Kanzukuri (sake brewing during winter) (寒造り)
Kanzukuri is the name of a Japanese sake brewing technique and applies to those made in winter when the air temperature is low. It is also called kanjikomi. It is sometimes used in contrast to shikijozo (sake brewing in all seasons).
However, they improved the brewing method of kanshu at Itami, where sake brewing skill was most advanced at that time in 1667, and this kanzukuri was established.
The Tokugawa shogunate then tried to standardize sake brewing by banning brewing other than kanzukuri, and shikijozo started to decline, and kanzukuri became the main brewing method.
As kanzukuri became the main method, sake brewing became restricted to winter and farmers became sake brewers as an extra job only during the winter, and toji worker groups began to form in each district.
Shikijozo was revived in Showa period with the use of industrial techniques and ventilation systems, but unrefined sake and other processes require low temperatures to encourage effective yeast activity. For this reason brewers made use of naturally low temperatures in winter, and small and mid-sized sake brewers use kanzukuri brewing even today. The sake brewers who make it have a hard job, working from the early morning during winter.