What is the main feature of the Yamahai (Shikomi) method?

The main feature of the Yamahai method is indeed the involvement of natural lactic bacteria. This traditional brewing technique utilizes spontaneous lactic acid fermentation, which occurs naturally when certain environmental conditions are met. The introduction of natural lactic bacteria helps in acidifying the mash, which not only enhances the flavor profile of the sake but also aids in stabilizing it against unwanted microbial growth.

This method is distinct from others in sake production, as it does not rely on the addition of cultured lactic acid, which can often be a part of more modern brewing methods. Instead, by encouraging the growth of natural bacteria, brewers can achieve unique flavors and aromas that are often described as rich and complex.

While other options reference advanced techniques, they do not encapsulate the defining characteristic of the Yamahai method. For example, high-pressure techniques and genetically modified yeast are elements found in different production methods that cater to particular styles or innovations in brewing but are not connected to the essence of the Yamahai process. Fermenting at low temperatures, while a common practice in sake production, is not specifically a hallmark of the Yamahai approach, which traditionally allows for warmer fermentation leading to distinct results.