Ochratoxin A (OTA) is a ubiquitous mycotoxin produced by some species of Aspergillus and Penicillium. It has been detected in a variety of foods such as cereals, coffee, grapes, cocoa, wine, and spices. Consumption of OTA has been linked to kidney and liver diseases. The aims of this study were to determine the effects of (1) water activity and temperature (2) oil content and grinding and (3) probiotic bacteria on fungal growth and OTA production by Aspergillus fresenii and A. sulphureus. In

more »

... first study, the two fungi were grown on ground Niger seeds with 0.82, 0.86, 0.90, 0.94 or 0.98 aw and incubated at 20, 30 or 37°C individually. The two species showed similar growth patterns on Niger seeds under all of the testing conditions. There was no fungal growth on ground Niger seeds with 0.82 aw and the optimal growth condition for the two species on ground Niger seeds was 0.94 aw at 30°C. However, the optimal conditions for OTA production by A. fresenii and A. sulphureus were different. The optimal conditions for A. fresenii to produce OTA on ground Niger seeds was 0.90-0.94 aw at 37°C; whereas, A. sulphureus produced OTA optimally with 0.90-0.94 aw at 30°C as well as 0.94-0.98 aw at 20°C. Overall, A. sulphureus produced higher levels of OTA than did A. fresenii. The highest concentration of OTA (643 μg/kg) produced by A. fresenii was detected on seed samples with 0.90 aw incubated at 37°C for 15 days, while the highest concentration of OTA (724 μg/kg) produced by A. sulphureus was detected on samples with 0.98 aw incubated at 20°C for 10 days.In the second study, growth and OTA production by the two fungi on ground Niger seeds with different oil content (10, 25 and 35%) and on whole Niger seeds at 30°C were compared. All seed samples were adjusted to 0.94 aw in this study. The two fungi grew most rapidly on ground seeds with [...]