Koubo mutenka (no added yeast)

Koubo mutenka (酵母無添加) refers to sake made without the artificial addition of cultivated yeast during fermentation, relying instead on yeasts that occur naturally in the brewery. This approach is mainly found in traditional production methods such as kimoto and yamahai, in which yeasts native to the brewery environment are taken in to carry out fermentation. Sake made without added yeast is characterized by a diverse range of flavors drawn out by natural microorganisms, resulting in a distinctive and complex taste. This style of brewing is closely tied to the local climate and environment as well as the skill of the brewery owner, allowing drinkers to enjoy the individual character of each brewery.