Toxigenic Aspergillus Diversity and Mycotoxins in Organic Spanish Grape Berries

Grapes are frequently contaminated by Aspergillus section Nigri fungi and ochratoxin A (OTA), with A. niger also capable of producing substantial fumonisin B₂ (FB₂) levels. Emerging evidence suggests that aflatoxigenic fungi may eventually replace ochratoxigenic fungi in certain regions due to better adaptation to changes in climatic conditions. However, research on the toxigenic fungal community and mycotoxins in grapes from organic vineyards remains limited. Research on Spanish conventional grapes is also deficient, with most of the available literature being outdated. The present study investigates the diversity of toxigenic fungi and the presence of mycotoxins in organically cultivated grape berries in Spain, which are renowned for their significant oenological tradition. This study employed species-specific PCR protocols for fungal characterization and optimized methods for the analysis of OTA, FB₂, and aflatoxin B₁ (AFB₁) by UPLC-ESI-MS/MS. The most prevalent species present were Aspergillus flavus, A. niger, A. parasiticus, A. steynii, A. carbonarius, and A. westerdijkiae (67.1%, 43.5%, 20.0%, 14.1%, 14.1%, and 11.8% of the samples, respectively). OTA was detected only in 16 samples (19%), averaging 0.48 ng/g and peaking at 0.7 ng/g, which were lower than previously reported for conventional grapes. There was no FB₂ or AFB₁ detected. This study is pioneering in its exploration of the occurrence of toxigenic mycobiota, beyond Nigri fungi, and subsequent potential for other serious mycotoxins to contaminate Spain's organic grapes.