Filtration (roka)

Filtration (roka, 濾過) is an important step in sake production in which lees (ori) are removed from the sake. Freshly pressed sake still contains sediment and appears cloudy. After a process called orihiki, in which this sediment is allowed to settle quietly, a filtration machine is used to remove fine particles and impurities. The purpose of filtration is to remove color and off-flavors, as well as to adjust the flavor and aroma of the sake and eliminate unpleasant odors. In some cases, activated charcoal is used to remove color. This step is essential for improving the final quality of the sake, and it may also be carried out during storage before bottling. Filtration gives sake a clear, transparent, and attractive appearance.