Aflatoxins in bulk and pre-packed pistachios sold in Spain and effect of roasting

The occurrence of aflatoxins in national and imported pistachios available in Aragón (NE Spain), purchased from commercial outlets during 2007, was surveyed. Thirty-two samples of roasted pistachios were analyzed for aflatoxins by immunoaffinity cleanup with liquid chromatography and fluorescence detection using post-column photochemical derivatization. Results showed that the incidence of aflatoxin B1 and B2 in pre-packed pistachios was 19% and 6%, while in bulk pistachios was 50% and 12.5%, respectively. All positive samples originated from Iran, while pistachios from USA, Turkey and Spain tested negative for aflatoxins. The low degree of contamination ranged from 0.12 to 0.29 μg/kg, and no sample exceeded the maximum permitted level for aflatoxins in pistachio nuts. Naturally occurring aflatoxin B1 was not noticeably reduced by commercial roasting at 120 °C for 20 min.