Grading of fermented and dried cocoa beans using fungal contamination, ergosterol index and ochratoxin A production
S Aroyeun, G Adegoke, J Varga, J Teren
feed, food, fuel, mycotoxin, quality
S Aroyeun, G Adegoke, J Varga, J Teren. Grading of fermented and dried cocoa beans using fungal contamination, ergosterol index and ochratoxin A production. The Internet Journal of Nutrition and Wellness. 2008 Volume 8 Number 1.
Sixty four samples of cocoa beans consisting of sixteen sub samples replicated in quadruplicates were collected from five warehouses from southwest Nigeria and examined for fungal loads, ergosterol and ochratoxin A The levels of all these variables obtained were further used as indices for cocoa grading into food quality grade, FoQ grade (erg <5mg/kg; OTA < 1µg/kg), feed quality grade, FеQ grade (erg = 5-10mg/kg; OTA > 1<3.12 µg/kg), Screen for mycotoxin SFM grade (erg = 10-20mg/kg; OTA > 3.12µg/kg and Fuel grade FuQ (erg > 20mg/kg; OTA > 6.12 µg/kg). Using these ergosterol indices, 18.75% of the cocoa beans examined fell in the FoQ, 18.75% in the FuQ grade while 31.25% fell on both the FeQ and the SFM respectively. In conclusion, the use of ergosterol can be used as a rapid index to grade fermented, dried cocoa beans meant for export.
Molds are common contaminants of agricultural commodities. Foods and feeds. Fungal development on alimentary substrates can lead to different detrimental effects: alteration of technological properties decrease of nutritive value and synthesis of mycotoxins (Pitt and Hocking
Cocoa beans, a produce of commerce of
Materials and Methods
Sixty four samples of cocoa beans consisting of sixteen sub samples replicated in quadruplicates were collected from five warehouses from southwest Nigeria.
Determination of fungal counts
Surface sterilized cocoa beans were plated on malt extract agar after serial dilution. Incubtion was at 28° 2OC for seven days. Thereafter, colonies growing on thee plate were counted using a colony counter.
Extraction of ochratoxin A and quantification
After 7days, isolates were grown in yeast extract sucrose broth containing 2% yeast extract, 15% sucrose). Incubation was done at 28° 2OC for 7 days. The culture broths were later extrcated using the method of Varga
Determination of ergosterol content in cocoa beans
Extraction, quantification of ergosterol was done using HPLC apparatus in accordance with Lamper
Results And Discusssion
In table 4.38, the higher the fungal counts, the higher the ergosterol values and in most cases the higher the ochratoxin A values. This finding was in agreement with previous reports on the direct relationship between ergosterol, fungal counts and mycotoxin production (Lamper
The results obtained in this study supported the usefulness of the quality grading system described by Scnurrer, (1995). Based upon ergosterol and OTA content of the samples, only 18.25% of the samples reached FOQ grade (<5mg/kg ergosterol), OTA of this class is <1ug/kg and 18.25% fell in the FUQ grade with the ergosterol of 5010mg/kg and OTA >1ug/kg. 31.25% fell in the category of Screen for mycotoxin (SFM) grade having ergosterol of 10-20mg/kg and OTA in the range of 1.68-2.31ug/kg while 31.25% also fell in the last grade Fuel quality grade (FuQ) with ergosterol > 20mg/kg and OTA
In conclusion, the use of ergosterol can be used as an indicator of good cocoa bean quality and to predict the possibility of ochratoxin A formation by mycotoxigenic fungi in cocoa beans. In conclusion, this index can be relevant as a rapid test for screening cocoa beans samples meant for export.