Method of Ochratoxin A Determination in Beans Applied to Samples Collected in the Republic of Croatia

Ochratoxin A (OTA) is a common contaminant of cereals and other commodities of animal and vegetable origin all round the world. Its nephrotoxic and carcinogenic properties are well established in experimental animals. Beans (Phaseolus vulgaris) are common food in our country, especially in winter period, but the data on OTA contamination of beans are rather scarce. The aim of this study was to analyze the OTA concentration in naturally contaminated beans with a more sensitive method than in previous studies. During fall 2001, bean samples (N=45) were collected in 13 counties of Croatia and stored (– 20 oC) until analyzed. Samples were cleaned up by means of immunoaffinity columns (OchraTest, Vicam) and OTA analyses were performed on HPLC (Varian, USA) with fluorescence detection. Standard curve prepared from OTA-spiked samples in the concentration range 0.25 to 5.0 mg/kg was linear (r2 = 0.9982). Detection limit of method was 0.25 mg/kg, reproducibility (day to day precision) expressed as RSD was 5.5 %. Such a low detection limit enabled the detection of OTA in 42 % of analyzed bean samples in the range of 0.25 to 0.92 mg/kg. The mean OTA concentration in positive samples was 0.39 &plusmn ; ; 0.21 mg/kg (mean &plusmn ; ; SD). Such a low concentration of OTA in beans does not represent a significant origin of human exposure to OTA, but due to the very long half-life of OTA in humans (35.55 days), it may contribute to the exposure to OTA from other commodities.