摘要:In order to establish a method for toxicological evaluation regarding bio-availability of heavy metals in food, the chemical form of cadmium in rice was investigated. Polishing of the rice can remove only a little of cadmium. In aluron particles separated by the differece of specific gravity from powdered rice, cadmium was located in 3.5-fold higher concentration than other portions, but it was far lower than the degree of concentration of phosphorus, mainly in phytic acid, which is about 65 fold. Cadmium was effectively removed from polished rice grains by only dipping them in acidic medium, but not in neutral and a little in alkaline media. Protein and relatively small portion of phosphorus accompanied cadmium by acidic treatment. On the other hand, diluted sodium chloride solution could also elute cadmium out of rice grains along with phytate-phosphorus. Both effects, acid and salt, look like additive and more than 95% of cadmium was removed from rice grains by several hours of dipping in a mixture of 1% acetic acid and 5% sodium chloride solution. The mode of release of cadmium, protein, and phosphorus under various pH conditions and the subsequent gel filtration of released cadmium fraction reveal that cadmium in rice grains exist as an insoluble complex with phytic acid and protein, which will become soluble, presumably in an inorganic form, in an acidic medium and also become partly soluble under alkaline condition making partly in a high molecular protein-binding form.