Heavy metal accumulation in leaves and beans of cacao (Theobroma cacao L.) in major cacao growing regions in Peru

• Published in: The Science of the total environment Vol. 605-606; pp. 792 - 800
• Main Authors: Arévalo-Gardini, Enrique, Arévalo-Hernández, Cesar O., Baligar, Virupax C., He, Zhenli L.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-12-2017
• Subjects: Cacao beans; Cadmium; Food quality; Lead; Trace elements; Zinc; Lead; Cadmium; Trace elements; Food quality; Cacao beans; Zinc
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2017.06.122

Peru is one of the leading exporters of organic cacao beans in the world. However, the accumulation of heavy metals in cacao beans represents a problem for cocoa bean export and chocolate quality. The aim of this study was to investigate the distribution and accumulation of heavy metals in cacao leaves and cocoa beans in three major cacao growing regions of Peru. The study was conducted in cacao plantations of 10 to 15years old in three regions of Peru: North (Regions of Tumbes, Piura, Cajamarca, and Amazonas); Center (Regions of Huánuco and San Martin) and South (Junin and Cuzco). Samples of leaf and cacao beans were collected from 70 cacao plantations, and the nature of cacao clone or genotype sampled was recorded. The concentrations of heavy metals such as Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in leaves and beans were determined using atomic absorption spectrophotometer. Overall, concentrations of heavy metals were below the critical limits; however, the presence of high levels of Cd in cacao grown in Amazonas, Piura, and Tumbes regions is of primary concern. Plantations of cacao with different cacao clones show differences in Cd accumulation both in leaves and cocoa beans. Therefore, it is promising to screen low Cd accumulator cacao genotypes for safe production of cacao on lightly to moderately Cd contaminated soils. Also, synergism between Zn and Cd present both in plant and soil suggests that Zn has a direct effect on Cd accumulation in cacao.
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•From 2019, the European Community will begin to limit levels of cadmium for chocolate affecting the Cocoa economy of Peru•>60% of the cacao beans studied had Cd content bellow the critical level•Concentration of Cd, Cr, Cu, Mn, Ni and Zn in leaves were correlated with the accumulation in cocoa beans•The accumulation of heavy metal in leaves and beans of cacao, are different by genotypes composition in the plantations•<Cd and Pb accumulation in leaves and cacao beans were in plantations with more clones and with natives genotypes