Simultaneous determination of aflatoxin B1 and ochratoxin A and their natural occurrence in Mediterranean virgin olive oil.

Olive oil, the most important dietary fat source of the Mediterranean diet, can be contaminated by mycotoxins. An efficient analytical method for the simultaneous determination of aflatoxin B1 (AFB1) and ochratoxin A (OTA) in olive oil is reported. Thirty commercial samples of virgin olive oil, purchased in olive-press plants and supermarkets in southern Italy and North Africa, were analysed to verify the analytical procedure and monitor mycotoxin contamination. A simple, rapid and economic method was set up and tested for both the extractive step and the clean-up procedures for simultaneous AFB1 and OTA determination in olive oil. Data obtained showed that OTA was detected with high frequency (80%) in samples from both geographical areas (up to 17.0 ng g-1), while AFB1 was found from three of four samples from North Africa (up to 2.4 ng g-1). In addition, 'not labelled' oil samples proved to be more contaminated by OTA then 'labelled' samples (mean values of 2.47 and 0.66 ng g-1, respectively). These findings indicate that olive oil can be significantly contaminated by mycotoxins and confirm that a scrupulous application of European Regulation 1019/2002 (European Commission 2002), which prohibits the sale of non-labelled olive oil, is strongly recommended. Conventional qualitative parameters such as peroxide number, spectrophotometric evaluation and acid values were not correlated with mycotoxin occurrence.