Occurrence of ochratoxin A, fumonisin B₂ and black aspergilli in raisins from Western Greece regions in relation to environmental and geographical factors

Abstract

The presence of ochratoxin A (OTA), fumonisin B₂ (FB₂) and black aspergilli in raisins from Western Greece regions (Messinia, Corinthia, Achaia, Ilia and Zante Island) was investigated in relation to the different geographic and climatic conditions in the 2011 growing season. The biseriate species Aspergillus niger “aggregate” and A. carbonarius were mainly identified. The population of A. niger “aggregate” species occurred in all raisin samples at colony-forming units (CFU) concentrations significantly higher (mean 2.2 × 10⁵ CFU g⁻¹ homogenate) than those of A. carbonarius population (mean 4.9 × 10³ CFU g⁻¹ homogenate), which occurred in 80% of the raisin samples. OTA was found in 73% of the samples at levels ranging from 0.1 µg kg⁻¹ to 98.2 µg kg⁻¹, with the highest level occurring in a raisin sample from Ilia that also contained the highest level of A. carbonarius. The European Union legal limit for OTA was exceeded in 15% of the raisin samples. FB₂ was found in 29% of the raisin samples at levels ranging from 7.1 µg kg⁻¹ to 25.5 µg kg⁻¹, with 20% of the samples co-occurring with OTA. Principal-component analysis was applied to levels of mycotoxins, fungal contamination, geographical data and environmental conditions recorded in the harvesting (August) or drying (September) period. Principal-component analysis clearly indicated a good direct correlation of rainfall and relative humidity with OTA and A. carbonarius contamination. A lack of clustering was observed when A. niger and FB₂ contamination were considered. This is the first report on the co-occurrence of the mycotoxins OTA and FB₂ in dried vine fruits from Greece.

Keywords:

• fumonisins
• ochratoxin A
• black aspergilli
• dried vine fruits

Acknowledgements

This work was supported by EC KBBE-2007-222690-2 MYCORED, which also supported a short-term visit to Yiannis Sarigiannis. The valuable technical assistance of Roberto Schena and Vincenzo Achille is also acknowledged. Dr. Vassiliki Sfika and the Peripheral Center of Plant Protection and Quality Control of Achaia of the Ministry of Rural Development and Food (Patras, Greece) are also acknowledged for the provision of environmental conditions data.