Yoghurt from cow's milk artificially contaminated with aflatoxin M1 (AFM1) at levels of 0.050 and 0.100 g l(-1) was fermented to reach pHs 4.0 and 4.6. Yoghurt fermented to pH 4.6 was also used for preparing strained yoghurt. Yoghurts were stored at 4 degrees C for up to 4 weeks. Analysis of AFM1 in milk, yoghurt, strained yoghurt and yoghurt whey was carried out using immunoaffinity column extraction and liquid chromatography coupled with fluorometric detection. AFM1 levels in yoghurt samples showed a significant decrease (p < 0.01) compared with those initially added to milk. Growth of culture lactic acid bacteria was not affected in the AFM1 contaminated yoghurts, with the exception of Streptococcus thermophilus that showed a significantly (p < 0.01) lower increase in the yoghurt containing the toxin at high concentration. Following fermentation, AFM1 was significantly lower (p < 0.01) in yoghurts with pH 4.0 than in yoghurts with pH 4.6 at both contamination levels. During refrigerated storage, AFM1 was rather more stable in yoghurts with pH 4.6 than with pH 4.0. The percentage loss of the initial amount of AFM1 in milk was estimated at about 13 and 22% by the end of the fermentation, and 16 and 34% by the end of storage for yoghurts with pHs 4.6 and 4.0, respectively. The percentage distribution ratio of AFM1 in strained yoghurt/yoghurt whey of the initial toxin present in the yoghurt was about 90/10 and 87/13 for the lower and the higher contamination levels, respectively.

From December 1999 to May 2000, 114 samples of pasteurized, ultrahigh temperature-treated (UHT) and concentrated milk were collected in supermarkets, whereas 52 raw milk samples from cow, sheep and goat were obtained from different milk producers all over Greece. Sample collection was repeated from December 2000 to May 2001 and concerned 54 samples of pasteurized milk, 23 samples of bulk-tank raw milk and 55 raw milk samples from cow, sheep and goat. The total number of samples analysed for aflatoxin M(1) (AFM(1)) contamination by immunoaffinity column extraction and liquid chromatography was 297. In the first sampling, the incidence rates of AFM(1) contamination in pasteurized, UHT, concentrated and cow, sheep and goat raw milk were 85.4, 82.3, 93.3, 73.3, 66.7 and 40%, respectively, with only one cow raw milk and two concentrated milk samples exceeding the EU limit of 50 ng l(-1). In the second sampling, the incidence rates of AFM(1) contamination in pasteurized, bulk-tank and cow, sheep and goat raw milk were 79.6, 78.3, 64.3, 73.3 and 66.7%, respectively, with only one cow and one sheep raw milk samples exceeding the limit of 50 ng l(-1). The results suggest that the current regulatory status in Greece is effective.

Telemes cheeses were produc ed using m ilk that was artiWcially-c ontam inated with aXatoxin M 1 at the levels of 0.05 0 and 0.10 0 ·g/ l. The cheeses produc ed in the two cheese-m aking trials were allowed to ripen for 2 months and stored for an addition al 4 months to sim ulate com mercial produc tion of Telem es cheese. Concentration s of aXatoxin M 1 in whey, curd, brine, and the produc ed cheeses were determined at intervals by liquid chromatogra phy and Xuorometric detection coupled with imm unoaYnity column extraction. Concentration s of aXatoxin M 1 in the produc ed curds were found to be 3.9 and 4.4 times highe r than those in milk, whereas concentration s in whey were lower than those in curd and milk. AXatoxin M 1 was present in cheese at highe r concentration s at the beginning than at the end of the ripening/storage period, and it declined to concentrations 2.7 and 3.4 times highe r than those initiall y present in m ilk by the end of the sixth month of storage. Concentration s of aXatoxin M 1 in brine started low and increased by the end of the ripening / storage period but only a portio n of the am ounts of aXatoxin M 1 lost from cheese was found in the brine. Results showed that Telem es cheeses produc ed from milk containi ng aXatoxin M 1 at a concentration close to either the m axim um acceptable level of 0.05 ·g/ l set by the European unio n (EU ) or at double this value, will contain the toxin at a level that is much low er or slightly higher , respectively, than the m ax im um acceptable level of 0.25 0 ·g of aXatoxin M 1 /kg cheese set by som e countries.