Assessment of Cooked Ready-To-Eat Fermented Cassava Product Marketed in Enugu State, Nigeria: Microbial Quality, Aflatoxin Occurrence, and Cyanide Levels

Abstract

Abstract

Cooked ready-to-eat fermented cassava products (akpu/fufu) are widely consumed in Nigeria because they are affordable and constitute an important source of dietary energy. However, contamination during processing, storage, transportation, and marketing may compromise their microbiological and chemical safety. This study assessed the microbial quality, aflatoxin occurrence, and cyanide levels of cooked ready-to-eat fermented cassava marketed in Enugu State, Nigeria. Samples were collected from Mayor Local Market, Enugu State, and analyzed using standard microbiological and chemical methods. The total aerobic mesophilic bacterial count was determined using standard culture techniques, while isolates were characterized by colony morphology, Gram staining, biochemical tests, and lactophenol cotton blue staining. The isolates were further identified by 16S rRNA and internal transcribed spacer (ITS) gene sequencing. Cyanide concentration was determined using the alkaline picrate spectrophotometric method, while aflatoxins were analyzed by affinity chromatography and high-performance liquid chromatography (HPLC). Molecular characterization identified the isolates as Lactiplantibacillus plantarum and Candida tropicalis. Hydrogen cyanide was detected in all the assayed samples, with the highest concentration observed in Sample A (56.12 mg/kg), followed by Sample D (56.08 mg/kg), Sample B (52.43 mg/kg), and Sample E (52.38 mg/kg), while the lowest concentration was recorded in Sample C (52.32 mg/kg). Aflatoxins B1, B2, G1, and G2 were detected at low concentrations, whereas aflatoxins M1 and M2 were not detected in any of the samples assessed. The total quantified aflatoxin concentrations were 4.35785 × 10⁻² µg/kg, 4.31180 × 10⁻² µg/kg, 4.40200 × 10⁻² µg/kg, 4.33810 × 10⁻² µg/kg, and 4.37010 × 10⁻² µg/kg for Samples A, B, C, D, and E, respectively. The total aerobic mesophilic bacterial count, aflatoxin concentrations, and cyanide levels did not differ significantly among the assessed cooked ready-to-eat fermented cassava samples (p > 0.05). The low level of aflatoxin contamination and the high cyanide levels present a potential public health concern. Therefore, improved processing practices, adequate fermentation, and proper heat treatment are recommended to reduce cyanide content and enhance the safety of ready-to-eat fermented cassava products.