- Filtration smell
A collective name for various odours which can be transferred to seishu from the materials used when sake is filtered．They include kami-shu (long “u” for shu, smell), paper smell), caused when filtration paper is used, momen-shu (cotton smell), from cotton materials insufficiently washed, fukuro-ka from unhygienic saka-bukuro, and tanso-shu (charcoal smell) from active carbon. This last is a burnt smell, somewhat similar to varnish or paints. The following are thought to be the reasons for its occurrence.
- Large quantities of carbon are used.
- The carbon used was left for a long time after opening and adsorbed unwanted substances.
- The carbon was left in contact with the sake for a long time.
Carbon smell is relatively difficult to detect with the nose alone, but becomes radically more noticeable in the mouth, and has a considerable effect on taste. Usually, it has the effect of masking the pleasant aroma of the sake proper.