The mash is the, you know, when you are making a whiskey. It's basically where you take, you're making a soup, almost, of grain, water, and yeast. There are different approaches that one can take to the mash. Some will use malted barley in their mash, not necessarily only for flavor, but also to help crack the starches. The first biotechnic patent in the United States was actually for enzymes for distilling.