When looking at what makes sake special, one thing that comes up often is koji mold. It is the heart of the sake-making process -- no beverage in the world uses koji in its production the way that sake does. Of all factors involved in sake brewing, the addition of koji exerts the most influence on the final product. As such, it is deserving of some more detailed attention.

For those that might need it, a quick review: Koji mold is propagated onto about 30 percent of the steamed rice used in sake production. The enzymes produced as this mold grows into the individual grains break down starch molecules into glucose. This is then fermented by the yeast cells.

It takes about two days to prepare the koji for use in a fermenting tank. Once added to the tank, it continues to trickle sugar slowly into the mash; the yeast cells then eat that sugar and give off alcohol and carbon dioxide. The starch-to-sugar conversion, and the fermentation of that sugar, take place simultaneously in the same tank. This makes sake unique; in other beverages the conversion to sugar occurs first, and fermentation later.