Sumishu (charcoal odor)

Sumishuu (炭臭), or charcoal odor, is an off-odor transferred to sake from the activated charcoal used for filtration during brewing. It becomes especially noticeable when the activated charcoal has not been sufficiently refined, has been stored poorly, or has been used in too large an amount. Because charcoal odor upsets the balance of a sake's aroma, it is regarded as an off-odor to be avoided as far as possible. For this reason, selecting and managing the charcoal is very important in sake brewing.