Toxigenic fungi associated with processed (green) coffee beans ( Coffea arabica L.)

Abstract

Processed (green) coffee beans from Coffea arabica in Brazil were assessed for the presence of Aspergillus and Penicillium species both before and after surface sterilisation, the aflatoxigenic and ochratoxigenic potential of the isolates and ochratoxin A levels. Contamination by Aspergillus and Penicillium species was found on 96% and 42%, respectively, of 45 samples from 11 localities. After disinfection with 1% sodium hypochlorite, the levels fell to 47% and 24%, respectively. One hundred and eighty isolates were identified to species level and comprised Aspergillus sections Circumdati (10 species), Flavi (3), Nigri (3), Versicolores (4), while two were teleomorphic species. Eight species of Penicillium were isolated. Within section Circumdati, 75% of the isolates produced ochratoxin A and all except Aspergillus elegans and Aspergillus insulicola have previously been reported to produce ochratoxin A. One-third of the 18 isolates of Aspergillus flavus produced aflatoxin B 1 and B 2. None of the isolates belonging to Aspergillus section Nigri or Penicillium produced ochratoxin A. Of the 40 bean samples analysed, 58% were infected with potentially ochratoxigenic fungi but only 22% of these were contaminated with ochratoxin A at levels that varied from 0.47 to 4.82 ng/g, with an average contamination level of 2.45 ng/g.