Fungi and ochratoxin A detected in healthy grapes for wine production

Abstract

Aims: The mycoflora of healthy grapes (i.e. without visible symptoms of rot) for wine production in Portuguese winemaking regions was assessed and its potential for ochratoxin A (OTA) production evaluated. The OTA content of grapes was also determined. Methods and Results: A total of 386 fungal strains were isolated by plating methods. The most frequent genera found in grapes were non-ochratoxigenic species: Cladosporium (28%), Penicillium (24%), Botrytis (13%) and Aspergillus (9%). Two OTA-producing strains were isolated, belonging to the species Aspergillus carbonarius and Aspergillus ochraceus. OTA was detected in three of four grape samples, up to 116 ng lֿ¹. Conclusions: OTA is being produced in healthy berries by Aspergillus species, namely A. carbonarius, at levels below the maximum recommended limit of 2000 ng lֿ¹ in wine. Significance and Impact of the Study: The OTA concentration detected in healthy Portuguese grapes does not represent a risk to wine regarding the legal limit established.