Nickel and copper accumulate at low concentrations in cacao beans cotyledons and do not affect the health of chocolate consumers

Abstract

Aim of study: Nickel (Ni) and Copper (Cu) are essential metals for the growth and development of plants. In view of the above, the aim of this work was to quantify and correlate Ni and Cu concentrations in the leaf and the parts of the fruit [pod husk, pulp, tegument (seed coating) and cotyledons] of clonal cacao genotype PH 16. Area of study: Cacao genotypes were collected from adult plants grown on farms located in three different climatic regions of southern Bahia, Brazil. Material and methods: Plant material was collected in four plots of twenty farms, located under different edaphic and topographic conditions. They were subjected to chemical analysis and later to statistical analyses. Main results: There was high variability of Ni and Cu concentrations in all evaluated plant materials. Leaf, pulp, and tegument were the plant materials that accumulated more Ni. On the other hand, the greatest accumulation of Cu occurred in the tegument and in the pod husk, while in the cotyledons there was little accumulation of these metals. The concentrations of Ni were influenced by the three climatic regions, a fact not observed for Cu, except at the leaf level. There was interdependence between the accumulation of Ni in the leaves and in the different parts of the fruit, a fact not observed for Cu. Research highlights: Since Ni and Cu accumulated in low concentrations in the cacao beans cotyledons, raw material for the manufacture of chocolate and other food products, these metallic elements do not affect the consumers' health.