Cd and Pb in cocoa beans: Occurrence and effects of chocolate processing

Abstract

The aim of this study was to quantify Cd and Pb levels in cocoa beans from three cocoa producing regions of the world, along with their derived products (liquor, cocoa powder and cocoa butter). The contaminants were determined by inductively coupled plasma optical emission spectrometry (ICP OES) and two sample preparation procedures were evaluated: microwave assisted acid digestion and dry ashing. The limits of detection and quantification for Cd and Pb were 0.5 and 1.5 μg kg􀀀 1 and 7.0 and 22 μg kg􀀀 1, respectively. The study examined 90 samples of cocoa beans and the concentration range found for Cd was <0.0015–1.598 mg kg􀀀 1 and for Pb was <0.022–2.528 mg kg􀀀 1. In 8% (Cd) and 66% (Pb) of the samples, levels detected were higher than the maximum allowed limits. Dry ashing decomposition method was shown to be adequate to the determination of Cd and Pb levels in cocoa beans and their derivatives, with satisfactory results for accuracy and precision. High levels of Pb and Cd were found in beans from Brazil and Ecuador, respectively. The derived products obtained in the process showed Cd levels between <0.0015 and 0.118 mg kg􀀀 1 and Pb between <0.022 and 0.136 mg kg􀀀 1. A tendency of the inorganic contaminant to remain in the non lipidic fractions of the beans (cocoa powder) was observed. The ingestion of chocolate produced from contaminated beans can contribute to consumer exposure to inorganic contaminants, exceeding Cd PTMI for children. The use of cocoa beans from different regions (blends) in the manufacture of cocoa products can be an alternative in reducing the levels of these contaminants in the final product intended for consumption.