Food and Nutritional Sciences

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Browsing Food and Nutritional Sciences by Subject "A. ochraceus"

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    Occurrence of Ochratoxin A in Green Coffee: In Relation to Processing Methods in Nmma Zone, Oromiya Region of Ethiopia
    (Addis Ababa University, 2014-07) Bekele, Ambi; Desse, Gulelat (PhD)
    Ochratoxin A (OTA) is one of the important mycotoxins that contaminate a wide range of food commodities. OTA contamination of coffee is a worldwide problem. Coffee is a major Ethiopian export commodity generating about 25% of Ethiopia's total export earnings. OTA is mainly produced in coffee by fungal species of Aspergillus ochraceus, Aspergillus carbonarius and Aspergillus westerdijkiae (section Circumdati) . This study aims to assess the levels of OTA in green coffee in relation to drying process in Jimma zone, Oromiya, Ethi opia. A total of 18 coffee samples were collected from three coffee producing weredas of Jimma zone. The samples were comprised of dry and wet processed. Fungi profile was evaluated by direct plating techniques. OTA levels were analyzed using HPLC technique after extraction and filtration using an immunoaffinity column. Results obtained revealed an overall percentage of fungal contamination between 76.67%-100% and 73%-93% in dry and wet processed coffee, respectively. There was no drying process method difference in composition of ochratoxigenic species in dry processed coffee in three sites. Coffee from dry processed samples had a fungal incidence of 29.63% Aspergillus jlavus, 40.74% Aspergillus niger, 30% Aspergillus ochraceus, 29.26% Penicillium species, 21.11 % Fussarium species and 29.26 Rhyzopus and other unidentified species. While those of wet processed had a fu ngal incidence of 30.74% Aspergillus jlavus, 42.59% Aspergillus niger, 29.26% Aspergillus ochraceus, 26.66% Penicillium species, 23.70% Fussarium species and 28.52% Rhyzopus and other unidentified species. There was no fungal diversity in types of drying process. Aspergillus niger was the predominant fungal infection in both process with 42.59% and 40.74% in wet and dry processed coffee respectively. The least fungal occurrence in both processed coffee was Fussarium species with 23.7% in wet and 21.11% in dry processed. From a total of 54 isolates (36 Aspergillus niger and 18 Aspe/gillus ochraceus), only 4 isolates (7 . 14%) were capable of producing ochratoxin A with the range of concentration of 2.04 t03.32Jl glkg. From the total of 18 samples analyzed, 44.44% were OTA contaminated with the contamination level ranged between 2.74Jlglkg and 6.46Jlglkg. OTA levels were mostly below the recommended standards by EU (5Jlglkg) . There was no difference in OTA contamination between wet and dry processing while the mean value is 2. 7 1~l g/kg and O.97~l glkg in dry and wet processed respectively. Keywords: Coffee arabica L, A. niger, A. ochraceus, Ochratoxin A, Drying method