Kassei Seishu (active sparkling sake)

Kassei seishu (active sake) is a type of effervescent sake, also referred to as the sparkling type. Generally known as a cloudy sake (nigori), it is made by coarsely filtering the sake moromi (fermentation mash) and finishing it without filtering it completely. As a result, it contains fine yeast particles and gas, and a faint, continuing fermentation produces a natural sense of effervescence. Because kassei seishu undergoes secondary fermentation in the bottle during production, many examples have a high alcohol content, and care is needed when opening the bottle. There are also usu-nigori (lightly cloudy) types, which likewise use secondary fermentation in the bottle but are lower in alcohol and finished sweet, as well as a method in which carbon dioxide gas is added. These characteristics have drawn attention to it as a new way to enjoy sake. Kassei seishu also helps refresh the image of sake. Under the Liquor Tax Act it is classified as a brewed alcoholic beverage (jozoshu-rui), yet it retains its position as seishu (sake). In recent years this category has become especially popular, and a variety of flavors and styles are being tried.