Sparkling sake (発泡性の日本酒) is sake that contains carbon dioxide gas and forms bubbles when poured into a glass. It is also called “sparkling seishu (スパークリング清酒)”.
How the bubbles are made
There are two main ways the bubbles are made.
- Carbon dioxide gas produced by yeast during fermentation is trapped in the sake
- Carbon dioxide gas is blown into finished sake
Nigori-zake that has not been pasteurized (hiire, 火入れ) may also continue to ferment and produce carbon dioxide gas if it is kept at room temperature.
How the law treats it
A product made by fermenting rice, rice koji and water and then straining the result falls under the category “seishu (清酒)” under the Liquor Tax Act, even if it has bubbles. Adding carbon dioxide gas to finished sake does not change the category.
Note that the category “happoshu (発泡酒)” is for alcoholic drinks that use malt or barley as part of their ingredients. It is not sake.
“Awa sake”, a standard set by an industry group
The Awa Sake Association (一般社団法人awa酒協会), a general incorporated association, has set a standard called “awa sake (awa酒)”. The main conditions are as follows.
- Only rice, rice koji and water are used, and the rice is 100% rice grown in Japan
- The bubbles come only from carbon dioxide gas produced by fermentation during brewing. The secondary fermentation may take place either in the bottle or in a tank
- The sake looks clear
- The alcohol content is 10% or more, and the carbon dioxide gas pressure is 0.35 megapascals or more at 20°C
- The sake is pasteurized
Products that meet the standard in the association’s inspection are certified as awa sake.