27 agosto 2007

Effect of operating conditions on ochratoxin A extraction from roasted coffee

On “Food Additives and Contaminants” (volume 24, issue 7, pp. 730-734) was published an article related to a study carried by French (Montpellier) and African (Cameroun) partners, which demostrated that operating conditions affect ochratoxin A (OTA) extraction from roasted coffee. This implies that contamination results can change very much between methods.
Three extraction parameters were studied for roasted coffee (acid, alkalin, neutral), with different times (5, 20, 30, 40, 50, 60 and 80 minutes) and temperatures (RT/23°C, 60°C and 85°C).The alkaline solvent used in the method recommended by the European Union extracted OTA better (compared to neutral and acid extraction), but a maximum content was obtained at 60°C after 50 min.
At least a 100% improvement in extraction was obtained when compared with the European Union usual quantification method that is carried out at ambient temperature. These results were verified in double-extraction experiments showing that OTA is not completely extracted by this method. Confirmation was obtained by comparison of extraction methods on several commercial samples of roasted coffee. Maybe the official method should be revised.

(Authors: P. Mounjouenpou, N. Durand, B. Guyot, J.P. Guiraud)