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Yoghurt from cow's milk artificially contaminated with aflatoxin M[sub 1] (AFM[sub 1]) at levels of 0.050 and 0.100 g l[sup –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°C for up to 4 weeks. Analysis of AFM[sub 1] in milk, yoghurt, strained yoghurt and yoghurt whey was carried out using immunoaffinity column extraction and liquid chromatography coupled with fluorometric detection. AFM[sub 1] 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 AFM[sub 1] 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, AFM[sub 1] 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, AFM[sub 1] was rather more stable in yoghurts with pH 4.6 than with pH 4.0. The percentage loss of the initial amount of AFM[sub 1] 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 AFM[sub 1] 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. [ABSTRACT FROM AUTHOR]

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[sub 1] (AFM[sub 1]) contamination by immunoaffinity column extraction and liquid chromatography was 297. In the first sampling, the incidence rates of AFM[sub 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[sup -1]. In the second sampling, the incidence rates of AFM[sub 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[sup -1]. The results suggest that the current regulatory status in Greece is effective. [ABSTRACT FROM AUTHOR]

Telemes cheeses were produced using milk that was artificially-contaminated with aflatoxin M at the levels of 0.050 and 0.100 μ g/l. The cheeses produced in the two cheese-making trials were allowed to ripen for 2 months and stored for an additional 4 months to simulate commercial production of Telemes cheese. Concentrations of aflatoxin M in whey, curd, brine, and the produced cheeses were determined at intervals by liquid chromatography and fluorometric detection coupled with immunoaffinity column extraction. Concentrations of aflatoxin M[sub 1] in the produced curds were found to be 3.9 and 4.4 times higher than those in milk, whereas concentrations in whey were lower than those in curd and milk. Aflatoxin M[sub 1] was present in cheese at higher concentrations at the beginning than at the end of the ripening/storage period, and it declined to concentrations 2.7 and 3.4 times higher than those initially present in milk by the end of the sixth month of storage. Concentrations of aflatoxin M[sub 1] in brine started low and increased by the end of the ripening/ storage period but only a portion of the amounts of aflatoxin M lost from cheese was found in the brine. Results showed that Telemes cheeses produced from milk containing aflatoxin M at a concentration close to either the maximum acceptable level of 0.05 μ g/l set by the European union (EU) or at double this value, will contain the toxin at a level that is much lower or slightly higher, respectively, than the maximum acceptable level of 0.250 μ g of aflatoxin M[sub 1]/kg cheese set by some countries. [ABSTRACT FROM AUTHOR]