Proximate Composition, Fungal and Aflatoxin Contamination of Melon and Bush Mango Seeds Sold in Ibadan Markets

Abstract

Melon (Citrullus spp.) and bush mango (Irvingia gabonensis) seeds are widely used as food ingredients in Nigeria, yet their nutrient-rich composition may support fungal growth and aflatoxin contamination when post-harvest handling is inadequate. This study evaluated the proximate composition, associated fungi and aflatoxin profiles of seeds sold in Bodija, Iwo Road and Ojoo markets in Ibadan, Nigeria. Eighteen samples were obtained from three vendors per commodity in each market. Fungi were isolated by direct plating on potato dextrose agar and identified using internal transcribed spacer sequencing. Proximate composition was determined by standard analytical procedures, while aflatoxins were quantified using immunoaffinity clean-up and high-performance liquid chromatography with fluorescence detection. The identified fungi included Aspergillus flavus, A. niger, Penicillium oxalicum, Fusarium incarnatum and Rhizopus oryzae. The most frequently occurring fungi in melon seeds was P. oxalicum, whereas R. oryzae predominated in bush mango seeds. Melon seeds contained 24.76–29.04% crude protein and 44.33–49.33% crude fat, while bush mango seeds contained 8.05–9.00% crude protein and 51.92–54.15% crude fat. Aflatoxin B₁ was the predominant aflatoxin reported in both commodities (9.16 – 13.11 ppb in  melon and 8.97 – 10.22 ppb in bush mango). The recovery of storage-associated fungi together with measurable aflatoxins indicates the need for improved drying, transportation, storage and retail handling. Larger, seasonally representative studies with complete analytical quality-control data are required to establish exposure patterns and support regulatory interpretation.