Fungal Flora And Ochratoxin A- Producing Aspergillus In Green And Roasted Coffee In Argentina.

MAGNOLI, C.E; ASTORECA, A.L.; PONSONE, M.L; BARBERIS, C.L; FERNANDEZ, M.G.; DALCERO, A.M.

Villa Carlos Paz, Córdoba, Argentina

Congreso; Integration of mycotoxin and toxigenic fungi myco-globe Research for Food Safety in Global System; 2006

Mycoglobe

Like other crops, coffee cherries and beans are subjected to contamination and colonization by fungi during different phases of development, harvesting, preparation, transport and storage. Studies on the mycoflora of coffee cherries and beans in the world have shown that Aspergillus, Penicillium and Fusarium are the main toxigenic fungal genera. The Argentinean adult population consumes coffee frequently, which is imported from Brazil and Colombia; and there are not information of the natural occurrence of OTA and ochratoxin producing fungi in this substrate. The objectives of the present study were to isolate and identify the Aspergillus and Penicillium fungal populations associated with green and roasted coffee, to evaluate the toxigenic potential of the identified isolates with regard to aflatoxin and ochratoxin production, and the natural incidence of OTA in the coffee samples. Fifty Colombian coffee samples (Coffea arabica) (25 roasted and 25 green) were collected from a processor plants located in the south of Córdoba, Argentina. Isolation and quantitative enumeration of fungal propagules were done on Dichloran Rose Bengal Chloramphenicol Agar (DRBC) and Dichloran 18% Glicerol Agar (DG18) using the surface-spread method. Taxonomic identification of the Aspergillus and Penicillium genera was made according to Pitt and Hocking (1997). The extraction and cleanup of OTA on roasted and green coffee was made using immunoaffinity column (VICAM) and detection by HPLC. The ochratoxigenic profile was studied in all identified strains belonging to section Nigri (Téren et al., 1996). Aflatoxins (AFBs) production were tested in all identified strains belonging to section Flavi (Geisen, 1996). Mycological survey of the 50 coffee samples indicated the presence of seven genera of filamentous fungi. The most frequent genus was Aspergillus spp., isolated in 86% and 71% in DRBC and DG18 from green coffee samples, respectively. Three common food species of Penicillium genus were identified: P. citrinum, P. crustosum and P. minioluteum in percentage ranging from 14% and 28%. From green coffee samples, A. niger and A. awamori were the most frequent species. From roasted coffee samples, A. flavus was the most predominant mould. All samples of coffee were OTA negative (<1ng/g). From 100 black Aspergilli strains, 25% were OTA producers. Aspergillus awamori was the species with the highest percentage of OTA-producing isolates (33%), while 20 percent of A. niger were OTA producers with levels ranging from 2 to 16 ng/mL. One hundred percent of A. flavus strains produced AFB1 with levels of 9.5 to 17.5 ng/ml. Regarding A. parasiticus, 80% were AFB1and AFG1 producers, with levels ranged from 11.5 to 48 ng/mL and 6 to 28 ng/mL, respectively. The incidence of toxigenics species of Aspergillus sections Flavi and Nigri indicate a possible human exposure to OTA and AFBs in Argentina through the ingestion of coffee.