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
Frederick Brewing Company says that Frederick Brewing Company was the first brewery in the United States to make beer with hemp seeds. By June 1997 Frederick Brewing Company had back-orders of 10,000 cases for their Hempen Ale. The ale also caught the attention of the Bureau of Alcohol, Tobacco, Firearms and Explosives, the Food and Drug Administration, and the Drug Enforcement Administration who got involved because it is illegal to grow hemp in the United States. Hemp seeds, imported from China, were a key ingredient in Hempen Ale making up 10% to 30% of the beer by weight. Federal regulators were also concerned