Water is involved in almost every major process of sake brewing, from washing the rice to dilution of 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 kōji 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.