CADMIUM-BINDING CAPACITY OF COCOA AND ISOLATED TOTAL DIETARY FIBER UNDER PHYSIOLOGICAL PH CONDITIONS

Cadmium binding capacity of cocoa and isolated total dietary fibre (TD F) was investigated in vitro under simulated physiological pH conditio ns. The effect of Cd2+ retention on the bioavailability of essential e ndogenous minerals was also studied. The sample was mixed with buffere d Cd2+ solution and, after equilibration, the residue was separated fo r quantitative measurement of soluble Cd2+ in the supernatant. Cocoa e xhibited a high affinity for Cd2+ in solution. The amount of bound Cd2 + rose with increasing metal concentration and pH. TDF was the major f raction responsible for binding of Cd2+ by cocoa. Phytate was probably another important cause of the decrease of Cd2+ solubility. The addit ion of various concentrations of Cd2+ to cocoa and TDF was shown to af fect the solubility of endogenous minerals. When Cd2+ was bound by TDF there was a marked increase in the availability of endogenous Fe, Zn, Ca and Mg, specially at duodenal pH conditions.