Aflatoxin Contamination of Various Carbohydrate Rich Foods, Legumes, and Vegetables, and Implications of Targeted Processing Techniques

Amadi P.U.,Ifeanacho M.O.,Agomuo E.N.

doi:10.13189/ujc.2017.050401

Abstract

This study was carried out to assess the levels of the metabolites of Aspergillus flavus; aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), and aflatoxin G2 (AFG2) in various food samples. Corn (24.00 µg/kg), millet (4.13 µg/kg), and cassava (3.88 µg/kg) contained the highest AFB1, while AFB2, AFG1, and AFG2 occurred highest in corn and yam. After processing, cassava and yam recorded the highest percentage of AFB1 and AFB2 reduction respectively, while the decontamination of AFG1 was jointly most effective after wheat and millet processing, and AFG2 reduced most after wheat, cassava, and millet processing. The occurrence of AFB1 in the legumes, followed the order; beans > breadfruit > groundnut > melon > oil bean and for AFB2 and AFG2 levels, breadfruit > melon > oil beans > beans, while AFG1 occurred highest in breadfruit, groundnut and oil beans. Ugba (6.26 µg/kg), Ogiri (10 µg/kg), and beans flour (14.62 µg/kg) had the least total aflatoxin contents of the legumes evaluated. Egusi, beans and oil bean recorded over 80% AFB1 and AFG1 reduction, while processing of groundnut and breadfruit, and breadfruit and melon produced the highest percentage of AFB2 and AFG2 respectively. The result for the vegetables showed least contamination of AFB1 in nchuanwu and bitter leaf, while the occurrence of AFB2, AFG1, and AFG2 in nchuanwu and bitter leaf occurred below detection levels. Blanched nchuanwu and bitter leaves had 100% AFB1 reduction, while the percentage reductions of AFB2 in oha and curry leaves, AFG1 in oha, and AFG2 in pumpkin leaves were 100%. This study has shown the presence of aflatoxins in the foods beyond permissible limits, as well as the effectiveness of milling, fermentation and blanching in reducing aflatoxins from carbohydrate rich foods, proteins, and vegetables respectively.

Highlights

Aflatoxins can be described as toxins produced as secondary metabolites by some Aspergillus species after the invasion and colonization of agricultural products
The aflatoxin B1 content of yam in this study was lower than that reported by Arorowa et al, (2012) for yam chips, but the values recorded for wheat and cassava in this study were comparable to those shown by Arorowa et al, (2012)
The aflatoxin G1 and G2 contents of the raw and processed carbohydrates shown in Table 1 indicated that with the exception of corn and cassava, the application of the distinct processing methods were effective in the reduction of these aflatoxins

Summary

Introduction

Aflatoxins can be described as toxins produced as secondary metabolites by some Aspergillus species after the invasion and colonization of agricultural products. Guchi, (2015) reported that aflatoxins are regarded as one of the most challenging mycotoxins because the fungi are capable of producing the toxins both at the pre-harvest and post-harvest stages. The most important members of the aflatoxin group are aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), and aflatoxin G2 (AFG2) that structurally appear as coumarin derivatives containing a fused dihydrofurofuran moiety. The occurrence of these aflatoxins is seen in ratios, dependent on different matrices. Especially beyond the 20ppb permissible limits, in most cases leads to eventual rejection

Methods

Results

Conclusion