Moulds and Ochratoxin A Occurrence in Cola Nitida Fresh Nuts after Treatment by Fungicide Epoxiconazole and Stored for Several Months in Various Containers

Abstract

The conservation of fresh kolanuts produced in Cote d’Ivoire and intended for the export, poses a veritable problem for the farmers. After 2 or 3 months of storage, the stock of kolanuts dramatically diminished occasioning high loss of economic resources. The aim of the present study was to find strategies for the best conservation for long period by investigation in appropriated nature of container, temperature of storage and in a possible fungicide adequate for kolanuts. Three (03) containers namely traditional made from the leaves of Thaumatococcus daniellii (Benn.) Benth., polyvinyl chloride (PVC) container and perforated cardboard have been studied. The temperatures of storage investigated were 26°C and 29°C while epoxiconazole is used as the fungicide. Fungi and Ochratoxin A (OTA) occurrence have been taken as bio-indicators of kolanuts healthy. Fungi were isolated by using Potato Dextrose Agar (PDA) and standard laboratory methods while OTA was extracted with a methanol/3% sodium hydrogen carbonate solution and purified using an immunoaffinity column prior to HPLC analysis with fluorescence detection. As results, the best temperature of storage could be 26°C and the container PVC had been found more efficient in fungi reduction in kolanuts when compared to traditional container made from leaves of Thaumatococcus daniellii (Benn.) Benth. In addition, OTA levels are stayed lows after 10 months of kolanuts storage. Moreover, the fungicide epoxiconazole was able to prevent Aspergillius flavus proliferation and retarded both Penicillium sp. contamination and OTA secretion in kolanuts until 6 months of storage. Taken together, the results suggested that a combination of the using of PVC container and fungicide epoxiconazole and 26°C as temperature of storage could improve significantly the conservation of fresh kolanuts for several months.