The process begins with large high-grade rice kernels which are milled or “polished” to remove the outer layers leaving only the core or “pearl’ of starch that is the center of each grain. The amount of material removed from each kernel determines the purity of the remaining rice grain and is one factor in assigning classification to the resulting Japanese Sake. Once the rice has been polished to the desired depth, it is soaked and steamed to prepare it for the two-step fermentation process.
In the first step, the Koji (a benign fungus) is introduced to the rice and water mixture. The Koji converts the complex starch of the polished kernel to simple sugars. In the second stage, Sake yeast or Shubo (Moto,) completes the fermentation process by converting the sugars into alcohol.
Finally, the liquid content of the mixture is pressed out and filtered before being pasteurized and bottled. Hiro Sake is pasteurized twice, keeping its flavors. The finished Japanese Sake contains approximately 15% alcohol.
Hiro Sake is made with an unusually high polished ratio versus the national Japanese average, providing a light and refreshing flavor.