Heavy Metals, Particularly Nickel, Contained in Cacao Beans and Chocolate.

Abstract

The contents of nickel and other heavy metals in cacao beans and its processed products was studied. For the study, 26 samples of cacao beans, 14 of cacao mass (bitter chocolate), 10 of cacao butter, 14 of commercially available chocolate (black, 9; white, 5) and 4 of powdered cocoa were collected. (1) On the average, the content of nickel was about 5 ppm in both cacao beans and cacao mass, while only 0.03 ppm in cacao butter. The contents of iron and copper were also observed little differences between cacao beans (xBAR : 112.4 ppm Fe, 24.7 ppm Cu) and cacao mass (xBAR : 82.5 ppm Fe, 26.7 ppm Cu), while markedly low in cacao butter (xBAR : 0.30 ppm Fe, 0.04 ppm Cu). (2) Nickel was detected 1.09 ppm on average in the black type of the chocolate, while only 0.14 ppm or less in the white type. Powdered cocoa contained 12.7 ppm of nickel on average, much higher than the content in cacao mass. Such tendency was also observed in the cases of iron and copper: black type, white type of chocolate and powdered cocoa contained, on average, 24.4, 0.82 and 362.5 ppm of iron and 5.36, 0.16 and 43.9 ppm of copper, respectively. Meanwhile, lead and arsenic were not detected in all samples. (3) As reference samples, shea and Borneo nuts and coffee beans contained 0.58, 0.45 and 0.55 ppm of nickel, 85.4, 137.1 and 67.0 ppm of iron and 0.72, 10.8 and 13.3 ppm of copper on average.