ABSTRACT
Emil Christian Hansen's discoveries revolutionized the brewing industry, as the vast majority of breweries around the world, especially those producing lager beers, adopted the practice of pure yeast cultures by the end of the nineteenth century. Since that time, there has been an explosive increase in our understanding of yeast genetics, yeast physiology, and molecular biology. This chapter, which focuses almost entirely on strain selection in bottom-fermenting strains of lager yeasts, explores the reasons behind the limited implementation of traditional genetics and many of the "new" genetic techniques in yeast-breeding programs. Lager yeasts are generally characterized by a number of traits which interfere with normal genetic analyses: homothallism, polyploidy, aneuploidy, poor sporulation, and low spore viability. The need for strain development in brewing must go hand in hand with developments in brewing technology if brewers are to maximize raw material utilization and plant productivity and performance.
