Brewing much studied, the preservative nature of the soft resins is not yet fully understood, though it has been observed that unless stored at a cool temperature, the preservative nature will decrease. Brewing is the sole major commercial use of hops. Yeast is the microorganism that is responsible for fermentation in beer. Yeast metabolises the sugars extracted from grains, which produces alcohol and carbon dioxide, and thereby turns wort into beer. In addition to fermenting the beer, yeast influences the character and flavour. The dominant types of yeast used to make beer are "Saccharomyces cerevisiae", known as ale yeast, and "Saccharomyces
Valentin Blatz Brewing Company part of Pabst. The "Blatz" beer label currently is produced by the Miller Brewing Company of Milwaukee, under contract for Pabst Brewing Company. The Blatz Brewery Complex and Valentin Blatz Brewing Company Office Building in downtown Milwaukee are listed on the National Register of Historic Places. The brewing company's office building has been converted into condominiums. The former Blatz bottling facility is now the Campus Center Building for the Milwaukee School of Engineering. The office building has been converted into the school's Alumni Partnership Center. Two famous Blatz/Milwaukee beer marketing slogans were "Blatz—Milwaukee's Finest Beer" and "Blatz—Milwaukee's Favorite Premium Beer".