07 Pasteurization | Aging | Bottling
After sedimentation and filtering, most sake undergoes pasteurization (hi-ire) at a temperature of 60°C-65°C before storing. The purpose of pasteurization is to sterilize the liquid and at the same time to render and enzymes inactive. If the action of enzymes is allowed to continue, it increases the sweetness through the action of diastatic enzymes and alters the aroma through the action of oxidizing enzymes. Many sake products are pasteurized again during bottling.
Aging & Bottling
The heating of sake during the pasteurization process alters the aroma and leaves it with an unrefined taste. For this reason, it is allowed to age for six months to one year. Many sake products are brewed between autumn and winter following the harvesting of the rice, allowed to age during spring and summer and then shipped the following autumn.
The ABV% of sake aged in tanks is 17%-20%, the same as at the mash filtration stage. As this level is too high for consumption with meals, brewers often add water to reduce the level to around 15% before bottling. They may also filter and pasteurize it again, if necessary.