Determination of aflatoxins in by-products of industrial processing of cocoa beans

Abstract

This study has examined the occurrence of aflatoxins in 168 samples of different fractions obtained during the processing of cocoa in manufacturing plants (shell, nibs, mass, butter, cake and powder) using an optimised methodology for cocoa by-products. The method validation was based on selectivity, linearity, limit of detection and recovery. The method was shown to be adequate for use in quantifying the contamination of cocoa by aflatoxins B₁, B₂, G₁ and G₂. Furthermore, the method was easier to use than other methods available in the literature. For aflatoxin extraction from cocoa samples, a methanol–water solution was used, and then immunoaffinity columns were employed for clean-up before the determination by high-performance liquid chromatography. A survey demonstrated a widespread occurrence of aflatoxins in cocoa by-products, although in general the levels of aflatoxins present in the fractions from industrial processing of cocoa were low. A maximum aflatoxin contamination of 13.3 ng g⁻¹ was found in a nib sample. The lowest contamination levels were found in cocoa butter. Continued monitoring of aflatoxins in cocoa by-products is nevertheless necessary because these toxins have a high toxicity to humans and cocoa is widely consumed by children through cocoa-containing products, like candies.

Keywords:

• chocolate
• mycotoxin
• aflatoxin
• cocoa processing
• methodology
• validation

Acknowledgements

This research was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Proc. 05/60236-1 and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).