Assessement of mycotoxigenic fungi and their toxins in coffee (Coffea arabica L.) From major coffee growing areas of jimma zone, southwest ethiopia

Abstract

Coffee is the most important agricultural export commodity to fetch foreign currency. It needs to fulfill the quality standards of safety up to maximum tolerable level in order to get acceptance from international coffee markets. However, coffee is naturally associated with several mycoflora and some of them may produce Ochratoxin A unless careful handling measures are in place. Therefore, this research was initiated with the objectives of identifying mycotoxigenic fungi associated with coffee todetect and to quantify Ochratoxin A from coffee beans collected from the soil, wet and dry processing coffee mills. A total of 77 coffee samples were collected from Mana, Goma, Gera and Limu Kosa districts of Jimma zone, Oromia Regional State of Ethiopia. Malt Extract Agar (MEA) was used for isolation and identification of fungi associated with coffee using macro and microscopic characteristics. HPLC was used to detect and quantify Ochratoxin A from green coffee bean. Different fungal genera, including: Aspergillus, Fusarium, Penicilium and Rhizopus were found associated with coffee beans from different coffee processing methods having different altitudes. Accordingly, Aspergillus spp (84.74 %), Fusarium spp (8.75%), Penicillium spp (5.49%) and Rhizopus spp (1.02%) were recorded. The mean ochratoxin A (OTA) detected from different coffee samples were; 6.24µg/kg, 2.05µg/kg and 1.2µg/kg from soil, dry and wet processed samples, respectively. Mean ochratoxin A concentration level was the highest in coffee collected from soil (6.24µg/kg) while the quantity was relatively the least from wet processed coffee samples. Likewise, the highest fungal incidence was encountered in coffee beans collected from soil and the lowest fungal incidence was observed in wet processed coffee beans. The present study revealed that the degree of importance of mycotoxigenic fungi in Jimma zone. To manage the mycotoxigenic fungi and their mycotoxins, avoiding collecting coffee from soil, controlling insect pest infestations, avoiding mold formations, controlling moisture content of coffee are recommended to get high quality and market competitive coffee beans.