Karashi (resting of polished rice)

Karashi (literally "seasoning" or "resting") is a step in sake production in which polished rice is stored for a set period after milling and allowed to cool to about room temperature. The purpose of this step is to even out the distribution of moisture within each rice grain and prevent the grains from cracking when they absorb water. Karashi is generally carried out between the milling of the rice and the start of brewing (the moromi mash preparation). Specifically, the polished rice is placed in a breathable container, and its temperature is lowered so that its moisture content can settle. For example, in the cold winter conditions of Niigata Prefecture, a period of about 20 to 25 days is considered suitable for karashi. There is also a step called "degarashi" (出枯らし), which means leaving the koji for about one day after dekoji (出麹, the point at which the koji is taken out) before using it in the brewing. During this time, the koji is spread out thinly to dry. There is also karashi of the shubo (yeast starter), which takes place between the dividing of the shubo and its use; this is usually suitable at about 5 to 7 days. Karashi is an essential step for maintaining the quality of the rice, and it improves the flavor and quality of the sake.