for black and sour defects; out-sorted defects not re-blended or sold to roasters unless a representative sampling plan and OTA analysis show them acceptable | Codex 43, 461 |\n| Shipping | Clean, dry, undamaged containers; moisture-absorbing cover (silica gel or cardboard) on bags; no unprotected deck stowage; moisture never above 12.5% | Codex 471 |\n\nThe Codex code cites the FAO guidelines of 2006, written so that producing countries could build their own national programmes.1 The guidelines name two tools: managing water availability from the start of drying, and favouring competing microorganisms and restrictive growth conditions before that point.2\n\n## Fate in roasting\n\nRoasting reduces measurable OTA, but studies disagree on how much. The values below are reported reductions; they are not comparable one to one, because samples, contamination levels and roasting equipment differ.\n\n
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OTA reduction by roasting as reported by eight sources. Ranges reflect different conditions within each source; the 1994 value is an upper estimate for spoiled beans.1,3,8,11,12,13,14,15
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\n\n**Kinetics.** A 2010 Brazilian study inoculated green arabica with *A. westerdijkiae* to 247 ng/g OTA. It roasted the beans in a spouted-bed roaster at 180–240 °C for 5, 8 or 12 min.11 Reductions ranged from 8.2% (180 °C, 5 min) to 98.9% (240 °C, 12 min). Loss followed first-order kinetics and the Arrhenius equation, with an apparent activation energy of 49.2 kJ/mol.11 Roast colour ranged from very light (Agtron 95) to very dark (Agtron 25).11\n\n
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OTA reduction after 5, 8 and 12 min of spouted-bed roasting at four temperatures, inoculated arabica (247 ng/g OTA in the green coffee). Measured points; lines only join them.11
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\n\n**Other studies.** A 2001 study roasted for 2.5–10 min, from light medium to dark. It found a 69% reduction over all conditions, with no significant differences between times or colours.12 It noted that nine studies on OTA reduction in roasting were then available, seven of which reported 69–96%.12 A 2003 Italian study found reductions above 90% in naturally contaminated samples roasted for espresso.13 A 2008 Italian study reported 65–100%, the same range the Codex code gives.1,14 EFSA summarises losses of 70% to more than 90% at temperatures above 180 °C.3 A 1994 Swiss study of spoiled beans found no significant reduction and judged a loss of less than 30% likely.15 A 2024 review gives 12–90%, depending on roasting temperature and initial contamination.8\n\n**Why results differ.** The sources point to several factors: roasting temperature and time, the roaster type and initial contamination.8,11,13 Part of the OTA can be converted to 2′R-OTA or bound to coffee polysaccharides rather than broken down.3,16 In 51 coffee samples from France, Germany and Guatemala, OTA was found in 96% and 2′R-OTA in 35%. The OTA to 2′R-OTA ratio ranged from 2.5:1 to 10:1, with a mean of 5.5:1.16 The highest values, 28.4 µg/kg OTA and 3.9 µg/kg 2′R-OTA, were in Guatemalan coffee.16\n\n## Decaffeination, soluble coffee and brewing\n\n**Decaffeination.** No source opened for this entry reported OTA changes during decaffeination. The decaffeination entry covers the processes.\n\n**Soluble coffee.** The EU sets a higher maximum level for soluble coffee (5.0 µg/kg) than for roasted coffee (3.0 µg/kg).4 No primary study on OTA through soluble coffee manufacture was opened for this entry.\n\n**Brewing.** A 2014 study prepared seven kinds of coffee beverage from ground roasted coffee naturally contaminated at 0.92 ng/g. Between 22.3% and 66.1% of the OTA passed into the drink, depending on the process.17 A 2008 study found a 50–75% reduction with a moka pot, but little reduction in Turkish coffee.14 EFSA notes that higher OTA levels have been observed in brewed coffee than in the roasted beans, and considers release of bound OTA during brewing a likely cause.3\n\n## Sampling and analysis\n\n**Uneven distribution.** OTA is concentrated in some beans, defects and husk, not spread evenly through a lot.1 The Codex code ties any re-use of out-sorted defects to a representative sampling plan and direct OTA analysis.1 The FAO guidelines ask for a spear sample from each sack, as a lot may be a blend of different sources.2\n\n**EU official sampling.** Implementing Regulation (EU) 2023/2782 sets the official sampling plan for coffee and coffee products in Annex I, Part G.6 An incremental sample weighs about 100 g. Lots of 15 t or more are divided into sublots of 15–30 t; each sublot gives 100 incremental samples, combined into a 10 kg aggregate sample. Smaller lots give 10–100 incremental samples and an aggregate sample of 1–10 kg.6 The laboratory sample is mixed thoroughly, with fine grinding if needed.6 A lot is rejected only if the result, minus the expanded measurement uncertainty, is above the maximum level.6\n\n**Standard method.** EN 14132 specifies immunoaffinity column clean-up and high-performance liquid chromatography (HPLC) for OTA in barley and roasted coffee.7 It is validated for roasted coffee from 0.2 to 5.5 µg/kg.7 An immunoaffinity column holds an antibody that binds OTA selectively, so other coffee compounds can be washed away.11 Detection uses OTA’s fluorescence (HPLC-FLD).3,11,14\n\n**A worked example.** The 2010 kinetic study extracted 25 g of coffee with methanol and 3% aqueous sodium bicarbonate (50:50). It cleaned the extract on an immunoaffinity column and measured at 333 nm excitation and 477 nm emission.11 Its limits of detection and quantification were 0.1 and 0.3 ng/g; recoveries were 78–86.5%.11\n\n**Performance criteria.** For OTA in most foods, the EU requires a limit of quantification of at most half the maximum level, preferably at most one fifth.6 For roasted coffee this means at most 1.5 µg/kg, preferably 0.6 µg/kg (our calculation from the 3.0 µg/kg level).4,6 Mean recovery should lie between 70 and 120%; repeatability RSDr at most 20% and reproducibility RSDR preferably at most 25%.6\n\n**Typical levels.** The FAO guidelines state that most commercial samples contain no detectable OTA at a detection limit of 0.1–0.5 µg/kg. Most positive samples fall below 5 µg/kg, and anything above 20 µg/kg is considered exceptionally high.2\n\n## Legal limits\n\n**EU.** Regulation (EU) 2023/915 sets maximum levels of 3.0 µg/kg for roasted coffee beans and ground roasted coffee (entry 1.2.14) and 5.0 µg/kg for soluble coffee (entry 1.2.15).4 No entry names green coffee.4 The first EU levels for coffee, in 2005, were 5.0 µg/kg for roasted and 10.0 µg/kg for soluble coffee.5 That regulation identified coffee, wine and beer as significant contributors to OTA exposure. It left a level for green coffee to be considered after further EFSA assessment.5\n\n**Codex.** The Codex code of practice sets no maximum level; it describes practices.1 A 2024 review states that neither Codex nor the US Food and Drug Administration has set an OTA limit for coffee.8\n\n**Switzerland.** The Swiss values were not opened for this entry; the contaminants and food safety entry gives them.\n\n## Reference values\n\nµg/kg equals ng/g and parts per billion (by mass).\n\n| Parameter | Value | Source |\n|---|---|---|\n| Molecular formula; molar mass | C20H18ClNO6; 403.8 g/mol | EFSA 20203 |\n| EU maximum level, roasted coffee beans and ground roasted coffee | 3.0 µg/kg | Reg. (EU) 2023/915, 1.2.144 |\n| EU maximum level, soluble coffee | 5.0 µg/kg | Reg. (EU) 2023/915, 1.2.154 |\n| EU maximum level, green coffee | None set | Reg. (EU) 2023/9154 |\n| Earlier EU levels (2005), roasted / soluble | 5.0 / 10.0 µg/kg | Reg. (EC) 123/20055 |\n| Water activity range for growth of OTA producers on the drying yard | 0.80–0.95 | Codex1 |\n| Time in that range that prevented OTA accumulation in trials | ≤5 days | Codex1, FAO2 |\n| Maximum moisture in drying, storage and shipping | 12.5% (wb), parchment and cherry | Codex1 |\n| Recommended maximum moisture (FAO guidelines) | 12% (wb) dry parchment; 13% (wb) dry cherry | FAO2 |\n| Storage relative humidity | Coffee dries below 60%; absorbs water above 80% | Codex1 |\n| Drying layer | 3–5 cm (25–35 kg/m²) | Codex1 |\n| OTA reduction by roasting | 65–100% depending on the process (Codex); 8–98.9% across 12 conditions (2010); <30% likely (1994) | Codex1, Ferraz et al.11, Studer-Rohr et al.15 |\n| Isomerisation to 2′R-OTA | Starts at 120 °C; 25% within 1 min at ≥210 °C (model experiments) | Sueck et al.16 |\n| OTA transfer into the beverage | 22.3–66.1% across seven preparations | Malir et al.17 |\n| EFSA BMDL10, non-neoplastic (pig kidney) / neoplastic (rat kidney tumours) | 4.73 / 14.5 µg/kg bw per day | EFSA 20203 |\n| EN 14132 validated range, roasted coffee | 0.2–5.5 µg/kg | EN 141327 |\n| EU sampling, lots ≥15 t | Sublots of 15–30 t; per sublot 100 incremental samples of ≈100 g, 10 kg aggregate | Reg. (EU) 2023/27826 |\n| EU method criteria for OTA | LOQ ≤0.5 × ML (preferably ≤0.2 × ML); recovery 70–120%; RSDr ≤20% | Reg. (EU) 2023/27826 |\n\n## Open questions\n\n- **Infection on the plant.** Whether OTA producers infect and produce OTA before harvest, and how important that route is, is not settled (see Contested).\n- **Toxicity of 2′R-OTA and bound OTA.** The sources opened here describe how they form, not how toxic they are; whether they should count towards limits was not addressed.\n- **Decaffeination and soluble coffee.** No primary study on OTA through these processes was opened for this entry.\n- **Coffee’s share of exposure.** EFSA’s 2020 summary does not name coffee among the main contributors; no coffee-specific exposure figure was found in the sources opened.\n\n## Key studies\n\n
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Ferraz et al., 2010 – Kinetics of OTA destruction in roasting. Roasted inoculated arabica at four temperatures and three times in a spouted-bed roaster and measured OTA by immunoaffinity clean-up and HPLC with fluorescence detection. Losses rose with temperature and time, from 8% to 98.9%, and followed first-order kinetics.

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Food Control 21, 872–877 · doi:10.1016/j.foodcont.2009.12.001

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van der Stegen et al., 2001 – Roasting conditions and OTA. Roasted coffee across times and colours from light medium to dark and found a 69% reduction overall, without significant differences between conditions. Of the nine studies then available on OTA and roasting, it noted that seven reported 69–96%.

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Journal of Agricultural and Food Chemistry 49(10), 4713–4715 · doi:10.1021/jf0105586

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Taniwaki et al., 2003 – Where OTA arises in Brazilian coffee. Measured OTA in 135 samples from five stages, from the tree to storage, and tested the OTA-producing species. Infection on the tree was low and rose after harvest, and toxin-producing ability differed sharply between A. niger, A. ochraceus and A. carbonarius.

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International Journal of Food Microbiology 82, 173–179 · doi:10.1016/S0168-1605(02)00310-0

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Sueck et al., 2019 – 2′R-OTA in coffee. Showed in model experiments that OTA isomerises from 120 °C and quickly above 210 °C, and measured both forms in 51 coffee samples. 2′R-OTA was found in about a third of them, at roughly one fifth of the OTA level on average.

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Toxins 11(6), 329 · doi:10.3390/toxins11060329

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Malir et al., 2014 – OTA from ground coffee to cup. Prepared seven kinds of coffee beverage from naturally contaminated ground coffee. Between about a fifth and two thirds of the OTA reached the drink, depending on the preparation.

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Toxins 6(12), 3438–3453 · doi:10.3390/toxins6123438

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\n\n*General information, not medical advice.*" }