Filamentous fungi producing ochratoxin a during cocoa processing in Cameroon
2008
Mounjouenpou, Pauline | Gueule, Dominique | Fontana-Tachon, Angélique | Guyot, Bernard | Tondje, Pierre Roger | Guiraud, Joseph-Pierre
Ochratoxin A (OTA) is the main mycotoxin occurring in cocoa. A study was conducted in Cameroon to assess how filamentous fungi and toxigenesis were affected by the type of cocoa post-harvest treatment (boxes or heaps). The filamentous fungi isolated were almost identical when fermentation was carried out in boxes or heaps, with the presence of abundant black Aspergillus filamentous fungi: A. niger and A. carbonarius. Filamentous fungi were more abundant at the end of the harvesting season. Factors affecting bean integrity (poor handling, deferred processing) resulted in a qualitative and quantitative increase in contamination, when the total number of filamentous fungi could reach a maximum value of 5.5±1.4x10⁷ CFU g-¹ and black Aspergilli a maximum value of 1.42±2.2x10⁷ CFU g-¹. A toxigenesis study showed that Aspergillus carbonarius was the main OTA-producing strain isolated. Its maximum production could reach 2.77 μg g-¹ on rice medium. Aspergillus niger strains did not always produce OTA and their toxigenesis was much lower. Fermented dried cocoa from poor quality pods was the most contaminated by OTA: up to 48 ng g-¹.
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