Natural Occurrence of Ochratoxigenic Aspergillus Species and Ochratoxin a in Moroccan Grapes

The occurrence of ochratoxin A (OTA) producing fungi in Moroccan grapes was studied for the first time. Hence, a three year survey was conducted to investigate the presence of black aspergilli and in vitro OTA production capacity in four vineyards between 2004 and 2006. Fungi isolated from grapes were analysed and only isolates belonging to the genera Aspergillus and Penicillium were evaluated. No Penicillium spp. was found while 360 strains of Aspergillus spp. that were isolated. The most abundant specie were member of Aspergillus niger aggregate (82.5%) whereas A. carbonarius isolates were recovered only occasionally and in small numbers (3.3%). All Aspergillus isolates (360) were tested for their ability to produce OTA in CYA medium. OTA was detected in all culture of A. carbonarius (12 isolates) and 42.8% of A. niger aggregate isolates. Samples (n=22) collected in 2006 were analysed for their OTA content. Most of samples contained OTA at levels varying between 0.08 and 4.00 µg/kg. These results showed that Moroccan grapes were contaminated with ochratoxigenic species which represent a risk of OTA. Moreover, A. niger aggregate play the main role in the potential OTA contamination of grapes in vineyards with Mediterranean climates.