Tan-hakkō・tankō fuku-hakkō・heikō fuku-hakkō
- Simple fermentation; multiple sequential fermentation; multiple parallel fermentation
These are terms used to describe different patterns of fermentation or brewing.
Brewing requires two biochemical processes: the breakdown of carbohydrates into glucose (saccharification), and the conversion of this glucose into alcohol (fermentation).
Simple fermentation is the pattern in which raw materials rich in glucose are used, so fermentation can proceed without the necessity for saccharification. Winemaking using grape juice as the raw material is the obvious example.
In the case of multiple sequential fermentation, the starchy materials used are first saccharified to give glucose before fermentation can take place in a distinct stage. The prime example is beer, where the starch in barley is degraded by the saccharifying enzymes from malt, and sugary wort is then fermented. (As it happens, both kimoto-school shubo and high temperature saccharification shubo have a separate saccharification stage before fermentation so these may be said to belong to this pattern.)
Multiple parallel fermentation describes the pattern in which the saccharification of starchy material and alcoholic fermentation occur simultaneously, as in the case of seishu moromi. In this case, saccharification proceeds gradually, and the resulting glucose is also gradually consumed in fermentation, meaning that glucose levels are kept lower than in other patterns of fermentation. This reduces stress on yeast from high glucose concentrations, making high levels of alcohol production possible.
Seishu has the highest level of alcohol of any fermented (as opposed to distilled) beverage in the world. This is entirely due to the remarkable technique of multiple parallel fermentation by which it is produced.
The three Japanese terms for the various forms of fermentation would, if directly translated, be: simple (single) fermentation; independent multiple fermentation; and parallel multiple fermentation. This last has occurred in various English texts over the years simply as “parallel fermentation”, but there is also long precedent for “multiple parallel fermentation”. I find “simple fermentation”, “multiple sequential fermentation” and “multiple parallel fermentation” to be the most effective translations. The last two can be shortened to “sequential fermentation” and the already common “parallel fermentation” with little risk of confusion.