Survey of Philippine coffee beans for the presence of ochratoxigenic fungi

Abstract

In 2012 to 2014, Philippine green coffee beans from Coffea arabica in Benguet and Ifugao; Coffea canephora var. Robusta in Abra, Cavite, and Ifugao; and Coffea liberica and Coffea excelsea from Cavite were collected and assessed for the distribution of fungi with the potential to produce ochratoxin A (OTA). The presence of fungal species was evaluated both before and after surface sterilization. There were remarkable ecological and varietal differences in the population of OTA-producing species from the five provinces. Aspergillus ochraceus, A. westerdijkiae, and Penicillium verruculosum were detected from Arabica in Benguet and Ifugao while Aspergillus carbonarius, Aspergillus niger, and Aspergillus japonicus were isolated in Excelsa, Liberica, and Robusta varieties from Abra, Cavite, and Davao. Contamination by Aspergillus and Penicillium species was found on 59 and 19 %, respectively, of the 57 samples from five provinces. After disinfection with 1% sodium hypochlorite, the levels of infection by Aspergillus and Penicillium fell to 40 and 17%, respectively. A total of 1184 fungal isolates were identified to species level comprising Aspergillus sections Circumdati (four species), Clavati (one), Flavi (one), Fumigati (one), Nigri (three), and Terrie (one). Within section Circumdati, 70% of A. ochraceus produced OTA as high as 16238 ng g(-1) while 40% of A. westerdijkiae produced maximum OTA of 36561 ng g(-1) in solid agar. Within section Nigri, 16.76% of A. niger produced OTA at the highest 18439 ng g(-1), 10% of A. japonicus at maximum level of 174 ng g(-1), and 21.21% of A. carbonarius yielded maximum OTA of 1900 ng g(-1). Of the 12 species of Penicillium isolated, P. verruculosum was ochratoxigenic, with a maximum OTA production of 12 ng g(-1).

Keywords: Aspergillus; Coffee; OTA; Ochratoxigenic fungi; Penicillium.