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Filamentous fungi producing ochratoxin a during cocoa processing in Cameroon

Mounjouenpou P., Gueule D., Fontana-Tachon A., Guyot B., Tondje P.R., Guiraud J.P.. 2008. International Journal of Food Microbiology, 121 (2) : p. 234-241.

DOI: 10.1016/j.ijfoodmicro.2007.11.017

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 ± 1.4 × 107 CFU g- 1 and black Aspergilli a maximum value of 1.42 ± 2.2 × 107 CFU g- 1. A toxigenesis study showed that Aspergillus carbonarius was the main OTA-producing strain isolated. Its maximum production could reach 2.77 ?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.

Mots-clés : ochratoxine; fève de cacao; aspergillus niger; aspergillus; technologie alimentaire; qualité; contamination biologique; fermentation; cameroun; aspergillus carbonarius

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