Anka (heating method for the yeast starter tank)

Anka (行火, also given as gyoka) is a temperature-control method used in sake brewing. A heat source such as an electric heater is placed beneath the shubo (yeast starter) tank to raise the temperature inside the tank directly. It replaces the traditional method that uses a warming barrel (dakitaru), and its defining feature is more efficient temperature control. The anka method promotes fermentation of the shubo, for which temperature control is critical, and has become an indispensable technique for producing sake of stable quality. In particular, maintaining an appropriate temperature during shubo fermentation has a major influence on the final flavor and aroma of the sake.