Whisky Enzyme and Yeast
Enzyme convert starch in grain to sugar which is converted to alcohol by yeast in next step.
Almost all whisky use enzyme in Malt for mashing except for rice whisky by koji.
2-raw barley Malt
2-raw barley Malt has good balance of enzyme and starch to make Malt whisky.
6-raw barely Malt
6-raw barley Malt has good more enzyme than starch. It is used for grain whisky mash because it has enough enzyme to convert starch not only in Malt but also in other grains to sugar.
Rye malt is used rarely for rye malt whisky in USA.
Koji is compound of koji mold and base grain.
There are several different type koji by base grain (Rice, Barely, Sweet potato and Soy bean) and koji mold type (White, Black and Yellow)
Normally Rice-Yellow koji is used for sake, White koji(Several different grain) is used for Shochu. Black koji(Several different grain) was originally used for Awamori but it is also used for Shochu today.
Some rice whisky uses koji instead of malt. It doesn't contain
Yeast is essential to convert sugar to alcohol after malt enzyme converting starch to sugar.
Majority of Scotch distilleries think Yeast doesn't have influence of whisky flavor and taste today.
However American and Japanese distilleries have opposite idea.
There are hundreds whisky yeast but most popular is distillery yeast which was developed in 1950s.
It is very good fermentation capability with good flavor.
Many distilleries are using brewery yeast provided from Ale beer brewery together with distillery yeast.
It provides rich floral/fruity flavor (Ester).
Some distilleries are challenging other yeast like champagne, sake and etc.