Four-Seasons Brewing (四季醸造)

Four seasons brewing is the brewing of Japanese sake (rice wine) throughout the year and not just in the cold of winter. Also, techniques and production methods.

Year wide production runs counter to the approach to cold-weather production.

In Japan from time immemorial through until the early part of the Edo period, with the exception of mid-summer, sake (rice wine) was brewed year-round as follows:

Shin-shu (Sake Nouveau)
In August of the old lunar calendar (around July in the modern calendar), old rice from the previous year's harvest was brewed.

Ai-shu
Sake brewed in early Autumn. Although the season corresponds to the present-day end of August when the lingering summer heat is intense, there were such benefits as fermentation of lactic acid bacterium was easy because of that. It is said to have become very smelly.

Kanmae-sake
Kanmae-sake is brewed in late autumn.
Kan-shu
Kan-shu is sake that is brewed during winter. Later on, sake kept being made in winter.

Haru-zake
Haru-zake is made at the beginning of spring
Because the climate is comparatively warm, care needs to be taken with the steeping period of Japanese sake which becomes shorter day by day. Also, after the rice must cools it is gently worked etc and various techniques are used to ensure that fermentation is not too rapid.

However, the practice of fermentation of sake in each of the four seasons died out in the Edo period.
Because of the following reasons:

Edo bakufu (Japanese feudal government headed by a shogun) policies
The bakufu put controls on brewing sake in place from time to time for reasons such as: the rice market, food supply situation and political turmoil etc. That is, when there was a need to tighten-up, there was a clamp-down and with the exception of winter sake, brewing was prohibited. On the other hand, when there was an oversupply of rice, rules were relaxed and, based on the 'Katte Zukuri no Rei' (Liberal Brewing Decree) etc, restrictions on four-season brewing were lifted. Whilst this happened time and again, shin-shu, ai-shu, kanmae-sake and haru-zake ended up not being produced because they depended on unpredictable provision of a brewing permit.
The pursuit of quality Japanese sake
Brewing during winter time is trying; fermentation proceeds slowly but generally, it is possible to produce good quality sake. In time, with the emergence of competition regarding the quality of sake, the brewing of sake in seasons other than winter was not considered. Thus the reemergence of four-season brewing techniques which had ceased for a time was actually a result of industrial technology from the 1920s.