yamaoroshi (grinding the starter ingredients with paddles)

Yamaoroshi is one of the key steps in kimoto (traditional yeast-starter method) sake brewing, and refers to the handling of steamed rice as fermentation progresses. In this step, steamed rice piled up in a shallow wooden tub (hangiri) is mashed with a paddle called a kaburagai, which helps bring out the aroma and flavor. Yamaoroshi is carried out to mix evenly the substances needed for fermentation, such as yeast, and it has a major influence on the quality of the finished sake. It is regarded as an especially important task in the development of the kimoto starter.