Jesse Dekeyrel, Tinne Mast, Marie Tuerlinckx, and Erik Smolders from KU Leuven’s Division of Soil and Water Management, together with Eduardo Chavez from the Escuela Superior Politécnica del Litoral (ESPOL) in Ecuador, have published a new study in Food Chemistry showing that post-fermentation soaking of cacao beans can significantly reduce toxic metal content.
The researchers tested a “bean washing” step — soaking freshly fermented beans in water, decanting, and drying — to lower cadmium (Cd) and nickel (Ni) concentrations in cacao nibs. On average, washing reduced Cd by 17% and Ni by 27%, with some varieties and particle sizes showing much higher reductions (up to 43% for Cd and 127% for Ni in powders). Adding magnesium chloride (MgCl₂) to the wash solution further improved Cd removal by competing with Cd for phytate binding sites. The effect depended on cacao variety and processing stage, suggesting that both metal-binding chemistry and transport limitations govern removal efficiency.
This post-harvest approach could help cacao producers in regions with naturally high soil metal content meet strict EU food safety regulations — notably the upcoming Ni limits (July 2025) and existing Cd limits — without costly changes to cultivation practices. While more research is needed on product quality and economic feasibility, bean washing offers a practical, scalable mitigation strategy that could protect both public health and market access.
Full reference:
Dekeyrel, J., Mast, T., Tuerlinckx, M., Chavez, E., & Smolders, E. (2025). Soaking cacao beans in water after fermentation can reduce the concentrations of cadmium and nickel in cacao products. Food Chemistry, 493(Part 2), 145789. https://doi.org/10.1016/j.foodchem.2025.145789
Acknowledgements:
The authors thank Hacienda Victoria for supporting the first experiment with beans, materials, housing, and facilities, and Olam Food Ingredients in Guayaquil for supporting the second experiment with bean selection, fermentation, and drying infrastructure. Special thanks to Jose Manuel Garcia and Nestor for their technical assistance.
