60% of the rice grain in the polishing process). That desirable pocket of starch in the center of the grain is called the (, ). It usually takes two to three days to polish rice down to less than half its original size. The rice powder by-product of polishing is often used for making rice crackers, Japanese sweets (i.e. Dango), and other food stuffs. If the sake is made with rice with a higher percentage of its husk and the outer portion of the core milled off, then more rice will be required to make that particular sake, which will take longer to produce. Thus, sake made with rice that has been highly milled is usually more expensive than sake that has been made with less-polished rice. This does not always mean that sake made with highly milled rice is of better quality than sake made with rice milled less. Sake made with highly milled rice has a strong aroma and a light taste without miscellaneous taste. It maximizes the fruity flavor of ginjō. On the other hand, sake made with less milled rice but with attention to various factors tends to have a rich sweetness and flavor derived from rice. Rice polishing ratio, called () (see Glossary of sake terms) measures the degree of rice polishing. For example, a rice polishing ratio of 70% means that 70% of the original rice grain remains and 30% has been polished away. Water Water is involved in almost every major sake brewing process, from washing the rice to diluting the final product before bottling. The mineral content of the water can be important in the final product. Iron will bond with an amino acid produced by the to produce off flavors and a yellowish color. Manganese, when exposed to ultraviolet light, will also contribute to discoloration. Conversely, potassium, magnesium, and phosphoric acid serve as nutrients for yeast during fermentation and are considered desirable. The yeast will use those nutrients to work faster and multiply resulting in more sugar being converted into alcohol. While soft water will typically yield sweeter sake, hard water with a higher nutrient content is known for producing drier-style sake. The first region known for having great water was the Nada-Gogō in Hyōgo Prefecture. A particular water source called was found to produce high-quality sake and attracted many producers to the region. Today Hyōgo has the most sake brewers