- Sedimentation, fining
Sake contains saccharifying enzymes deriving from kome-koji. Due to heating and cooling during the pasteurization process, this can cause milky turbidity, reducing the clarity of the sake and sometimes settling as ori sediment. Because cloudiness after bottling reduces commercial value, a process encouraging the precipitation of the sediment (called ori-sage (おり下げ)) may be carried out as a precaution.
Ori sediment is white, but the ori-sage process uses active carbon to remove colour and adjust flavour and aroma, so the flocculating sediment made when ori clusters around the carbon particles is black.
Methods of ori-sage by physical means include the use of precipitation due to the combination of tannin and proteins, the coagulation of alginic acid when in an acidic environment, or by coagulation and sedimentation with silicon dioxide.
Enzyme ori-sage utilizes the decompositional effect of protease on the sedimentary material. It ruptures the secondary bond in the molecules of the protein which is the cause of the cloudiness, then coagulating and settling as sediment.