Changes in the cadmium content of rice, sake and sake-cake during sake brewing

Abstract

We studied the effects of sake making processes (rice polishing, washing, steeping, steaming) and the activated carbon treatment of sake on cadmium (Cd) content. In the polishing and washing process, Cd content in rice tended to fall slightly, and it hardly changed in the other processes. In a small scale sake brewing test using distilled water and 300g polished rice, Cd content in the supernatant during moromi mash was almost constant at a low value. Also about 90 percent of rice originating Cd shifted to the sake cake. The same results as from the small brewing test were obtained during sake brewing using tap water and 100 kg polished rice. The sake with Cd added (about 50 μg/kg) was treated with 10-1000 mg/kg activated carbon for 1 week, but no effect of a notable adsorption of Cd was seen.