Influence of roasting and different brewing processes on ochratoxin A content in coffee determined by high-performance liquid chromatography-fluorescence detection (HPLC-FLD)

A rapid and reliable procedure has been developed for the determination of ochratoxin A (OTA) in green androasted coffee. The method consists of extraction of the sample with methanol–5% aqueous sodium hydrogencarbonate/1% PEG8000 (20:80), followed by immunoaffinity column (IAC) clean-up and, finally, highperformanceliquid chromatography (HPLC) determination with fluorimetric detection. Mean recoveries forgreen and roasted coffee spiked at different levels ranging from 94 and 105% were obtained. The limit ofdetermination (S/N¼3) was 0.032 ng g 1 and the precision (within-laboratory relative standard deviation) was6%. The method described has been used to assess the influence of roasting and different brewing processes onOTA content in commercial lots of green and roasted coffee. The results provided evidence that roasting led to asignificant drop on OTA levels (65–100%). Also, the way coffee is prepared affects the OTA content: brewingusing a Moka Express (Italian coffee) led to a significant reduction of OTA concentration (50–75%) since hotwater stays in contact with coffee for a short time. On the contrary, Turkish coffee-making (infusion for about10 min) cause poor reduction in OTA.