Microbiological quality of raw and roasted African palm weevil (Rhynchophorus phoenicis) consumed in the south eastern Nigeria

Abstract

The level of microbial contamination of African palm weevil (Rhynchophorus phoenicis) was carried out to assess the health implications of consumption of the larva in raw and roasted forms. Raw Rhynchophorus phoenicis larva collected from rotting palm at Mgbo, Oba in Idemili Local Government Area and roasted Rhynchophorus phoenicis purchased along Onitsha-Owerri expressway all in Anambra State, Nigeria were used for the study. Streak method was used in the assessment of the microbial load in the raw Rhynchophorus phoenicis whereby fluid from intestinal content was inoculated to Nutrient and MacConkey agar and incubated at 37^oC for 48 hours, while those on Sabaroud agar were incubated at room temperature for five days. The roasted ones were milled before plate count method was applied. In this method one tenth milliliter (0.1ml) of the 4th part of diluents produced after serial dilution to the concentration of 10-6 was aseptically inoculated into MacConkey agar (3 plates), Nutrient agar (3 plates) and Sabaroud agar (3 plates) respectively. The result showed three species of bacteria: Staphylococcus aureus, Escherichia coli and Salmonella spp. in the live APW and three species of bacteria: Bacillus subtilis, Pseudomonas aeruginosa and Proteus vulgaris as well as two species of fungi: Cladosporum spp. and Aspergillus flavus in the roasted Rhynchophorus . Total bacterial count in the roasted Rhynchophorus phoenicis was 1.72 x 10⁶ CFU/g while Total fungal count was 4.3 x10² CFU/g. Rhynchophorus phoenicis though reported to be highly nutritious in terms of amino acid profile and presence of unsaturated fatty acid can be a source of food poison if not properly handled in sanitary manner during collection, processing and post processing period.

Keywords: African palm weevil, Rhynchophorus phoenicis, Staphylococcus aureus, Escherichia coli, Salmonella spp., Bacillus subtilis, Pseudomonas aeruginosa, Proteus vulgaris, Cladosporum spp., Aspergillus flavus