Occurrence of Aflatoxin in Some Food Commodities Commonly Consumed in Nigeria

Aflatoxicosis is a public health problem in Nigeria like other tropical and sub-tropical regions of the world. Control of aflatoxin contamination requires thorough risk assessment, monitoring, quality control and empirical data. This study assayed total aflatoxin levels, identified and quantified four aflatoxin types in five food commodities commonly consumed in the six geopolitical zones of Nigeria. The food materials: Zea mays, Colocynthis citrullus, Capsicum frutescens, Irvingia gabonensis and Arachis hypogea were obtained from Watt market in Calabar urban. ELISA method was used for total aflatoxin, HPLC for aflatoxin types, AOAC for moisture. All (100%) the samples were contaminated with aflatoxin. Contamination was highest in Irvingia gabonensis (63.40 ± 1.79 µg/kg) and least in Zea mays (3.20 ± 0.12 µg/kg) (p < 0.05). Except for Irvingia gabonensis and Colocynthis citrullus, total aflatoxin was within safe intake level of the Nigerian regulatory authority (National Agency for Food and Drug Adminstration and Control {NAFDAC}). All four aflatoxin types occurred in Irvingia gabonensis, Capsicum frutescens and Colocynthis citrullus; none was detected in Arachis hypogea. AFB1 contamination was highest in Irvingia gabonensis (11.71±0.10 µg/kg) followed by Capsicum frutescens (1.21 ± 0.01 µg/kg); AFB2 ranged from 0.00 ± 0.00-2.43 ± 0.05 µg/kg, AFG1 0.00 ± 0.00-3.73 ± 0.04 µg/kg, and AFG2 0.00 ± 0.00-0.54 ± 0.01 µg/kg (p < 0.05). Only Irvingia gabonensis exceeded the limit of AFB1 specified by NAFDAC for human foods. Moisture content varied widely (3.23 ± 0.03%-10.37 ± 0.19%). The trend in the occurrence of aflatoxins in the food samples was directly proportional (r = 0.91) to their moisture contents. Food commodities sold in Calabar carry potential health hazard. Improved handling through food processing, preservation and storage can minimize aflatoxins in foodstuffs and ensure sustainable quality of food supply.