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 Heileman that same year. Throughout the 1930s, the company continued to expand their facilities to accommodate increased production needs. There was a major upgrade in the mid 1930s following the creation of Special Export, Heileman's second house brew. Whereas Old Style Lager was only around 4% alcohol, Special Export was over 6%. There was a brief slowing in production during World War II, when the company was impacted by the rationing going on in the country. It was also during WWII, the company took a different approach to brewing and marketing. Heileman began producing several new labels, none of which