Jōzo arukōru, arukōru tenka (aruten)
- Brewer’s alcohol; (process of) alcohol addition
Under the Japanese Liquor Tax Law, refined alcohol is one of the subsidiary ingredients whose use is permitted when making seishu. The total weight of alcohol and other subsidiary ingredients is limited to below 50% of the weight of the white rice used (including kome-koji). Furthermore, the standards approved by the Tax Agency restrict the amount of alcohol that maybe used by a given production facility to within the range of 280 litres of alcohol (calculated at 100% alcohol content) per 1000kg of white rice used in a year.
During World War Two there were shortages of rice for use as a raw material for sake making, and the use of alcohol was permitted in 1942. Commonly, alcohol is added to the moromi a day or two before pressing. This is called arukōru tenka (アルコール添加, alcohol addition), often abbreviated to aruten (アル添) . Adding alcohol makes the flavour lighter, raises the percentage of alcohol, and increases resistance to hi-ochi bacteria. Even in the early Edo Period (1603-1868), the technique was used to prevent hi-ochi, when it was known as hashira jochu (long “o”, long “u”, 柱焼酎).
The raw materials for brewer’s alcohol are starchy substances like maize or sweet potato (which are saccharified), or molasses. After fermentation, these undergo continuous distillation through a fractionating column to give 95% ethyl alcohol. It is common now for raw alcohol to be imported, then re-distilled and refined domestically before use.