Determination of Aflatoxins and Zearalenone in Different Culture Media

Dante Javier Bueno and Guillermo Oliver

1. Introduction

Some molds produce desirable changes in food, but most are merely esthetically undesirable. There has also been an increasing awareness that certain metabolic products of some molds commonly found on foods and feed are dangerous to humans and animals. These toxin substances, mycotoxins, are secondary metabolites produced by different fungi, especially Aspergillus, Penicillium, Fusarium, and, to a lesser degree, Alternaria (1). The most important toxins for humans are aflatoxins, ochratoxin A, fumonisins, certain trichothecenes, and zearalenone (2).

Aflatoxins are fungal metabolites produced by different Aspergillus species: A. flavus, A. parasiticus, and A. nomius. The most commonly encountered aflatoxins are B1, B2, G1, G2, M1, and M2, but aflatoxin B1 (AFB1; Fig. 1) is the most frequently found in contaminated samples, and aflatoxins B2, G1, and G2 are generally not reported in the absence of AFB1 (3). The International Agency for Research on Cancer (IARC) considers that aflatoxins are carcinogenic (hepatocarcinogenic) to humans (group 1) and animals.

Zearalenone (ZEA; Fig. 2) is an estrogenic mycotoxin produced by several species of Fusarium (F. acuminatum, F. culmorum, F. equiseti, F. graminearum, F. verticilliodes, F. oxysporum, F. poae, F. rosum, F. solani, F. semitectum, and F. sporotrichioides) that primarily colonize different cereal grains (4). Several reports were noted on the occurrence of ZEA along with various combinations of group B trichothecenes, fumonisins, aflatoxins, and ochratoxins. In most cases, the levels of ZEA were considered to be low; however, the toxicological significance is not known (5). This toxin is not classifiable as to carcinogenicity in humans (group 3) by the IARC, but ZEA was implied in precocious sexual development in children in Puerto Rico and a breast enlargement in young boys in Italy (6).

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