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Cadmium (Cd) concentrations in cacao often exceed food limits. Recently, it was shown that cacao bean fermentation enhances Cd solubility, opening potential for Cd mitigation in cacao products. This study was set-up to identify changes in Cd speciation during fermentation. X-Ray absorption spectroscopy (XAS) complemented with speciation calculations, were used on samples collected from high and low Cd farms, that were subjected to a fermentation-like incubation that reached high temperatures (>45 °C) and acidic pH (<5). Incubation decreased nib Cd concentration up to a factor 1.5 and changed Cd complexation in high Cd beans from sulphur to oxygen ligands, likely due to pH changes. In beans with lower Cd concentrations, Cd was complexed before and after incubation with oxygen-ligands. A combination of pH changes and/or phytate breakdown may explain the migration of Cd outward from the nib. XAS and speciation calculations proved complimentary techniques and indicated similar speciation changes during fermentation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The pathways through which cadmium (Cd) is taken up and loaded into cacao beans (nibs) are yet to be revealed. Previous work suggested that Cd loading into cacao nibs may occur via direct xylem uptake rather than phloem-mediated redistribution from the leaves. A stable isotope ( 108 Cd) pulse-chase experiment was set up to identify the pathways of Cd loading into cacao nibs. The topsoil beneath two mature cacao trees in the field was enriched in 108 Cd via surface irrigation with a spiked solution. The increase in 108 Cd isotopic abundance (IA) in the plant tissues was followed up for 548 days after spiking. The 108 Cd IA in the plant tissues increased from natural abundance (0.89 %) to 7.0 % (tree A) and 10.1 % (tree B) at equilibrium. The tracer was taken up in the plant tissues in the order immature leaves > mature leaves > nibs in both trees, while tracer uptake in flowers and cherelles was less consistent between the trees. Half of the equilibrium 108 Cd IA was reached in the nibs at 191 days after spiking, significantly later than corresponding values for mature (151 days) and immature leaves (117 days). Pod maturation from flower stage takes about 6 months with most Cd entering the nibs at the last stage of development. The rather slow rise in the 108 Cd IA in the nibs compared to the leaves hence suggests that Cd in cacao nibs likely originates from phloem-redistribution from the stem, branches or mature leaves and not from direct root-to-nib transport via the xylem., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Recent cadmium (Cd) regulation in chocolate threatens the sustainability of cacao production in Southwest America. Cadmium contamination in cacao beans has not been assessed at a country level. A nationwide survey was conducted in Ecuador to identify the spatial distribution of Cd in cacao beans, as well as soil and agronomic factors involved. Paired soil and plant samples (pods and leaves) were collected at 560 locations. Information on agronomic practices was obtained through a prepared questionnaire for farmers. Total soil Cd averaged 0.44 mg kg -1 which is typical for young and non-polluted soils. Mean Cd concentration in peeled beans was 0.90 mg kg -1 and 45% of samples exceeded the 0.60 mg kg -1 threshold. Bean Cd hotspots were identified in some areas in seven provinces. Multivariate regression analysis showed that bean Cd concentrations increased with increasing total soil Cd and with decreasing soil pH, oxalate-extractable manganese (Mn ox ) and organic carbon (OC) (R 2  = 0.65), suggesting that Cd solubility in soil mainly affects Cd uptake. Bean Cd concentration decreased a factor of 1.4 as the age of the orchard increased from 4 to 40 years. Bean Cd concentration was inconsistently affected by genotype (CCN-51 vs. Nacional), pruning or application of fertilizers. It is concluded that the relatively larger bean Cd concentrations in Ecuador are related to the high Cd uptake capacity of the plants combined with their cultivation on young soils, instead of Cd depleted weathered soils. Mitigation strategies should consider the application of amendments to modify such soil properties to lower soil Cd availability. There is scope for genetic mitigation strategy to reduce bean Cd, but this needs to be properly investigated., (Copyright © 2018 Elsevier B.V. All rights reserved.)