Food Chemistry 129 (2011) 1325–1326
Contents lists available at ScienceDirect
Food Chemistry journal homepage: www.elsevier.com/locate/foodchem
Letter to the Editor Response to the article ‘‘Occurrence of furan in coffee from Spanish market: Contribution of brewing and roasting’’
Sir, I refer to a recent article (Food Chemistry, 126 (2011) 1527– 1532) in your journal by M.S. Altaki, F.J. Santos, M.T. Galceran, in which the authors report the amounts of furan in different coffees, including regular coffee brews from the Spanish market as well as espresso coffees obtained with the commercial Nespresso coffee capsule system. The authors have also studied the impact of roasting conditions on furan formation in roasted coffee. The amount of furan ingested through drinking coffee depends on several factors, such as the coffee brewing and preparation methods, strength of the cup (powder to water ratio), and final portion/cup size (EFSA, 2010; Guenther, Hoenicke, Biesterveld, Gerhard-Rieben, & Lantz, 2010). In their study, the authors identified relatively higher amounts of furan in espresso brews, which is not new information and has been established previously (Crews, 2009; EFSA, 2010; Guenther et al., 2010; Kuballa, Stier, & Strichow, 2005; Zoller, Sager, & Reinhard, 2007). It is also well known that semi or fully automatic espresso coffee machines produce brews with relatively higher amounts of furan versus manual brewing, because a closed system favours retention of aroma, and produces brews with a higher ratio of coffee powder to water, i.e. a lower dilution factor, and hence more furan (EFSA, 2010; Kuballa et al., 2005; Zoller et al., 2007). However, for reliable intake assessments an equally important factor besides the amount of furan in the brew is the portion or cup size. Altaki, Santos, and Galceran (2011) express their data in terms of concentration (ng furan per mL brewed coffee), which does not take into consideration portion
size. The volume of preparation of espresso coffees was arbitrarily set at 60 mL whereas the volume of preparation of Nespresso coffees was stipulated at 40 mL. Calculation of their data in terms of furan amount per cup is a far better measure of intake, and the ranges then equate to 2.6–8.8 and 4.7–9.8 lg furan per cup for espresso and Nespresso coffees (espresso range), respectively. As depicted in Table 1 below, these ranges are comparable with furan data published in the literature, (Crews, 2009; Kuballa et al., 2005; Zoller et al., 2007). The authors have also studied the impact of roasting on the formation of furan. As already shown by Guenther et al. (2010), furan is formed as a function of the ‘‘degree of roast’’ and ‘‘roast time’’. These parameters are defined within narrow ranges to afford coffees with the required aroma and taste profiles. The recommendations of Altaki et al. (2011) to apply ‘‘gently roasting conditions’’ are premature and should not be made in isolation focusing only on furan, as they may lead to higher concentrations of other undesired compounds (Guenther et al., 2010). A further comment is that the authors refer to an acceptable daily intake (ADI) for furan of 2 lg/kg bw. This ADI was proposed by T. Kuballa (Veterinary Investigations Office, Karlsruhe, Germany) during the Joint DG Sanco/EFSA/DG JRC Workshop on ‘‘Furan in Food’’ held in Brussels on the 19th May 2005, and described as a ‘‘hypothetic ADI’’, using the standard safety factor of 1000 and a No Observed Adverse Effect Level (NOAEL) of 2 mg/kg bw, based on furan hepatocarcinogenicity (bile duct tumours) in a 2 year rodent bioassay study. The evidence available today points towards the involvement of the genotoxic metabolite cis-2-butene-1,4-dial in furan-induced carcinogenesis (Bolger, Tao, & Dinovi, 2009), and therefore in this case the establishment of an ADI is not an accepted practice.
Table 1 Furan amounts in beverages prepared with coffee machines and expressed on a cup basis. Machine description
Coffee type
Averaged intake (lg furan per cup) (n = number of analyses)
References
Vending machine (for roasted beans, i.e. bean to cup vendor)
Espresso
8.5 (n = 5)a
Crews (2009)
Coffee machine (for soluble powders) Coffee machine (semi or fully automated) Vending machine Coffee machine (fully automated) a b c d
a
Latte Regular Regular Espresso
47.7 (n = 4) 56.5 (n = 3)a 8.2 (n = 4)a 3.3 (n = 3)a
Espressob Regularc Regularc Espressob
8.3 9.8 7.5 5.1
Regulard
13.2 (n = 6)
Five analyses conducted per sample set. Based on a volume of 65 mL for espresso coffees. Based on a volume of 130 mL. Based on a volume of 150 mL.
0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.05.056
(n = 2) (n = 2) (n = 1) (n = 1)
Zoller et al. (2007)
Kuballa et al. (2005)
1326
Letter to the Editor / Food Chemistry 129 (2011) 1325–1326
In conclusion, the work published by Altaki et al. (2011) adds little to existing studies and does not raise any new concerns. To date, no measures have been identified to mitigate furan without impacting product quality and/or safety, and the Confederation of the European Food and Drink Industries (CIAA) is addressing the issue of furan and other process contaminants in a joint, non-competitive effort. References Altaki, M. S., Santos, F. J., & Galceran, M. T. (2011). Occurrence of furan in coffee from Spanish market: Contribution of brewing and roasting. Food Chemistry, 126, 1527–1532. Bolger, P. M., Tao, S. S.-H., & Dinovi, M. (2009). Hazards of dietary furan. In R. H. Stadler & D. Lineback (Eds.), Processed-induced food toxicants (pp. 117–133). Hoboken, NJ: J. Wiley & Sons Inc.. Crews, C. (2009). Consumer exposure to furan from heat – processed foods and kitchen air. Scientific report submitted to EFSA. Available online: http:// www.efsa.europa.eu/fr/scdocs/doc/30e.pdf (accessed 6 May 2011). European Food Safety Authority 2010. Update of results on the monitoring of furan levels in food. EFSA Journal 8(7), 1702. [p. 18]. doi:10.2903/
j.efsa.2010.1702. Available online: www.efsa.europa.eu/(accessed 6 May 2011). Guenther, H., Hoenicke, K., Biesterveld, S., Gerhard-Rieben, E., & Lantz, I. (2010). Furan in coffee: Pilot studies on formation during roasting and losses during production steps and consumer handling. Food Additives and Contaminants, 27, 283–290. Kuballa, T., Stier, S., & Strichow, N. (2005). Furan in Kaffee und Kaffeegetränken. Deutsche Lebensmittel-Rundschau: Zeitschrift für Lebensmittelkunde und Lebensmittelrecht, 101, 229–235. Zoller, O., Sager, F., & Reinhard, H. (2007). Furan in food: headspace method and product survey. Food Additives and Contaminants, 24(Suppl. 1), 91–107.
Richard H. Stadler Nestlé Product Technology Centre, CH 1350 Orbe, Switzerland Tel.: +41 24 442 7073. E-mail address: [email protected]
Contents lists available at ScienceDirect
Food Chemistry journal homepage: www.elsevier.com/locate/foodchem
Letter to the Editor Response to the article ‘‘Occurrence of furan in coffee from Spanish market: Contribution of brewing and roasting’’
Sir, I refer to a recent article (Food Chemistry, 126 (2011) 1527– 1532) in your journal by M.S. Altaki, F.J. Santos, M.T. Galceran, in which the authors report the amounts of furan in different coffees, including regular coffee brews from the Spanish market as well as espresso coffees obtained with the commercial Nespresso coffee capsule system. The authors have also studied the impact of roasting conditions on furan formation in roasted coffee. The amount of furan ingested through drinking coffee depends on several factors, such as the coffee brewing and preparation methods, strength of the cup (powder to water ratio), and final portion/cup size (EFSA, 2010; Guenther, Hoenicke, Biesterveld, Gerhard-Rieben, & Lantz, 2010). In their study, the authors identified relatively higher amounts of furan in espresso brews, which is not new information and has been established previously (Crews, 2009; EFSA, 2010; Guenther et al., 2010; Kuballa, Stier, & Strichow, 2005; Zoller, Sager, & Reinhard, 2007). It is also well known that semi or fully automatic espresso coffee machines produce brews with relatively higher amounts of furan versus manual brewing, because a closed system favours retention of aroma, and produces brews with a higher ratio of coffee powder to water, i.e. a lower dilution factor, and hence more furan (EFSA, 2010; Kuballa et al., 2005; Zoller et al., 2007). However, for reliable intake assessments an equally important factor besides the amount of furan in the brew is the portion or cup size. Altaki, Santos, and Galceran (2011) express their data in terms of concentration (ng furan per mL brewed coffee), which does not take into consideration portion
size. The volume of preparation of espresso coffees was arbitrarily set at 60 mL whereas the volume of preparation of Nespresso coffees was stipulated at 40 mL. Calculation of their data in terms of furan amount per cup is a far better measure of intake, and the ranges then equate to 2.6–8.8 and 4.7–9.8 lg furan per cup for espresso and Nespresso coffees (espresso range), respectively. As depicted in Table 1 below, these ranges are comparable with furan data published in the literature, (Crews, 2009; Kuballa et al., 2005; Zoller et al., 2007). The authors have also studied the impact of roasting on the formation of furan. As already shown by Guenther et al. (2010), furan is formed as a function of the ‘‘degree of roast’’ and ‘‘roast time’’. These parameters are defined within narrow ranges to afford coffees with the required aroma and taste profiles. The recommendations of Altaki et al. (2011) to apply ‘‘gently roasting conditions’’ are premature and should not be made in isolation focusing only on furan, as they may lead to higher concentrations of other undesired compounds (Guenther et al., 2010). A further comment is that the authors refer to an acceptable daily intake (ADI) for furan of 2 lg/kg bw. This ADI was proposed by T. Kuballa (Veterinary Investigations Office, Karlsruhe, Germany) during the Joint DG Sanco/EFSA/DG JRC Workshop on ‘‘Furan in Food’’ held in Brussels on the 19th May 2005, and described as a ‘‘hypothetic ADI’’, using the standard safety factor of 1000 and a No Observed Adverse Effect Level (NOAEL) of 2 mg/kg bw, based on furan hepatocarcinogenicity (bile duct tumours) in a 2 year rodent bioassay study. The evidence available today points towards the involvement of the genotoxic metabolite cis-2-butene-1,4-dial in furan-induced carcinogenesis (Bolger, Tao, & Dinovi, 2009), and therefore in this case the establishment of an ADI is not an accepted practice.
Table 1 Furan amounts in beverages prepared with coffee machines and expressed on a cup basis. Machine description
Coffee type
Averaged intake (lg furan per cup) (n = number of analyses)
References
Vending machine (for roasted beans, i.e. bean to cup vendor)
Espresso
8.5 (n = 5)a
Crews (2009)
Coffee machine (for soluble powders) Coffee machine (semi or fully automated) Vending machine Coffee machine (fully automated) a b c d
a
Latte Regular Regular Espresso
47.7 (n = 4) 56.5 (n = 3)a 8.2 (n = 4)a 3.3 (n = 3)a
Espressob Regularc Regularc Espressob
8.3 9.8 7.5 5.1
Regulard
13.2 (n = 6)
Five analyses conducted per sample set. Based on a volume of 65 mL for espresso coffees. Based on a volume of 130 mL. Based on a volume of 150 mL.
0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.05.056
(n = 2) (n = 2) (n = 1) (n = 1)
Zoller et al. (2007)
Kuballa et al. (2005)
1326
Letter to the Editor / Food Chemistry 129 (2011) 1325–1326
In conclusion, the work published by Altaki et al. (2011) adds little to existing studies and does not raise any new concerns. To date, no measures have been identified to mitigate furan without impacting product quality and/or safety, and the Confederation of the European Food and Drink Industries (CIAA) is addressing the issue of furan and other process contaminants in a joint, non-competitive effort. References Altaki, M. S., Santos, F. J., & Galceran, M. T. (2011). Occurrence of furan in coffee from Spanish market: Contribution of brewing and roasting. Food Chemistry, 126, 1527–1532. Bolger, P. M., Tao, S. S.-H., & Dinovi, M. (2009). Hazards of dietary furan. In R. H. Stadler & D. Lineback (Eds.), Processed-induced food toxicants (pp. 117–133). Hoboken, NJ: J. Wiley & Sons Inc.. Crews, C. (2009). Consumer exposure to furan from heat – processed foods and kitchen air. Scientific report submitted to EFSA. Available online: http:// www.efsa.europa.eu/fr/scdocs/doc/30e.pdf (accessed 6 May 2011). European Food Safety Authority 2010. Update of results on the monitoring of furan levels in food. EFSA Journal 8(7), 1702. [p. 18]. doi:10.2903/
j.efsa.2010.1702. Available online: www.efsa.europa.eu/(accessed 6 May 2011). Guenther, H., Hoenicke, K., Biesterveld, S., Gerhard-Rieben, E., & Lantz, I. (2010). Furan in coffee: Pilot studies on formation during roasting and losses during production steps and consumer handling. Food Additives and Contaminants, 27, 283–290. Kuballa, T., Stier, S., & Strichow, N. (2005). Furan in Kaffee und Kaffeegetränken. Deutsche Lebensmittel-Rundschau: Zeitschrift für Lebensmittelkunde und Lebensmittelrecht, 101, 229–235. Zoller, O., Sager, F., & Reinhard, H. (2007). Furan in food: headspace method and product survey. Food Additives and Contaminants, 24(Suppl. 1), 91–107.
Richard H. Stadler Nestlé Product Technology Centre, CH 1350 Orbe, Switzerland Tel.: +41 24 442 7073. E-mail address: [email protected]
