Trace elements in bean-to-bar chocolates from Brazil and Ecuador.

Background: The high quality and unique flavor and aroma of bean-to-bar chocolates have resulted in an increase in the consumption of these products. Nevertheless, cocoa beans may present inorganic contaminants from environmental and anthropogenic sources which can contribute to contamination of the chocolates, despite the fewer processing steps and few ingredients used in bean-to-bar manufacturing process compared to the industrial one. Therefore, this study aimed to evaluate the content of trace elements (As, Cd, Co, Cu, Hg, Pb, Se) in bean-to-bar chocolates and traceable cocoa beans from Brazil and Ecuador.

Methods: Bean-to-bar chocolate samples were acquired in Brazil (n=65) and Ecuador (n=10), considering the main products available: white, milk, semisweet and dark chocolate. Cocoa samples from dedicated farms (n=23) were analyzed for trace elements and inorganic contaminants regulated by Brazil and European agencies. Samples were mineralized using acid digestion (nitric acid and hydrogen peroxide) in a closed microwave-assisted system. Quantification of trace elements was performed using Inductively coupled plasma mass spectroscopy (ICP-MS) and Inductively coupled plasma optical emission spectroscopy (ICP OES) in optimized conditions. The analytical control was performed with certified reference materials (ERM BD512 - Dark Chocolate, Tort-2 and Tort-3 - Lobster Hepatopancreas and SRM 1547 - Peach leaves) and recoveries ranged between 84% and 105% for all elements.

Results: The trace element levels in the bean-to-bar chocolates were (mg/kg): As (<0.022-0.023), Cd (<0.002-0.74), Cu (0.11-21.2), Co (<0.003-1.88), Hg (<0.010-<0.010), Pb (<0.007-0.22), and Se (<0.029-0.35). The exposure assessment from inorganic contaminants in chocolates revealed up to 93% of provisional tolerable monthly intake (PTMI) for Cd and 123% of tolerable upper intake level (UL) for Co for children. Inorganic contaminants were also analyzed in cocoa beans from dedicated farms and Cd and Pb levels were found above the thresholds established by Brazil health agency.

Conclusion: The results observed for both bean-to-bar chocolates and raw materials (cocoa beans from dedicated farms) indicated a need for monitoring these trace elements.