Kasu yodan (addition of sake lees as a fourth stage)

Kasu yodan is a technique in which sake lees (kasu) are added to the moromi (fermentation mash) after the three-stage mash additions (soe, naka, and tome) have been completed. Its purposes are to make effective use of ginjo lees, to remove the diacetyl off-odor, and to adjust flavor and aroma. Using kasu yodan can further bring out the flavor and aroma of the sake and help improve its quality. In sake brewing, kasu yodan plays an important role.