Effect of traditional processing operations on aflatoxin levels in laboratory-contaminated Asaana and Burkina beverages

Abstract

Traditional Ghanaian beverages such as Asaana, a sweet malted-maize beverage, and Burkina, a fermented milk-millet beverage, are widely consumed but may contain aflatoxins when contaminated grains are used as raw materials. This study evaluated aflatoxin production in experimentally contaminated maize and pearl millet and assessed the effects of selected traditional processing operations on aflatoxin levels during laboratory-simulated production of Asaana and Burkina. We adjusted maize and millet to approximately 15% moisture, inoculated them with a toxigenic Aspergillus flavus isolate, and incubated them at 30 °C for 28 days. We measured aflatoxin B₁ (AFB₁) and total aflatoxins by high-performance liquid chromatography (HPLC) following immunoaffinity-column clean-up. Contaminated millet was processed into Burkina using 4- or 8-hour steeping, granulation, steaming, and addition of fermented milk. Contaminated maize was processed into Asaana using 24-hour steeping, germination, sun-drying, crushing, boiling, sieving, and addition of caramelized sugar. AFB₁ increased during incubation from 0.45 to 100.08 µg/kg in millet and from non-detectable levels to 137.96 µg/kg in maize by day 28. Eight-hour steeping reduced AFB₁ in millet from 100.08 to 30.48 µg/kg, representing a 69.5% reduction. Overall, Burkina processing reduced total aflatoxins by approximately 70% under the conditions tested. In maize, 24-hour steeping reduced AFB₁ from 137.96 to 61.06 µg/kg. Germination further reduced AFB₁ to 51.84 µg/kg in wet malt, while subsequent sun-drying reduced it to 39.23 µg/kg. The results indicate that cleaning, steeping, germination, and sun-drying were more effective than steaming or boiling in reducing aflatoxin levels under the laboratory conditions used. However, residual aflatoxins remained when contamination of the starting grains was high. Traditional processing should therefore not be considered sufficient as the sole aflatoxin-control strategy. Prevention of contamination through good agricultural and storage practices, careful raw-material selection, improved hygiene, and process control remains essential for safer Asaana and Burkina production.