Occurrence of mycotoxins and ergosterol in maize harvested over 5 years in Northern Italy

Maize samples collected from storage bins and feed mills in Northern Italy between 1995 and 1999 were surveyed for the occurrence of aflatoxin B-1 (AFB(1)), zearalenone (ZEA), deoxynivalenol ( DON) and fumonisin (FB1); further, ergosterol was analysed as a fungal growth marker. The incidence and mean content of AFB(1) were generally low; nevertheless, a remarkable contamination was found in two samples ( 109 and 158 mug kg(-1)), while five others exceeded 20 mug kg(-1). DON and ZEA mean levels were significantly higher in 1996 (2716 and 453 mug kg(-1)) with respect to the other years, when mean contents ranged from 7 to 30% and from 3 to 17%, respectively, expressed in per cent of 1996 contents. FB1 was present in all samples and was by far the most remarkable mycotoxin in Northern Italian maize, with the exception of samples from 1996. The average level was 3064 mug kg(-1), 69.6% of samples resulted over 1000 mug kg(-1) and 16.9% over 5000 mug kg(-1). Significant correlations were found between ergosterol and the major mycotoxin(s) in each year (FB1 in 1995 and 1997-99; ZEA + DON in 1996). Consequently, ergosterol seems to be a good index of the toxicological quality of maize. Climatic conditions influenced the growth of different fungal species. In 1996, the first 20 days of October were extremely rainy; these weather conditions delayed the harvest until the first week of November and favoured the growth of DON and ZEA producing fungi and the synthesis of mycotoxins. On the contrary, the temperate and dry climate of the other years supported the growth of FB1-producing fungi.