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
G. Heileman Brewing Company Brewing Company declared bankruptcy in January 1991. The troubled firm sought salvation with an aggressive push into the malt liquor market. In a controversial move, company leadership developed a new brand of malt liquor to be named "Power Master". "Power Master" brand of malt liquor was brewed with an alcohol by volume of 7.4%, significantly higher than existing malt liquor brands. Protestors cited Heileman's distribution and advertising strategies as evidence that the company was targeting the high-alcohol beverage toward urban African-Americans, especially in Chicago, one of Heileman's core markets. Fr. Michael Pfleger took a leading role in opposing Power Master,