Washing the rice by hand
Another production process essential to the flavor of Dassai is washing and soaking the rice. To understand how important the washing process is, consider the mechanism of sake crafting. Unlike malt for beer, rice for sake does not contain the amylase necessary for converting starch to sugar. The starch must first be converted into glucose with the help of koji, a mold known technically as aspergillus oryzae. The glucose and yeast are then combined to initiate fermentation that converts sugars into alcohol.
To facilitate smooth conversion of starch into glucose, the rice is steamed to soften the starchy material. Here the water content of the steamed rice is critical. Rice with excess moisture causes the koji mold to attach to its surface. On the other hand, when moisture content is well controlled so rice is less saturated, the koji mold is able to permeate the rice grain. Inside the rice, koji mold grows steadily to develop rice malt, achieving ideal conditions for continuous fermentation until the sake artisan's requirements are met.
How is such an important rice-washing process performed? Following the polishing process, which can takes up to three to four days and nights, the rice undergoes a washing process in which water content is controlled in increments of 0.1%. The reason we are able to control the water content of the rice so precisely is because we hand-wash the rice. Such fine adjustment cannot be done by machines, which are subject to a 0.3 to 0.4% error margin. Any sake producer, when sake is crafted for a special blind-tasting competition, the rice is hand washed. We go a step further: we hand-wash all our rice for Dassai. No other producers do this for it requires a significant commitment of time and effort.
We wash around 5 tons of rice a day. With a machine, one operator can finish the task in a hour. Hand washing takes five to six of us working all day. Because washing by hand is labor intensive and time consuming, common sense would dictate the use of machines. On the other hand, every producer knows that hand washing is preferable to using a machine if you want to make quality sake. Yet no one dared to break away from the convenience of machines. We actually admit he would rather like to use a machine, but only if it can control the water content level in 0.1% increments. The purpose of washing by hand is not for the sake of tradition, but to control the level of water content of the rice.