Flourishing first are the nitrate-reducing microbes, which thrive in nutrient-poor conditions.
As mash warmers slowly raise the temperature, the amount of nutrients available increases, leading to an increase in lactic acid bacteria. As lactic acid bacteria become active, nitrate-reducing bacteria and wild yeast are destroyed.
Addition of yeast
After the lactic acidity has reached the point where normal microbes cannot survive in the tank, the acid itself becomes weaker. When the yeast is added, the alcohol it produces kills the lactic acid bacteria, leaving the tank almost sterile except for the presence of yeast.
The yeast alone increases quickly.
The growth rate and fermentation of the yeast peak.
The mash is swiftly cooled, stopping yeast activity, and is then rested. Kimoto mash has a low yeast death rate during the karashi period, which means that when it is used for moromi, yeast purity is at almost 100%.