- Email: [email protected]
Enhancement of coffee quality by mould prevention
Food Control 14 (2003) 245–249 www.elsevier.com/locate/foodcont
Enhancement of coffee quality by mould prevention Gerrit H.D. van der Stegen
*
SaraLee/DE N.V, P.O. Box 2, 3500 CA Utrecht, Netherlands Received 11 November 2001; received in revised form 16 September 2002; accepted 17 September 2002
1. Introduction A description of the coffee production chain is presented together with an overview of the gathered relevant basic data. Based upon evaluation thereof the European coffee sector chose for a strategy of prevention to deal with the occurrence of mould growth. The project, which was developed under international co-operation, the ICO/FAO Mould Prevention Project, is described. Finally the overall results so far are presented.
The world production of coffee amounts to 110 million bags/year (60 kg bags, 6.6 million tons/year). About 90 million bags/year are exported and about half of them come to the EU. Maritime transport goes these days almost completely in sea-containers, either in bulk (21 ton/container) or in bags (18 ton/container). Per year around 1/4 million containers with coffee are arriving in the EU.
2. Description of coffee production chain Coffee is grown in over 50 countries around the world, all in the tropical region. Almost all of them are developing countries. Internationally traded coffee is produced almost completely from two different botanical species. About 2/3 of the coffee stems from Coffea arabica, mainly grown in Central and South America and in East Africa (the origin of this coffee). Another 1/3 comes from Coffea canephora robusta, mainly grown in Africa and Asia. Some countries export substantial amounts of both types, e.g. Brazil, Ecuador and India (Coffee Statistics 1999). Worldwide 3/4 of all coffee is produced by small farmers. In total an estimated 250 million people are dependent on coffee production in these countries. After harvesting mainly two different types of primary processing are used. These processes differ in the way the beans are separated out of the coffee berry. For arabicaÕs in areas where water is abundant mainly the so-called wet processing is practised. In areas with shortage in water and almost all robustaÕs are processed via the so-called natural or dry process. The wet process requires higher investments, is more labour intensive and generally brings a higher price.
*
Tel.: +31-30-297-91-11.
The export of coffee generates for the producing countries annual foreign exchange earnings of around 10 billion €/year. This makes coffee value-wise, after oil, the second largest export product from developing countries. Many producing countries depend heavily on coffee, some for up to 3/4 of their export earnings (Coffee Statistics 1999). Further processing of the coffee, like decaffeination and instant production, is done both in the producing countries and in the consuming countries. Production of roast (and ground) coffee is for reasons of freshness mostly done in/near to the country of consumption. The main countries of coffee consumption are by total volume USA, Germany, Japan and France and by per capita consumption the Scandinavian countries, Austria and the Netherlands. Regular R&G coffee covers about 3/4 of the European coffee consumption and instant coffee about 1/5.
0956-7135/03/$ - see front matter 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0956-7135(03)00009-4
246
G.H.D. van der Stegen / Food Control 14 (2003) 245–249
3. Occurrence of OTA and its fate in processing Mould growth can occur on a wide range of agricultural products, like cereals, grapes, and green coffee beans. For coffee the risk of mould growth exists at inappropriate drying of the green coffee beans/berries and at rewetting of the green coffee beans, e.g. due to condensation. Aspergillus ochraceus is capable of growing and producing of ochratoxin A (OTA) on partially dried/rewetted green coffee (Bucheli, Kanchanomai, Meyer, & Pittet, 2000; Frank, 1997, 1999a, 1999b; Viani, 2002). Till the last decade of the 20th century the general understanding was that OTA is degraded during coffee roasting. Occurrence of OTA in Japanese retail coffee samples was reported (Tsubouchi, Terada, Yamamoto, & Sakabe, 1988), the coffee sector then initiated a number of studies. Among these are several studies about the fate of OTA during processing of the coffee in the consuming countries (Blanc, Pittet, Munoz-Box, & Viani, 1998; Heilmann, Rehfeldt, & Rotzoll, 1999; van der Stegen, Essens, & van der Lijn, 2001), a survey on coffee final products on European markets (van der Stegen et al., 1997) and a fact finding pilot study (Frank, 1997, 1999a, 1999b). In the framework of the latter, expert mycologists from University of Surrey/UK and Tech. University of Denmark made field trips to producing countries, covering major coffee types and major primary processing methods. For decaffeination it was shown that 3/4 of the OTA present is removed by the extraction (Heilmann et al., 1999). In total nine studies about reduction during roasting are now published. Seven of them showed high percentages of OTA reduction up to 96% respectively almost complete. Two studies had deviating results showing almost no reduction, however these studies applied heating of the coffee beans clearly outside the range of normal coffee roasting. From the series of publications it can be concluded that the OTA is reduced by 3/4 during roasting, partly by physical removal with the chaff partly by not yet fully elucidated mechanisms (Micco, Grossi, Miraglia, & Brera, 1989; van der Stegen et al., 2001; Wilkens & Joerissen, 1999). The remainder of the OTA is mainly extracted with water (Blanc et al., 1998; van der Stegen et al., 1997). Studies on sorting of coffee to remove contaminated beans are still ongoing. Results obtained so far are not yet conclusive. Also a number of transport trials, registering temperature and humidity fluctuations in the container during transport have been done. The obtained results show high fluctuations during over-land transport, with risk for condensation particularly in the port of arrival. Such risk seems understandable considering that these containers are stuffed in the tropics and being transported and unloaded in the colder climates.
Since 1995 in total 985 results on regular R&G and 359 results about instant coffee (regular + decaf) have been published (Bresch, Urbanek, & Hell, 2000; Burdaspal & Legarda, 1998; Consumerorganisations, various years; Jorgensen, 1998; Koch, Steinmeyer, Tiebach, Weber, & Weyerstahl, 1996; Maierhofer, Dietrich, & Maertlbauer, 1995; National results from EU survey, 1999; Patel, Hazel, Winterton, & Gleadle, 1997; van der Stegen et al., 1997). The frequency distribution of all these results is given in the figure below, showing that 71% of the instants and 83% of the regular R&G samples fall in the category ‘‘<1 ppb’’.
4. Human exposure and effects of a regulatory limit In its February 2001 evaluation JECFA (JECFA, 2001, 56th meeting), estimated the mean total dietary intake of OTA to be 45 ng/kg b.w./week. Using for coffee a weighted mean of 0.86 ppb and a consumption of 170 g R&G/week (which is equals the high per capita consumption in Scandinavia, acc. Coffee Statistics 1999) it estimated coffeeÕs share in the total intake to be 4–7%. JECFA retained the previously established PTWI of 100 ng/kg body weight per week, pending results of ongoing studies. It recommended a further review of OTA in 2004. By consistently using a Ôweekly intakeÕ, JECFA signals that its concern with respect to OTA is its chronic toxicity. In its summary and conclusions document JECFA states that ‘‘no cases of acute intoxication in humans have been reported’’. From JECFAÕs concern about chronic toxicity it can be derived that particularly mean levels of intake should get focus. An incidental high level in a product, of course, contributes to the mean, but as the concern is not about acute toxicity, the focus should be more on the mean levels for the total population respectively the heavy users. A maximum limit for OTA in coffee can have a number of effects: • eliminating coffees with values above the limit from supply to the consumer; • changing the distribution curve below the limit value, with an actual drift up to the limit; • effecting the export earnings from producing countries. The effect of eliminating high values both on mean value of the remaining samples and on economies of producing countries can be estimated from the available data (will be shown below). The effect of the distribution curve drifting upwards to the limit is more difficult to estimate. With the curve now being very skewed to the
G.H.D. van der Stegen / Food Control 14 (2003) 245–249
lower end, it might easily raise the mean level of the remaining samples. It is important to be aware of such possibility. From the data sets for regular R&G and instant coffees, as shown in Fig. 1, the reduction of the mean OTA level by removal of the high values can be calculated and is shown in Fig. 2 (without taking into account any drift up to the limit). Coffee provides an estimated 4–7% of average human intake. Even if a regulatory limit were imposed removing 3% of coffee containing the highest amount of OTA, thus reducing the mean level reaching the consumer in coffee by 25–30% this actually will only result in a reduction in total mean human exposure of less than 2%. For the coffee growing countries, rejecting 3% from the coffee would induce for them a loss of export volume valued at 300 million €/year and will hit some producing countries very seriously, particularly those depending most strongly on coffee. At world wide 3% rejection, the most severely hit country will loose 1/4 of its total export earnings and six more countries will loose between 5% and 10% of their total export earnings (not just coffee). These arguments brought the coffee sector to set their strategy for prevention of mould growth instead of a regulatory limit.
Fig. 1. Distribution of published data on coffee samples over OTA levels (1995–2001).
247
5. ICO/FAO mould prevention project In a fact finding pilot study, commissioned by the European coffee sector, expert mycologists from University of Surrey/UK and Tech. University of Denmark made in 1996–1998 field trips to producing countries, covering major coffee types and major primary processing methods. First guidelines for preventing mould growth were drafted during an international coffee conference 1997 in Nairobi (Proceedings ASIC, 1997). Since then a project for enhancement of coffee quality through prevention of mould formation was developed to cover all coffee producing countries. The International Coffee Organisation (ICO/London, an intergovernmental body) took the role of supervisory body and FAO/Rome the role of project executing agency. The project is budgeted with US$5.6 million and runs from 1999 to 2004. Main funders are the Common Fund for Commodities, the Dutch government and the European coffee sector. The project uses a two step approach. In the Ôfirst waveÕ a number of Ôlead countriesÕ build up local expertise, local HACCP-like models, develop training material and start with the training. The first country to start was Uganda (1999). India, Kenya, Indonesia, Brazil, Colombia and recently also Cote dÕIvoire are the other Ôlead countriesÕ. In a Ôsecond waveÕ of Ôsurrounding countriesÕ dissemination through training and implementation of GAP/GMP will be done. Ecuador, Ethiopia, Nicaragua and Vietnam are likely to enter soon into this step (Viani, 2002). Several producing countries have also developed substantial own activities on mould prevention in parallel to the formal ICO/FAO prevention project. All activities geared to the common goal will help. After the first meeting during the 1997 Nairobi coffee conference, further mould prevention Workshops took place in Helsinki 1999 and Trieste 2001 (Proceedings ASIC, 1999, 2001). Recently updated guidelines for ‘‘DoÕs and DonÕts’’ in mould prevention have been issued under the joint headings of ICO/London, FAO/ Rome and the European OTA Taskforce (Proceedings ASIC, 2001).
6. Evaluation of status so far
Fig. 2. Reduction of mean OTA level by removal of high values (without drift up to limit).
To evaluate any developments in the mean OTA levels of coffee sold on the European market all data from random/representative sampling published in scientific journals or published by consumer organisations or available from the 1999 EU national Food Inspections screening are fed into a data base (Bresch et al., 2000; Burdaspal & Legarda, 1998; Consumerorganisations, various years; Jorgensen, 1998; Koch et al., 1996; Maierhofer et al., 1995; National results from EU
248
G.H.D. van der Stegen / Food Control 14 (2003) 245–249
Table 1 Mean OTA levels in regular R&G coffees over the recent years (in ppb, with number of samples between brackets) Year of sampling
Germany
France
EU-memberstates (all together)
Mean concentration in beverage (lg/litre)a
1995 1996–2000
0.7 (140) 0.5 (220)
0.6 (40) 0.3 (62)b
0.8 (492) 0.5 (492)b
0.03 0.02
a
At 40 g of coffee/litre of water as a usual brewing strength. Among the French data there is uncertainty about two samples with identical code, but one labelled ‘‘ground’’, reported to have quite different results. In above table the result for the ground sample is taken, as the difference likely relates to mycotoxin inhomogeneity. b
survey, 1999; Patel et al., 1997; van der Stegen et al., 1997). The collected data allow for regular R&G coffee the evaluation as given in Table 1, showing a substantial decrease in mean OTA levels over the recent years. From the total 359 available data on instant coffee a similar time trend evaluation cannot be made, as the data are very much clustered. Nearly half of these data, 167 samples, originate from one country-year combination (UK 1995). The mean OTA level over all 359 samples of instant coffee amounts 1.4 ppb. Another complication with instant coffees can be the occurrence of adulteration with non-coffee-bean materials. Coffee beans themselves contain hardly any xylose (<0.3%). There are indications that OTA levels in products sold as instant coffee are correlated with elevated xylose levels, which would turn the issue from a contaminated coffee beans issue into a fraudulent raw materials issue (Pittet, Tornare, Huggett, & Viani, 1996). The question at the end of course is what does this all mean in the cup as consumed? From the data in Table 1 and the overall mean in instant coffees can be derived that the mean OTA level in brewed regular coffee (around 40 g coffee/litre) reduced in the period Õ95 to Õ01 from 0.03 to 0.02 lg/ litre and that the mean level for coffee prepared from instant (around 14 g/litre) amounts also to 0.02 lg/ litre, which is low compared to other concerned drinks (Otteneder & Majerus, 2001).
7. Summary Coffee is grown in over 50 countries around the world. Almost all of them are developing countries. The export of coffee generates for these countries annual foreign exchange earnings of around 10 million €/year. Mould growth can occur on several agricultural products, like cereals, grapes, and green coffee beans. For coffee the risk of mould growth exists at inappropriate drying of the green coffee beans/berries and at rewetting of the green coffee beans. A. ochraceus is capable of growing and producing of OTA on partially dried/rewetted green coffee. During decaffeination of green coffee and also at roasting of green coffee 3/4 of the OTA is removed.
Published data about occurrence of OTA in instants and regular R&G coffees show a distribution very much skewed to the lower levels resp. below detection limit. Percentages of 70–85% of the samples are in the category ‘‘<1 ppb’’. JECFA estimated, in its February 2001 evaluation, that the mean total dietary intake of OTA was 45 ng/kg b.w./week and that the coffeeÕs share in the total intake was 4–7%. It used for coffee a weighted mean of 0.86 ppb. Applying the instrument of maximum limits on coffee will induce some lowering of mean level plus economic damage in producer countries, in some countries very seriously. A possible reduction of 25–30% in the mean OTA level is estimated from the current distribution curves. A change in the skewedness of the distribution, e.g. by a drift up to the limit, can easily outbalance this effect. The effect on total exposure would anyhow be very small (<2%), as coffee is only a minor contributor in OTA. These arguments brought the coffee sector to set their strategy for prevention of mould growth instead of a regulatory limit. With the help of international organisations, FAO/ Rome, ICO/London and CFC/Amsterdam, a worldwide mould prevention project was initiated which runs from 1999 to 2004. In parallel communication channels in the coffee sector have been used to raise awareness for the issue in the whole coffee world. Occurrence data collected in recent years already show a substantial decrease in the mean OTA level for R&G coffee, at least as big as what could be achieved by regulatory limits. In the beverage as consumed the mean level has gone down from 0.03 to 0.02 lg/litre, which is a low level compared to some other concerned drinks.
References Blanc, M., Pittet, A., Munoz-Box, R., & Viani, R. (1998). Behavior of ochratoxin A during green coffee roasting and soluble coffee manufacture. Journal of Agricultural and Food Chemistry, 46, 673–675. Bresch, H., Urbanek, M., & Hell, K. (2000). Ochratoxin A in coffee, tea and beer. Archiv fur Lebensmittelhygiene, 51, 81–128. Bucheli, P., Kanchanomai, C., Meyer, I., & Pittet, A. (2000). Development of ochratoxin A during robusta (coffea canephora) coffee cherry drying. Journal of Agricultural Food and Chemistry, 48, 1358–1362.
G.H.D. van der Stegen / Food Control 14 (2003) 245–249 Burdaspal, P., & Legarda, T. (1998). Ocratoxina A en Muestras de Cafe Comercializado en Espana. Alimentaria (October), 31– 35. Coffee Statistics 1999 (2000). Nr 16, ISSN 1364-9086. ICO, London. Consumerorganisations (various years). Okotest Õ96, Õ00 and Õ01, Teste pour Vous Õ98 and Que Choisir Õ00. Frank, J. (1997). Toward the prevention of mould mediated quality loss. HACCP analysis of an outdoor process. In Proceedings of the 17th ASIC colloquium, Nairobi (pp. 61–68). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Frank, J. (1999a). HACCP and its mycotoxin control potential: an evaluation of ochratoxin A in coffee production. In Third joint FAO/WHO/UNEP international conference on mycotoxins (p. 34). Tunis 3–6 March. Frank, J. (1999b). Modelling and HACCP tools for coffee quality improvement. In Proceedings of the 18th ASIC colloquium, Helsinki (pp. 223–228). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Heilmann, W., Rehfeldt, A., & Rotzoll, F. (1999). Behaviour and reduction of ochratoxin A in green coffee beans in response to variuos processing methods. European Food Research and Technology, 209, 297–300. JECFA (2001). In 56th meeting, Geneva, 6–15 February 2001. Available: www.who.int/pcs/jecfa/Summary56.pdf. Jorgensen, K. (1998). Survey of pork, poultry, coffee, beer, and pulses for ochratoxin A. Food Additives and Contaminants, 15, 550– 554. Koch, M., Steinmeyer, S., Tiebach, R., Weber, R., & Weyerstahl, P. (1996). Bestimmung von Ochratoxin A in Roestkaffee. Deutsche Lebensmittel Rundschau, 92, 48–51. Maierhofer, P., Dietrich, R., & Maertlbauer, E. (1995). Detection of ochratoxin A in green and roasted coffee. In Proceedings of the 17th mycotoxin workshop (pp. 147–150). Micco, C., Grossi, M., Miraglia, M., & Brera, C. (1989). A study of the contamination by ochratoxin A of green and roasted coffee beans. Food Additives and Contaminants, 6, 333–339. National results from EU survey (1999). Dk, F, It, NL and Sw.
249
Otteneder, H., & Majerus, P. (2001). Mykotoxine, LebensmittelKontaminanten Nr. 1-Versuch einer Standortbestimmung. Deutsche Lebensmittel-Rundschau, 97, 334–338. Patel, S., Hazel, C., Winterton, A., & Gleadle, A. (1997). Survey of ochratoxin A in UK retail coffees. Food Additives and Contaminants, 14, 217–222. Pittet, A., Tornare, D., Huggett, A., & Viani, R. (1996). Liquid chromatogrphy determination of ochratoxin A in pure and adulterated soluble coffee using an immunoaffinity column cleanup procedure. Journal of Agricultural and Food Chemistry, 44, 3564–3569. Proceedings ASIC (1997). In Proceedings of the 17th ASIC colloquium, Nairobi (pp. 61–68 and 823–824). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Proceedings ASIC (1999). In Proceedings of the 18th ASIC colloquium, Helsinki (pp. 219–280). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Proceedings ASIC (2001). Highlights of the workshop ‘‘moisture management for mould prevention’’. In Proceedings of the 19th ASIC colloquium, Trieste, CD-ROM ISBN 2-90012-18-9. Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Tsubouchi, H., Terada, H., Yamamoto, K., & Sakabe, Y. (1988). Ochratoxin A found in commercial roast coffee. Journal of Agricultural and Food Chemistry, 36, 540–542. van der Stegen, G., Essens, P., & van der Lijn, J. (2001). Effect of roasting conditions on reduction of ochratoxin A in coffee. Journal of Agricultural and Food Chemistry, 49, 4713–4715. van der Stegen, G., Joerissen, U., Pittet, A., Saccon, M., Steiner, W., Vincenzi, M., Winkler, M., Zapp, J., & Schlatter, Chr. (1997). Screening of European coffee final products for occurrence of ochratoxin A (OTA). Food Additives and Contaminants, 14, 211– 216. Viani, R. (2002). Effect of processing on ochratoxin A (OTA) content of coffee. Mycotoxins and Food Safety, 189–193. Wilkens, J., & Joerissen, U. (1999). Abbau von Ochratoxin A bei der Production von Roestkaffee. In H. Rosner & P. Kielstein (Eds.), Proceedings of the 21st mykotoxin workshop, Jena, June 7–9 (pp. 245–251). Jena, Germany: BGVV.
Enhancement of coffee quality by mould prevention Gerrit H.D. van der Stegen
*
SaraLee/DE N.V, P.O. Box 2, 3500 CA Utrecht, Netherlands Received 11 November 2001; received in revised form 16 September 2002; accepted 17 September 2002
1. Introduction A description of the coffee production chain is presented together with an overview of the gathered relevant basic data. Based upon evaluation thereof the European coffee sector chose for a strategy of prevention to deal with the occurrence of mould growth. The project, which was developed under international co-operation, the ICO/FAO Mould Prevention Project, is described. Finally the overall results so far are presented.
The world production of coffee amounts to 110 million bags/year (60 kg bags, 6.6 million tons/year). About 90 million bags/year are exported and about half of them come to the EU. Maritime transport goes these days almost completely in sea-containers, either in bulk (21 ton/container) or in bags (18 ton/container). Per year around 1/4 million containers with coffee are arriving in the EU.
2. Description of coffee production chain Coffee is grown in over 50 countries around the world, all in the tropical region. Almost all of them are developing countries. Internationally traded coffee is produced almost completely from two different botanical species. About 2/3 of the coffee stems from Coffea arabica, mainly grown in Central and South America and in East Africa (the origin of this coffee). Another 1/3 comes from Coffea canephora robusta, mainly grown in Africa and Asia. Some countries export substantial amounts of both types, e.g. Brazil, Ecuador and India (Coffee Statistics 1999). Worldwide 3/4 of all coffee is produced by small farmers. In total an estimated 250 million people are dependent on coffee production in these countries. After harvesting mainly two different types of primary processing are used. These processes differ in the way the beans are separated out of the coffee berry. For arabicaÕs in areas where water is abundant mainly the so-called wet processing is practised. In areas with shortage in water and almost all robustaÕs are processed via the so-called natural or dry process. The wet process requires higher investments, is more labour intensive and generally brings a higher price.
*
Tel.: +31-30-297-91-11.
The export of coffee generates for the producing countries annual foreign exchange earnings of around 10 billion €/year. This makes coffee value-wise, after oil, the second largest export product from developing countries. Many producing countries depend heavily on coffee, some for up to 3/4 of their export earnings (Coffee Statistics 1999). Further processing of the coffee, like decaffeination and instant production, is done both in the producing countries and in the consuming countries. Production of roast (and ground) coffee is for reasons of freshness mostly done in/near to the country of consumption. The main countries of coffee consumption are by total volume USA, Germany, Japan and France and by per capita consumption the Scandinavian countries, Austria and the Netherlands. Regular R&G coffee covers about 3/4 of the European coffee consumption and instant coffee about 1/5.
0956-7135/03/$ - see front matter 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0956-7135(03)00009-4
246
G.H.D. van der Stegen / Food Control 14 (2003) 245–249
3. Occurrence of OTA and its fate in processing Mould growth can occur on a wide range of agricultural products, like cereals, grapes, and green coffee beans. For coffee the risk of mould growth exists at inappropriate drying of the green coffee beans/berries and at rewetting of the green coffee beans, e.g. due to condensation. Aspergillus ochraceus is capable of growing and producing of ochratoxin A (OTA) on partially dried/rewetted green coffee (Bucheli, Kanchanomai, Meyer, & Pittet, 2000; Frank, 1997, 1999a, 1999b; Viani, 2002). Till the last decade of the 20th century the general understanding was that OTA is degraded during coffee roasting. Occurrence of OTA in Japanese retail coffee samples was reported (Tsubouchi, Terada, Yamamoto, & Sakabe, 1988), the coffee sector then initiated a number of studies. Among these are several studies about the fate of OTA during processing of the coffee in the consuming countries (Blanc, Pittet, Munoz-Box, & Viani, 1998; Heilmann, Rehfeldt, & Rotzoll, 1999; van der Stegen, Essens, & van der Lijn, 2001), a survey on coffee final products on European markets (van der Stegen et al., 1997) and a fact finding pilot study (Frank, 1997, 1999a, 1999b). In the framework of the latter, expert mycologists from University of Surrey/UK and Tech. University of Denmark made field trips to producing countries, covering major coffee types and major primary processing methods. For decaffeination it was shown that 3/4 of the OTA present is removed by the extraction (Heilmann et al., 1999). In total nine studies about reduction during roasting are now published. Seven of them showed high percentages of OTA reduction up to 96% respectively almost complete. Two studies had deviating results showing almost no reduction, however these studies applied heating of the coffee beans clearly outside the range of normal coffee roasting. From the series of publications it can be concluded that the OTA is reduced by 3/4 during roasting, partly by physical removal with the chaff partly by not yet fully elucidated mechanisms (Micco, Grossi, Miraglia, & Brera, 1989; van der Stegen et al., 2001; Wilkens & Joerissen, 1999). The remainder of the OTA is mainly extracted with water (Blanc et al., 1998; van der Stegen et al., 1997). Studies on sorting of coffee to remove contaminated beans are still ongoing. Results obtained so far are not yet conclusive. Also a number of transport trials, registering temperature and humidity fluctuations in the container during transport have been done. The obtained results show high fluctuations during over-land transport, with risk for condensation particularly in the port of arrival. Such risk seems understandable considering that these containers are stuffed in the tropics and being transported and unloaded in the colder climates.
Since 1995 in total 985 results on regular R&G and 359 results about instant coffee (regular + decaf) have been published (Bresch, Urbanek, & Hell, 2000; Burdaspal & Legarda, 1998; Consumerorganisations, various years; Jorgensen, 1998; Koch, Steinmeyer, Tiebach, Weber, & Weyerstahl, 1996; Maierhofer, Dietrich, & Maertlbauer, 1995; National results from EU survey, 1999; Patel, Hazel, Winterton, & Gleadle, 1997; van der Stegen et al., 1997). The frequency distribution of all these results is given in the figure below, showing that 71% of the instants and 83% of the regular R&G samples fall in the category ‘‘<1 ppb’’.
4. Human exposure and effects of a regulatory limit In its February 2001 evaluation JECFA (JECFA, 2001, 56th meeting), estimated the mean total dietary intake of OTA to be 45 ng/kg b.w./week. Using for coffee a weighted mean of 0.86 ppb and a consumption of 170 g R&G/week (which is equals the high per capita consumption in Scandinavia, acc. Coffee Statistics 1999) it estimated coffeeÕs share in the total intake to be 4–7%. JECFA retained the previously established PTWI of 100 ng/kg body weight per week, pending results of ongoing studies. It recommended a further review of OTA in 2004. By consistently using a Ôweekly intakeÕ, JECFA signals that its concern with respect to OTA is its chronic toxicity. In its summary and conclusions document JECFA states that ‘‘no cases of acute intoxication in humans have been reported’’. From JECFAÕs concern about chronic toxicity it can be derived that particularly mean levels of intake should get focus. An incidental high level in a product, of course, contributes to the mean, but as the concern is not about acute toxicity, the focus should be more on the mean levels for the total population respectively the heavy users. A maximum limit for OTA in coffee can have a number of effects: • eliminating coffees with values above the limit from supply to the consumer; • changing the distribution curve below the limit value, with an actual drift up to the limit; • effecting the export earnings from producing countries. The effect of eliminating high values both on mean value of the remaining samples and on economies of producing countries can be estimated from the available data (will be shown below). The effect of the distribution curve drifting upwards to the limit is more difficult to estimate. With the curve now being very skewed to the
G.H.D. van der Stegen / Food Control 14 (2003) 245–249
lower end, it might easily raise the mean level of the remaining samples. It is important to be aware of such possibility. From the data sets for regular R&G and instant coffees, as shown in Fig. 1, the reduction of the mean OTA level by removal of the high values can be calculated and is shown in Fig. 2 (without taking into account any drift up to the limit). Coffee provides an estimated 4–7% of average human intake. Even if a regulatory limit were imposed removing 3% of coffee containing the highest amount of OTA, thus reducing the mean level reaching the consumer in coffee by 25–30% this actually will only result in a reduction in total mean human exposure of less than 2%. For the coffee growing countries, rejecting 3% from the coffee would induce for them a loss of export volume valued at 300 million €/year and will hit some producing countries very seriously, particularly those depending most strongly on coffee. At world wide 3% rejection, the most severely hit country will loose 1/4 of its total export earnings and six more countries will loose between 5% and 10% of their total export earnings (not just coffee). These arguments brought the coffee sector to set their strategy for prevention of mould growth instead of a regulatory limit.
Fig. 1. Distribution of published data on coffee samples over OTA levels (1995–2001).
247
5. ICO/FAO mould prevention project In a fact finding pilot study, commissioned by the European coffee sector, expert mycologists from University of Surrey/UK and Tech. University of Denmark made in 1996–1998 field trips to producing countries, covering major coffee types and major primary processing methods. First guidelines for preventing mould growth were drafted during an international coffee conference 1997 in Nairobi (Proceedings ASIC, 1997). Since then a project for enhancement of coffee quality through prevention of mould formation was developed to cover all coffee producing countries. The International Coffee Organisation (ICO/London, an intergovernmental body) took the role of supervisory body and FAO/Rome the role of project executing agency. The project is budgeted with US$5.6 million and runs from 1999 to 2004. Main funders are the Common Fund for Commodities, the Dutch government and the European coffee sector. The project uses a two step approach. In the Ôfirst waveÕ a number of Ôlead countriesÕ build up local expertise, local HACCP-like models, develop training material and start with the training. The first country to start was Uganda (1999). India, Kenya, Indonesia, Brazil, Colombia and recently also Cote dÕIvoire are the other Ôlead countriesÕ. In a Ôsecond waveÕ of Ôsurrounding countriesÕ dissemination through training and implementation of GAP/GMP will be done. Ecuador, Ethiopia, Nicaragua and Vietnam are likely to enter soon into this step (Viani, 2002). Several producing countries have also developed substantial own activities on mould prevention in parallel to the formal ICO/FAO prevention project. All activities geared to the common goal will help. After the first meeting during the 1997 Nairobi coffee conference, further mould prevention Workshops took place in Helsinki 1999 and Trieste 2001 (Proceedings ASIC, 1999, 2001). Recently updated guidelines for ‘‘DoÕs and DonÕts’’ in mould prevention have been issued under the joint headings of ICO/London, FAO/ Rome and the European OTA Taskforce (Proceedings ASIC, 2001).
6. Evaluation of status so far
Fig. 2. Reduction of mean OTA level by removal of high values (without drift up to limit).
To evaluate any developments in the mean OTA levels of coffee sold on the European market all data from random/representative sampling published in scientific journals or published by consumer organisations or available from the 1999 EU national Food Inspections screening are fed into a data base (Bresch et al., 2000; Burdaspal & Legarda, 1998; Consumerorganisations, various years; Jorgensen, 1998; Koch et al., 1996; Maierhofer et al., 1995; National results from EU
248
G.H.D. van der Stegen / Food Control 14 (2003) 245–249
Table 1 Mean OTA levels in regular R&G coffees over the recent years (in ppb, with number of samples between brackets) Year of sampling
Germany
France
EU-memberstates (all together)
Mean concentration in beverage (lg/litre)a
1995 1996–2000
0.7 (140) 0.5 (220)
0.6 (40) 0.3 (62)b
0.8 (492) 0.5 (492)b
0.03 0.02
a
At 40 g of coffee/litre of water as a usual brewing strength. Among the French data there is uncertainty about two samples with identical code, but one labelled ‘‘ground’’, reported to have quite different results. In above table the result for the ground sample is taken, as the difference likely relates to mycotoxin inhomogeneity. b
survey, 1999; Patel et al., 1997; van der Stegen et al., 1997). The collected data allow for regular R&G coffee the evaluation as given in Table 1, showing a substantial decrease in mean OTA levels over the recent years. From the total 359 available data on instant coffee a similar time trend evaluation cannot be made, as the data are very much clustered. Nearly half of these data, 167 samples, originate from one country-year combination (UK 1995). The mean OTA level over all 359 samples of instant coffee amounts 1.4 ppb. Another complication with instant coffees can be the occurrence of adulteration with non-coffee-bean materials. Coffee beans themselves contain hardly any xylose (<0.3%). There are indications that OTA levels in products sold as instant coffee are correlated with elevated xylose levels, which would turn the issue from a contaminated coffee beans issue into a fraudulent raw materials issue (Pittet, Tornare, Huggett, & Viani, 1996). The question at the end of course is what does this all mean in the cup as consumed? From the data in Table 1 and the overall mean in instant coffees can be derived that the mean OTA level in brewed regular coffee (around 40 g coffee/litre) reduced in the period Õ95 to Õ01 from 0.03 to 0.02 lg/ litre and that the mean level for coffee prepared from instant (around 14 g/litre) amounts also to 0.02 lg/ litre, which is low compared to other concerned drinks (Otteneder & Majerus, 2001).
7. Summary Coffee is grown in over 50 countries around the world. Almost all of them are developing countries. The export of coffee generates for these countries annual foreign exchange earnings of around 10 million €/year. Mould growth can occur on several agricultural products, like cereals, grapes, and green coffee beans. For coffee the risk of mould growth exists at inappropriate drying of the green coffee beans/berries and at rewetting of the green coffee beans. A. ochraceus is capable of growing and producing of OTA on partially dried/rewetted green coffee. During decaffeination of green coffee and also at roasting of green coffee 3/4 of the OTA is removed.
Published data about occurrence of OTA in instants and regular R&G coffees show a distribution very much skewed to the lower levels resp. below detection limit. Percentages of 70–85% of the samples are in the category ‘‘<1 ppb’’. JECFA estimated, in its February 2001 evaluation, that the mean total dietary intake of OTA was 45 ng/kg b.w./week and that the coffeeÕs share in the total intake was 4–7%. It used for coffee a weighted mean of 0.86 ppb. Applying the instrument of maximum limits on coffee will induce some lowering of mean level plus economic damage in producer countries, in some countries very seriously. A possible reduction of 25–30% in the mean OTA level is estimated from the current distribution curves. A change in the skewedness of the distribution, e.g. by a drift up to the limit, can easily outbalance this effect. The effect on total exposure would anyhow be very small (<2%), as coffee is only a minor contributor in OTA. These arguments brought the coffee sector to set their strategy for prevention of mould growth instead of a regulatory limit. With the help of international organisations, FAO/ Rome, ICO/London and CFC/Amsterdam, a worldwide mould prevention project was initiated which runs from 1999 to 2004. In parallel communication channels in the coffee sector have been used to raise awareness for the issue in the whole coffee world. Occurrence data collected in recent years already show a substantial decrease in the mean OTA level for R&G coffee, at least as big as what could be achieved by regulatory limits. In the beverage as consumed the mean level has gone down from 0.03 to 0.02 lg/litre, which is a low level compared to some other concerned drinks.
References Blanc, M., Pittet, A., Munoz-Box, R., & Viani, R. (1998). Behavior of ochratoxin A during green coffee roasting and soluble coffee manufacture. Journal of Agricultural and Food Chemistry, 46, 673–675. Bresch, H., Urbanek, M., & Hell, K. (2000). Ochratoxin A in coffee, tea and beer. Archiv fur Lebensmittelhygiene, 51, 81–128. Bucheli, P., Kanchanomai, C., Meyer, I., & Pittet, A. (2000). Development of ochratoxin A during robusta (coffea canephora) coffee cherry drying. Journal of Agricultural Food and Chemistry, 48, 1358–1362.
G.H.D. van der Stegen / Food Control 14 (2003) 245–249 Burdaspal, P., & Legarda, T. (1998). Ocratoxina A en Muestras de Cafe Comercializado en Espana. Alimentaria (October), 31– 35. Coffee Statistics 1999 (2000). Nr 16, ISSN 1364-9086. ICO, London. Consumerorganisations (various years). Okotest Õ96, Õ00 and Õ01, Teste pour Vous Õ98 and Que Choisir Õ00. Frank, J. (1997). Toward the prevention of mould mediated quality loss. HACCP analysis of an outdoor process. In Proceedings of the 17th ASIC colloquium, Nairobi (pp. 61–68). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Frank, J. (1999a). HACCP and its mycotoxin control potential: an evaluation of ochratoxin A in coffee production. In Third joint FAO/WHO/UNEP international conference on mycotoxins (p. 34). Tunis 3–6 March. Frank, J. (1999b). Modelling and HACCP tools for coffee quality improvement. In Proceedings of the 18th ASIC colloquium, Helsinki (pp. 223–228). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Heilmann, W., Rehfeldt, A., & Rotzoll, F. (1999). Behaviour and reduction of ochratoxin A in green coffee beans in response to variuos processing methods. European Food Research and Technology, 209, 297–300. JECFA (2001). In 56th meeting, Geneva, 6–15 February 2001. Available: www.who.int/pcs/jecfa/Summary56.pdf. Jorgensen, K. (1998). Survey of pork, poultry, coffee, beer, and pulses for ochratoxin A. Food Additives and Contaminants, 15, 550– 554. Koch, M., Steinmeyer, S., Tiebach, R., Weber, R., & Weyerstahl, P. (1996). Bestimmung von Ochratoxin A in Roestkaffee. Deutsche Lebensmittel Rundschau, 92, 48–51. Maierhofer, P., Dietrich, R., & Maertlbauer, E. (1995). Detection of ochratoxin A in green and roasted coffee. In Proceedings of the 17th mycotoxin workshop (pp. 147–150). Micco, C., Grossi, M., Miraglia, M., & Brera, C. (1989). A study of the contamination by ochratoxin A of green and roasted coffee beans. Food Additives and Contaminants, 6, 333–339. National results from EU survey (1999). Dk, F, It, NL and Sw.
249
Otteneder, H., & Majerus, P. (2001). Mykotoxine, LebensmittelKontaminanten Nr. 1-Versuch einer Standortbestimmung. Deutsche Lebensmittel-Rundschau, 97, 334–338. Patel, S., Hazel, C., Winterton, A., & Gleadle, A. (1997). Survey of ochratoxin A in UK retail coffees. Food Additives and Contaminants, 14, 217–222. Pittet, A., Tornare, D., Huggett, A., & Viani, R. (1996). Liquid chromatogrphy determination of ochratoxin A in pure and adulterated soluble coffee using an immunoaffinity column cleanup procedure. Journal of Agricultural and Food Chemistry, 44, 3564–3569. Proceedings ASIC (1997). In Proceedings of the 17th ASIC colloquium, Nairobi (pp. 61–68 and 823–824). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Proceedings ASIC (1999). In Proceedings of the 18th ASIC colloquium, Helsinki (pp. 219–280). Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Proceedings ASIC (2001). Highlights of the workshop ‘‘moisture management for mould prevention’’. In Proceedings of the 19th ASIC colloquium, Trieste, CD-ROM ISBN 2-90012-18-9. Association Scientifique Internationale du Cafe, 3 Rue de Copenhague, Paris, France. Tsubouchi, H., Terada, H., Yamamoto, K., & Sakabe, Y. (1988). Ochratoxin A found in commercial roast coffee. Journal of Agricultural and Food Chemistry, 36, 540–542. van der Stegen, G., Essens, P., & van der Lijn, J. (2001). Effect of roasting conditions on reduction of ochratoxin A in coffee. Journal of Agricultural and Food Chemistry, 49, 4713–4715. van der Stegen, G., Joerissen, U., Pittet, A., Saccon, M., Steiner, W., Vincenzi, M., Winkler, M., Zapp, J., & Schlatter, Chr. (1997). Screening of European coffee final products for occurrence of ochratoxin A (OTA). Food Additives and Contaminants, 14, 211– 216. Viani, R. (2002). Effect of processing on ochratoxin A (OTA) content of coffee. Mycotoxins and Food Safety, 189–193. Wilkens, J., & Joerissen, U. (1999). Abbau von Ochratoxin A bei der Production von Roestkaffee. In H. Rosner & P. Kielstein (Eds.), Proceedings of the 21st mykotoxin workshop, Jena, June 7–9 (pp. 245–251). Jena, Germany: BGVV.