Microbial analysis and quantitative assessment of aflatoxins from edible dried insects (Palm Weevil, Cricket and Shea Tree Caterpillar) consumed in southwestern and southeastern regions of Nigeria

Abstract

Currently in Nigeria, a large number of edible insects are known, and they are globally consumed. The aim of this research was to investigate the microbial load and aflatoxin levels in palm weevil, cricket, and shea butter caterpillars. Six different dried edible insect samples were obtained from different States in the country, (5 palm weevils from Ibadan and Owerri State, 5 shea tree caterpillars from Owerri, 10 palm weevils from Ogun, and 10 crickets from Ibadan and Ondo state). All the samples were packaged in sterile zip lock bags, microbial load analysis was carried out using Standard Microbial Technique, and aflatoxin quantification was done using High-Performance Liquid Chromatography (HPLC). Statistical analysis was carried out using the Statistical Package for Social Sciences (SPSS) version. Microbial analysis of cricket from Ibadan and Ondo showed high counts of total aerobic bacterial load (104.0 ×107 cfu/g and 91.0 ×10 7 cfu/g respectively), the highest aflatoxin quantification of fungi present had values of (17.00 μg/kg and 12.00 μg/kg) in cricket from Ondo and Ibadan respectively. The aflatoxin level was above the permissible limits for ready-to-eat edible dried insects (AFB1; 2μg/kg, Total aflatoxins; 4 μg/kg). Microbial Identification of bacteria and fungi colonies isolated from the palm weevils, crickets, and shea tree caterpillar revealed 3 dominant species of bacteria (Staphylococcus aureus, Escherichia coli, and Proteus mirabilis), three mycotoxin-producing fungi were isolated which includes; Aspergillus niger, Aspergillus terreus, and Aspergillus flavus. The presence of E. coli signifies a potential risk to food safety. Also, the presence of Aspergillus flavus in most of the edible insect sample suggests a potential risk for aflatoxin production. The findings of this study indicate an urgent need for strict quality control measures to ensure the safety of edible insects consumed in Nigeria. Additionally, research into effective processing methods to reduce contamination is recommended.