Internal filtration (naibu roka)

Internal filtration (naibu roka) is one of the filtration methods used in sake production, carried out mainly to remove suspended matter from the liquid. A distinctive feature of this method is that a porous filter medium is used, and a cleansing effect is obtained when the sake is filtered. In general, as the liquid passes through the inside of the filter medium, fine suspended particles are captured, yielding clear sake. This technique is important for improving sake quality in particular, and it is an indispensable process in making highly clarified sake.