Aflatoxin B1 contamination in wheat grains from selected grains markets in Kano State, Nigeria

Abstract

Consumption of wheat grains and other whole-wheat products has grown in recent years in Nigeria due to the policies and empowerments by the government in Agriculture. These foods are considered more nutritious and have been associated with a reduced risk of some major chronic diseases such as diabetes. On the other hand, studies have found different groups of fungal toxins, called mycotoxins, contaminating these wheat products. Among these mycotoxins, are the aflatoxins, a group of genotoxic and carcinogenic compounds produced by Aspergillus flavus and Aspergillus parasiticus. This study aimed to determine the levels of aflatoxins B1 in samples of wheat grains intended for human consumption from some markets in Kano State, Nigeria. Composite samples of wheat marketed in Dawanau, Wudil and Chiromawa were obtained. Macroscopic and microscopic examinations of the fungal isolates led to the identification of the following genera; Aspergillus flavus 92%, Alternaria spp. 66%, Aspergillus niger 50%, Penicillium spp 50%, Mucor 50%, Trichoderma spp. 50%, Rhizoctonia spp. 50%, Aspergillus fumigatus 33%, Curvularia spp. 33%, Aspergillus terreus 25% and Fusarium spp. 25%. Aflatoxin B1 was also extracted and quantified using Enzyme Linked Immunosorbent Assay (ELISA). Out of the samples analyzed, 75% were positive for aflatoxin B1. Two samples (from Dawanau and Wudil) showed aflatoxin B1 levels (4.3 μg/kg) higher than the limit established by EU legislation (4μg/kg) but none of the samples exceeded the level set by Standard Organization of Nigeria (10 μg/kg).