From the middle, through to the end of Muromachi Period, the innovative ideas introduced by the brewing technique of Nara's Shoryaku Temple (which produced "Nanto morohaku"), made important breakthroughs in the history of our country's sake brewing. But, no less important was the introduction of enormous vats (10 koku vat) for sake brewing.
Until then, even the largest brewing pots and earthenware held only 1 koku (180 liters) or 2 koku (360 liters). Therefore, to make large volumes of sake, breweries had to prepare more than a hundred of earthenware pots.
Casks were also made to replace the earthenware pots. However, they lacked the experience in cask making and many of the casks leaked. To correct the problem, the casks were made from willow, which expends when exposed to water.
Better still, with the introduction of planes (imported from China in the middle Muromachi Period), that allowed the surface of boards to be shaved into curves, vats, able to brew a large amount of sake at a time, were developed. As a result, mass production of sake began.
From around this time, the nation's "sake brewing map" was in the process of changes. "Morohaku", once a monopoly of "Nanto (current Nara prefecture)", became sold as "... morohaku" in many of the provinces. Amongst them, the "morohaku" brewed in Itami and Ikeda (northwestern city in current Osaka prefecture) was a head above the rest and became popular not only in Kyoto and Osaka, but also as far as Edo (current Tokyo prefecture).
"Itami morohaku" was hailed as the best. It is said that 50 thousand koku (9 million liters) of "Itami morohaku" was brewed in Genroku 15 (1702) - an incredible amount, considering the technology of that era.
At the time, sake was brewed only 5 times a year. Each sake, brewed in
different season, had its name and were called "Shinsyu", "Aisyu", "Kanmaezake", "Kanzake" and "Haruzake". "Shinsyu" was brewed around the autumn equinoctial week. "Aisyu" was brewed in the season between "Shinsyu" and "Kanmaezake". "Kanmaezake" was literally brewed just before winter. "Kanzake" was brewed in the depth of winter, and "Haruzake" was brewed in spring. Not surprisingly, it was hard to beat "Kanzake" for its quality and flavor.
Ever since the heart of sake brewing moved on to Itami, the technique of sake brewing advanced even further. In the triple shikomi of "Nanto morohaku", equal amounts of steamed rice, rice malt and water were added in each of the three stages.
However, in the triple shikomi of Itami, twice the amount of steamed rice, rice malt and water used in "Hatsuzoe (first shikomi)" was added during "Nakazoe (second shikomi)". Similarly, twice that of "Nakazoe" process was added during "Tomezoe (third shikomi)". The process was executed much the same way as the current shikomi method.
But, as a result of the amount of water, used during the process, being reduced, its flavor was sweet, and the consistency became thick and creamy.