Storage Conditions, Proximate Composition, Fungal Load and Aflatoxin Contamination of Cassava Flour Sold in Local Markets of Jos Metropolis, Plateau State, Nigeria

Author

M. Ibrahim, H. M. Adamu, D. A. Ajiya, D. E. A. Boryo

Abstract

 Among the most widely consumed staples in Nigeria is Cassava (Manihot esculenta) flour, but poor drying and storage practices leave it vulnerable to colonisation by aflatoxigenic fungi. This study assessed the storage conditions, proximate composition, fungal load and aflatoxin (B1, B2, G1 and G2) content of cassava flour sold in five major markets (Terminus, Katako, Bukuru, Farin-gada and Chobe) within Jos metropolis, Plateau State, Nigeria. Five samples were collected and analysed for moisture, ash, fat, fibre, protein and carbohydrate content using standard AOAC procedures; fungal load was determined by serial dilution and culture on potato dextrose agar; and aflatoxins were quantified by thin-layer chromatography (TLC). Relative humidity (13.0–14.3%) and temperature (30.0–32.5 °C) recorded at the point of sale exceeded FAO/FDA-recommended storage thresholds for dried cassava products in all samples. Moisture content ranged from 10.15 to 17.10%, with 60% of samples above the 12% safe-storage threshold, while total fungal counts ranged from 7.67 × 10³ to 56.67 × 10³ CFU/g. Sixty percent of the samples were contaminated with aflatoxins B1, B2, G1 and G2, with total aflatoxin levels ranging from below the detection limit to 1.0082 ± 0.09 µg/kg (sample CK08). Correlation analysis revealed weak and statistically non-significant relationships (P > 0.05) between total aflatoxin level and relative humidity/temperature, moisture content, and fungal load, indicating that pre-storage handling and processing hygiene, rather than storage conditions alone, are the stronger determinants of contamination. All samples fell within the European Union (4 µg/kg), Codex Alimentarius/NAFDAC (10–20 µg/kg) and ISIRI (15 µg/kg) permissible limits, indicating no immediate acute health risk from the cassava flour sold within Jos metropolis, although routine monitoring remains advisable in view of the cumulative health effects of chronic low-dose aflatoxin exposure.

Keywords

Cassava flour; Aflatoxin; Fungal load; Thin-layer chromatography; Food safety; Jos metropolis, Nigeria

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References

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