Shubo mashing

The mixing of steamed ricekoji and water to begin the making of yeast starter is called shikomi (mashing) or moto-tate . The first moto-tate of a given brewing season is called moto hajime (酛始, “beginning moto”). The temperature immediately after mashing is called the mashing temperature (仕込温度, shikomi ondo), and is usually 6-8°C for the kimoto school. If this exceeds 10°C, there is a danger of the yeast propagating too early (haya-waki, 早湧き). If it is below 5°C, the steamed rice hardens, and the growth of nitrate reducing bacteria, lactic acid bacteria and saccharific enzyme action can be insufficient. This means that the composition of the mash is insufficient in relation to the number of days passed, and can lead to the same result as haya-waki (premature growth) .

The mashing temperature for sokujo is 16-20°C, or 22-28°C for the variant known as “high-temperature sokujo” (which can be made in a particularly short time) . The mashing temperature has a great influence on the progression of later stages. If it is too high, saccharification is accelerated, but runaway yeast growth also occurs. High temperature saccharification shubo aims to restrict unwanted microflora and encourage saccharification by mashing at 55-58°C.

Mashing temperature is generally decided by considering the sei-mai buai, rice quality, and how hard or soft the steamed rice is. It can be calculated using the temperature of the mizu-koji and steamed rice (after cooling) in the following formula.


Temperature of steamed rice =


(target mashing temperature – mizu-koji temperature) x 3.5 + mizu-koji temperature.


(This is known as the 3.5 multiplication method.)