Sake is undergoing a worldwide boom in popularity. The flavor profiles of sake have changed over time thanks to technological development and the ability to harness the power of microorganisms. A type of mold called koji plays a particularly key role in shaping the flavor profile of sake, as it helps convert the starch in rice into sugar for fermentation. Brewers had long known that different strains of koji produce different tastes, but now researchers have been able to identify the specific effects that come from genetic differences. This knowledge in turn is enabling the development of new types of koji through genetic modification to produce more desirable flavors in sake. In this episode, we'll take a closer look at research on koji and see how the power of biotechnology combined with the wisdom of experience is opening up new possibilities for a part of Japan's food culture.