Effect of traditional processing on aflatoxin levels in Ghanaian cereal-based beverages

Abstract

Traditional Ghanaian beverages, including Asaana (a sweet-malted maize drink) and Burkina (fermented milk and millet drink), are popular among consumers. It is important to note that these beverages are typically produced using cereals that may be susceptible to aflatoxin contamination. This study investigated the effect of key traditional unit operations on aflatoxin levels during laboratory‑simulated production of Asaana and Burkina from grains experimentally contaminated with a toxigenic Aspergillus flavus strain. Freshly harvested maize and pearl millet were sun‑dried, adjusted to 15% moisture, inoculated with A. flavus, and incubated at 30 °C for 28 days. Aflatoxin B₁ (AFB₁) and total aflatoxins (AFB₁, AFB₂, AFG₁, AFG₂) were measured by HPLC following immunoaffinity clean‑up in grains over time and at successive processing stages. In millet, AFB₁ increased from 0.45 to 100.08 µg/kg over 28 days; in maize, AFB₁ increased from non‑detectable to 137.96 µg/kg. Steeping contaminated millet for 8 hours in the production of the Burkina beverage reduced AFB₁ from 100.08 to 30.48 µg/kg (69.5% reduction; p < 0.05), and total aflatoxins by ≈ 67%. Subsequent steaming of millet granules (30–60 min) and addition of fermented milk produced only small, statistically non‑significant additional changes; the final Burkina beverage contained 29.76 µg/kg total aflatoxins, corresponding to an overall reduction of 70.3%. In the production of Asaana, steeping contaminated maize for 24 h reduced AFB₁ from 137.96 to 61.06 µg/kg (55.7% reduction; p < 0.05); 3 d germination further reduced AFB₁ to 51.84 µg/kg (62.4% total reduction). Boiling malt mash for up to 2 h achieved only ~11% additional reduction (p > 0.05), and caramelised sugar addition had no meaningful effect beyond dilution.The sieved wort (Asaana base) after 1 h boiling contained 38.36 µg/kg total aflatoxins (72.2% reduction from contaminated maize). Traditional processing therefore achieved substantial (~70%) but incomplete reduction of aflatoxins, and residual levels remained above typical regulatory limits for AFB₁ when starting contamination was high. Effective control of aflatoxin in Asaana  and Burkina must therefore prioritise prevention and reduction in raw grains (good agricultural and storage practices) and promote optimised cleaning and steeping, rather than relying on heat processing alone.