Ochratoxin- and aflatoxin- producing fungi associated with green and roasted coffee samples consumed in Argentina

MAGNOLI C.; ASTORECA A.; PONSONE L.,; BARBERIS C.L.,; FERNÁNDEZ- JURI M.G; DALCERO A.M.

World Mycotoxin Journal

Wangenigen Academic Publishers

Año: 2008 vol. 1 p. 419 - 427

1875-0710

The aims of this work were to identify the Aspergillus sections Nigri and Flavi, and to evaluate the natural occurrence of ochratoxin A (OTA) and aflatoxins (AFs) in green and roasted coffee. Likewise, the capacity to produce these toxins by Aspergillus species was studied. Fifty samples of Colombian coffee beans (25 green and 25 roasted) were obtained from a processor plant located in the south of Córdoba province (Argentina). The surface-spread method was used for mycoflora determination using the media dichloran rose bengal chloramphenicol agar (DRBC) and dichloran 18% glycerol agar (DG18). Ochratoxin A and aflatoxins analysis were performed by HPLC. The predominant species isolated belonged to Aspergillus niger aggregate (55 and 60%), followed by A. fumigatus (43%) from green coffee samples in DRBC and DG18 medium, respectively. From roasted coffee samples, A. flavus was the most predominant mould, isolated in similar percentages from both media (28.6%); followed by Aspergillus niger aggregate isolated in 28 and 14% in DRBC and DG18, respectively. Mean colony counts ranged from 2x103 to 3.5x104 CFU/g. The highest counts were observed in roasted coffee from DRBC media (p<0.0001). All samples of coffee were OTA negative (<1 ng/g). Twenty- five percent of black aspergilli strains, were OTA producers. The total of A. flavus assayed strains produced AFB1 and 80% of the A. parasiticus strains were AFB1 and AFG1 producers. The high percent of A. flavus and A. parasiticus aflatoxins- producing strains suggest a potential risk for contamination in coffee with AFs.