Frequently Asked Questions

1. What is ochratoxin A (OTA) and what does it do?
2. What are the current regulatory limits for ochratoxin A (OTA) in coffee?
3. Why has the EU imposed a limit on ochratoxin A (OTA) in roasted and soluble coffee?
4. What is water activity, and why is it important?
5. Does mouldy-smelling coffee contain ochratoxin A (OTA)?
6. What are the most important things I can do to reduce the likelihood of ochratoxin A (OTA) in my coffee?
7. Where can I find training material to design courses and material to help coffee producers reduce the chance of ochratoxin A (OTA) contaminating their coffee?
8. How important is coffee in the overall ochratoxin A (OTA) consumption pattern of human beings?
9. How do regulatory limits for roasted, ground and soluble coffee relate to the raw product, i.e. green coffee?

1. What is ochratoxin A (OTA) and what does it do?

OTA is a mycotoxin – a secondary fungal metabolite produced by a few species of fungi in the genera Aspergillus and Penicillium. The Penicillium species have not been reported in coffee. The molecule is small and fairly water soluble and is a combination of an amino acid (phenylalanine) and a ten carbon polyketide (from fat metabolism). It contains a chlorine atom and this required for its biological activity. It is heat stable and easily extracted from ground coffee with hot water.

OTA has long been known as a potent nephrotoxin, a teratogen, and carcinogen. It has been implicated in the aetiology of Balkan Endemic Nephropathy, a lethal kidney disease of humans common in, but restricted to, several valleys in the Balkans. In the last ten years some work has indicated that its mode of carcinogenicity is ‘genotoxic’. However, OTA’s genotoxicity is not certain, and recent work funded by DG XII of the EU has demonstrated that DNA binding of OTA is not detectable with sensitive analytical methods, and is unlikely to represent a mechanism for OTA-induced tumour formation (Mally, A., et al., 2004).

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2. What are the current regulatory limits for ochratoxin A (OTA) in coffee?

In September 2004, as part of the process of harmonisation of food safety regulations across the EU Draft Commission Regulation amending Commission Regulation (EC) No. 466/2001 was notified to the World Trade Organization. This Regulation proposed maximum levels for OTA in roasted and ground coffee of 5.0 µg/kg, and in soluble coffee of 10 µg/kg.

The subsequent Commission Regulation (EC) No. 123/2005 setting maximum limits for Ochratoxin A, and amending Regulation (EC) No 466/2001 was adopted. This Regulation was published in the Official Journal of the European Union on 28 January 2005 and came into force on 1 April 2005. In the case of roasted coffee the maximum limit set was 5 ppb and in the case of soluble coffeeit was 10 ppb.

Within this Regulation, it also stated that the Commission would, based on an up-to-date risk assessment on OTA to be performed by the European Food Standards Authority (EFSA), take into account prevention measures applied to reduce OTA, and consider setting a maximum level for OTA in green coffee no later than June 30^th 2006.

The latest European Commission Regulation (EC) No. 1881/2006 of 19 December 2006, as a result of this process, and which entered into force on 1 March 2007, did not set limits on green coffee, and made no changes to the maximum limits for OTA in roasted coffee and soluble coffee of 5 ppb and 10 ppb respectively. However, green coffee does remain under review and there is provision for annual reporting on OTA occurrence and prevention measures. A PDF copy of the full Regulation text can be downloaded here.

Historically, and prior to the 2006 Commission Regulation (EC) No. 1881/2006, within Europe a number of individual governments set maximum levels for OTA in roasted, soluble, and, in some cases, green coffee. These are detailed in the table below. It should be noted that each EU member state retains the right to adopt national legislation for the protection of human health where no EC standard exists, and to maintain that national legislation even if an EC standard is adopted by justifying necessity for the protection of human health due to, for example, particular national consumption patterns:

	Green	Roasted	Instant
Czech Republic	10	10	10
Finland	5	5	5
Germany	-	3	6
Greece	20	-	-
Hungary	15	10	10
Italy	8	4	4
Netherlands	-	10	10
Portugal	8	4	4
Spain	8	4	4
Switzerland	5	5	5

Existing national limits for OTA in coffee in Europe (ppb)

Note: the status of these limits differ. Some are embodied in law or implementing legislation, others are customs instructions or guidelines for food safety inspectors.
Note: correct as of November 2004.

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3. Why has the EU imposed a limit on ochratoxin A (OTA) in roasted and soluble coffee?

Historically, the EU has put limits on the permissible maximum limits of OTA in several commodities in order to minimize exposure of the public to what might be a genotoxic renal carcinogen. In the early 1990s EU authorities initiated a programme for the harmonization of regulations relating to mycotoxins in foodstuffs – including maximum limits for OTA in foodstuffs such as coffee. In the case of staple commodities such as grain, a limit reduces the average exposure of the public to the toxin. With foodstuffs such as coffee, where few people consume enough to affect their average exposure, the rationale is to protect the public from any instances of high exposure.

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4. What is water activity, and why is it important?

Water activity (A_w) is a measure of water availability. It combines the amount of water with how closely it is held in the liquid/crystalline phase. Moisture content (m.c.) is strictly a measure of the amount of water. However, water is bound differently to different commodities, so the same proportion of water in two types of seed can correspond to different degrees of water availability. We want to know this because the growth of micro organisms (as well as mites and insects) is predicted by A_w, and not by m.c.

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5. Does mouldy-smelling coffee contain ochratoxin A (OTA)?

The fungi that produce OTA in coffee do not produce the volatile compounds that produce a mouldy or earthy smell. However, if coffee has this smell, it is likely that it has been damp for some time and these conditions would also encourage the growth of OTA-producing fungi. On this basis, if OTA-producers are present in mouldy smelling coffee, it is very likely there is also OTA.

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6. What are the most important things I can do to reduce the likelihood of ochratoxin A (OTA) in my coffee?

Coffee sometimes contains OTA at harvest but the most important periods for the development of OTA, in problematic quantities, occur when water is re-introduced to the partly dried product.

This can occur as coffee dries for the first time, for example after 3 to 5 days of sun drying. This can also occur at a later stage by storing coffee that has not been fully or evenly dried, or by storing coffee (especially poorly dried coffee) in conditions where condensation may take place.

Coffee farmers should have a plan to avoid re-wetting during drying, and be doubly sure of their method for deciding when coffee is fully dried. They should also make sure all storage areas are dry and well ventilated.

Coffee traders need to ensure that they can accurately assess coffee moisture and should not rely on single determinations. Only well dried coffees should be mixed, and do not store coffee that is not fully dried (i.e. 13% db = 11.5% wb). Finally, all stores should be dry and well ventilated.

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7. Where can I find training material to design courses and material to help coffee producers reduce the chance of ochratoxin A (OTA) contaminating their coffee?

The global project, ‘Enhancement of coffee quality through the prevention of mould formation’, has developed a comprehensive training resource to assist extensionists, and other trainers, in developing training packages suited to their needs. The resource, which addresses Good Hygiene Practices along the coffee chain is available for download from this website, and is available in English, French and Spanish. Please click here for more information and to go to the training resource.

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8. How important is coffee in the overall ochratoxin A (OTA) consumption pattern of human beings?

Risk assessments have been carried out by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), as well as in Canada and Scandinavia. Both JECFA, and the more recent 2002 SCOOP study on the 'Assessment of dietary intake of ochratoxin A by the population of EU member states', indicate that coffee is a relatively minor contributor to the overall OTA intake in Europe.

Cereals are the main contributors (50%) followed by wine (13%), coffee (10%), spices (8%), others (6%), beer (5%), cocoa (4%), dried fruits (3%) and meat (1%). Fruit juice provides the main contribution from the category 'Others':

Taken from report of experts participating in Task 3.2.7: Assessment of dietary intake of Ochratoxin A by the population of EU member states, January 2002, Figure 18, p.152.

At its 56^th meeting in 2001, JECFA calculated the mean OTA intake to be 45 µg/kg bw/week, below its Provisional Tolerable Weekly Intake level of 100 µg/kg body weight/week. The Scientific Committee for Food (SCF) Working group on Contaminants suggested a Tolerable Daily Intake of 5 µg/kg bw/day in 1998. Exposure as identified in the SCOOP study therefore appears to be below the values indicated by both the SCF and JECFA.

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9. How do regulatory limits for roasted, ground and soluble coffee relate to the raw product, i.e. green coffee?

No EU limits have yet been set for green coffee. European Commission Regulation (EC) No. 1881/2006 of 19 December 2006, which entered into force on 1 March 2007, did not set limits on green coffee. However, green coffee remains under review and there is provision for annual reporting on OTA occurrence and prevention measures. A PDF copy of the full Regulation text can be downloaded here.

It is important to note that processing of green coffee (roasting, soluble coffee manufacturing or decaffeination) removes a significant percentage of OTA. There are a number of studies on the effect of roasting on OTA contamination, and of those that apply conditions reflecting standard roasting practices, a substantial reduction of OTA during roasting occurs. For green coffees with relevant OTA contamination the reduction ranged from 69% to 96%.

Other studies have shown that standard decaffeination processes remove about 75% of the OTA present before decaffeination. This is plausible, as OTA is quite soluble in the extraction media normally used in decaffeination.

Therefore, by applying a conservative reduction of OTA during processing of 66%, the European Coffee Federation suggests in its green coffee buying guidelines that green coffee with an OTA contamination of 15 ppb will result in a finished product (be it roasted or soluble) that does not exceed the EU maximum limits.

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