Extract; gen- extract

Under Liquor Tax Law, the quantity of extract (ekisu bun) of sake is defined as the weight in grammes of non-volatile substances in 100ml of sake at 15°C, and is largely composed of glucose and other saccharides (tōrui). The extract content of the majority of sake in the market is in the field between three and six, with very dry kara-kuchi examples at less than three, and very sweet ama-kuchi sakes at more than six, also existing.

It is possible to calculate extract content directly by evaporating the sample and weighing the extract residue, but this direct method requires great skill and experience. Consequently, it is generally calculated using SMV (or specific gravity ) and alcohol content. The Method of Analysis prescribed by the National Tax Agency gives the following formula for calculating the extract content of a sample.


Extract content = (1443/(1443+SMV)-A)×260+0.21

(A is alcohol content converted to specific gravity (15/15°C).)


            Gen-extract (gen written with the character for original) is the sum of the extract content of the sake and the extract content prior to the conversion of glucose to alcohol. It functions as an index of how far the rice in the mash has dissolved. Given the same ratio for mashing water, a higher gen-extract value signifies a higher level of solubility in the mash. It is calculated with the following formula.


Gen-extract = extract content + level of alcohol (%) x 1.5894.