Yamahai (山廃) is one of the ways of making the “shubo (酒母, yeast starter)”, which starts the fermentation of sake. The name is short for “yama-oroshi haishi moto (山卸廃止酛)”, and some sake has “山廃” or “山廃仕込み” (yamahai-jikomi) written on the label.
A method without yama-oroshi
In the traditional method, “kimoto (生酛)”, the steamed rice, rice koji and water in a tub are ground into a paste with a tool called a “kai (櫂)” on the day after the ingredients are put in. This task is called “yama-oroshi (山卸し)”. It was heavy work done three times a day, with two or three people working on each tub.
Yamahai is a method that drops this yama-oroshi task and uses the power of the enzymes in the rice koji to dissolve the steamed rice. It was developed in 1909 at the national brewing research institute.
How it differs from kimoto and sokujo-moto
| Name | Lactic acid that protects against unwanted bacteria | Yama-oroshi |
|---|---|---|
| Kimoto (生酛) | Produced by lactic acid bacteria inside the yeast starter | Done |
| Yamahai (山廃) | Produced by lactic acid bacteria inside the yeast starter | Not done |
| Sokujo-moto (速醸酛) | Lactic acid for brewing is added | Not done |
Because kimoto and yamahai wait for lactic acid bacteria to grow, they take about twice as long as sokujo-moto. Today, most sake is made with sokujo-moto.