期刊
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
卷 63, 期 3, 页码 1029-1034出版社
AMER CHEMICAL SOC
DOI: 10.1021/jf504254q
关键词
coffee; ochratoxin A; fumonisin; QuEChERS; mixex-mode reversed phase-anion exchange; isotope dilution; LC-MS/MS; Aspergillus niger
资金
- Danish Veterinary and Food Administration [Cocktail- 2011-14]
- EEC project MycoRed [KBBE-2007-222690-2]
A method was developed for simultaneous determination of the mycotoxins: ochratoxin A (OTA) and fumonisins B-2 (FB2), B-4 (FB4), and B-6 (FB6) in green, roasted, and instant coffee. Extraction was performed by QuEChERS (quick, easy, cheap, effective, rugged, and safe) under acidic conditions followed by mixed-mode reversed phase-anion exchange solid phase extraction. OTA and FB2 were detected at levels down to 0.5 and 2 mu g/kg by UHPLC-MS/MS and quantitated via isotope dilution using U-C-13-labeled FB2 and OTA as internal standards. Mixing 20% isopropanol in the acetonitrile of the acidic UHPLC gradient system increased the signal intensity by 50% and decreased the ion-suppression with 50-75% in roasted coffee samples. About half of the roasted coffee samples (n = 57, from 9 countries) contained detectable levels of OTA, however, with only 5 samples above the EU regulatory limit of 5 mu g/kg and the highest with 21 mu g/kg. None of the 25 instant coffee samples contained OTA above the EU regulatory level of 10 mu g/kg. Nonetheless, the toxin could be detected in 56% of the analyzed instant coffee samples. Fumonisins were not detected in any of the roasted or instant coffee samples (n = 82). However, in the green coffee samples (n = 18) almost half of the samples were positive with a maximum value of 164 mu g/kg (sum of FB2, FB4, and FB6). This discrepancy between green coffee and processed coffees indicated that the fumonisins decompose during the roasting process, which was confirmed in roasting experiments. Here fumonisins could not be detected after roasting of the green, 164 mu g/kg coffee, sample. Under the same conditions, OTA was reduced from 2.4 to 0.5 mu g/kg.
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