Overview
This study measured mercury, arsenic, lead, cadmium, selenium, zinc, and aluminium in cocoa beans or cocoa-bean fractions from Cameroon, Ecuador, Nigeria, and Ghana. Lead and cadmium varied by origin, with Nigerian cocoa beans having the highest reported lead (Pb) mean and Ecuadorian cocoa beans having the highest reported cadmium (Cd) mean. The source is routeable for cocoa and chocolate ingredient evidence, while its country-of-origin scope should remain separate from any US-market chocolate benchmark pool.
Key numbers
Table 1 reports heavy metals in cocoa beans as mg/kg, with n=3 analytical replicates:
| Origin | tHg | tAs | Pb | Cd |
|---|---|---|---|---|
| Cameroon | <0.01 | <0.06 | 0.37 +/- 0.05 | 0.05 +/- 0.01 |
| Ecuador | <0.01 | <0.06 | 0.33 +/- 0.04 | 0.20 +/- 0.04 |
| Nigeria | <0.01 | <0.06 | 0.52 +/- 0.07 | 0.020 +/- 0.003 |
| Ghana | <0.01 | <0.06 | 0.32 +/- 0.04 | 0.017 +/- 0.003 |
The same table lists source comparison limits of 0.1 mg/kg for mercury, 1.0 mg/kg for arsenic, 1.0 mg/kg for lead, and 0.5 mg/kg for cadmium.
Table 2 reports trace elements in cocoa kernels and shells as mg/kg:
| Origin | Kernel Se | Kernel Zn | Kernel Al | Shell Se | Shell Zn | Shell Al |
|---|---|---|---|---|---|---|
| Cameroon | <0.1 | 50 +/- 5 | 9.2 +/- 0.9 | <0.1 | 60 +/- 6 | 4.6 +/- 0.5 |
| Ecuador | <0.1 | 58 +/- 6 | 12 +/- 1 | <0.1 | 190 +/- 20 | 9.1 +/- 0.9 |
| Nigeria | <0.1 | 49 +/- 5 | 16 +/- 2 | <0.1 | 61 +/- 6 | 9.8 +/- 0.9 |
| Ghana | <0.1 | 51 +/- 5 | 54 +/- 5 | <0.1 | 68 +/- 7 | 68 +/- 7 |
Methods (brief)
The authors sampled Forastero cocoa beans from four stated origins and selected a 200 g mixed sample for analysis. Mercury was analyzed according to ISO 6637-1984(E), and arsenic, lead, cadmium, selenium, zinc, and aluminium were analyzed according to AOAC 986.15. The paper reports origin-level means with replicate uncertainty but does not report individual bean-level values.
Implications
The paper contributes origin-stratified cocoa ingredient occurrence data for Pb, Cd, total arsenic (tAs), total mercury (tHg), aluminum (Al), Zn, and Se. For chocolate evidence use, the cocoa-origin basis and small number of origin lots should stay visible; the paper should not be treated as a finished-product chocolate survey.
Related evidence
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