Soaking cacao beans in water after fermentation can reduce the concentrations of cadmium and nickel in cacao products.

The European limits on cadmium (Cd) and nickel (Ni) in cacao products sparked interest in lowering metal concentrations in beans. This study evaluates the potential of soaking freshly fermented beans in water, decanting, and drying. This "bean washing" reduced nib concentrations by factors of 1.17 ± 0.07 for Cd (mean ± 95 % confidence interval) and 1.27 ± 0.11 for Ni at a pilot scale. Water temperature and replenishment had no effect, but the success of washing depended on the cacao variety. Reduction factors up to 1.43 (Cd) and 2.27 (Ni) were reached for powdered beans, suggesting that transport limitations impede metal migration to water. Adding salts to the wash solution further enhanced the Cd reduction factor to 2.47 and was more efficient with MgClthan with CaCl, suggesting Mg:Cdcompetition for phytate. These findings show the potential of bean washing, awaiting further product quality and economic feasibility tests.