An Assessment of Aflatoxin Contamination in Tiger Nut using HPLC and Aflatoxin Reduction with Citrus Juices

Abstract

Aflatoxins are metabolites that have been implicated to be directly responsible for several diseases. This present study assesses the aflatoxin contamination of tiger nut (Cyperus esculentus) collected randomly from the markets in the capital cities of Kano (Ka), Kaduna (Kd) and Gombe (Gm) States in Nigeria between December 2012 and March 2013. High performance liquid chromatography (HPLC) was used to determine the concentrations of aflatoxins (B1, B2, G1 and G2) in the samples (n = 90). The results indicated that all the tiger nut samples collected were contaminated. The concentration of the four aflatoxins in the samples collected from the three locations was in the order: AFB1 > AFB2 > AFG1> AFG2. The highest concentrations for the individual aflatoxins in the tiger nut samples were AFB1 (21.100 ± 0.100 µg/kg), AFB2 (0.910 ± 0.000 µg/kg), AFG1 (1.510 ± 0.150 µg/kg) and AFG2 (0.905 ± 0.000 µg/kg) for Ka; AFB1 (21.050 ± 0.050 µg/kg), AFB2 (2.105 ± 0.000 µg/kg), AFG1 (3.115 ± 0.000 µg/kg) and AFG2 (0.105 ± 0.000 µg/kg) for Kd; and AFB1 (11.110 ± 0.010 µg/kg), AFB2 (1.300 ± 0.010 µg/kg), AFG1 (1.685 ± 0.000 µg/kg) and AFG2 (0.600 ± 0.000) µg/kg for Gm. The result shows that 90% of the tiger nut was above the 10 μg/kg limit, while about 17% was beyond the alarm limit of 20 μg/kg aflatoxins set by United State Food Safety Regulations and the Codex Alimentarius. The treatment of the samples with varied concentration of orange extract showed significant reduction in the concentration of aflatoxin. Aflatoxin B1 in the tiger nut samples was reduced by 75% and 67% respectively when treated with 50% and 100% (v/v) orange juice extract; the orange juice (100% (v/v)) also reduced aflatoxin G2 by 75%. Rinsing with water serve better in the remediation of aflatoxins B2 and G1 than does the orange juice extract. The study infers that consumption of the nut with citrus juice or rinsing the nut with highly diluted citrus juice would significantly reduce aflatoxin contamination in tiger nut, since the nut is normally consumed raw.