Filamentous fungi producing ochratoxin a during cocoa processing in Cameroon

Ochratoxin A (OTA) is the main rnycotoxin 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 +/- 1.4 x 10(7) CFU g(-1) and black Aspergilli a maximum value of 1.42 +/- 2.2 x 10(7) CFU g(-1). A toxigenesis study showed that Aspergillus carbonarius was the main OTA-producing strain isolated. Its maximum production could reach 2.77 mu g 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). (C) 2007 Elsevier B.V. All rights reserved.