<P> Bourbon whiskey distillers must follow government standards for production . By law (27 C.F.R. 5), any "straight" bourbon must be: produced in the United States; made of a grain mix of at least 51% corn; distilled at no higher than 160 proof (80% ABV); free of any additives (except water to reduce proof for aging and bottling); aged in new, charred white oak barrels; entered into the aging barrels at no higher than 125 proof (62.5% ABV), aged for a minimum of 2 years, and bottled at no less than 80 proof (40% ABV). </P> <P> Jim Beam starts with water filtered naturally by the limestone shelf found in Central Kentucky . A strain of yeast used since the end of Prohibition is added to a tank with the grains to create what is known as "dona yeast", used later in the fermentation process . Hammer mills grind the mix of corn, rye and barley malt to break it down for easier cooking . The mix is then moved into a large mash cooker where water and set back are added . The "set back" is a portion of the old mash from the previous distillation--the key step of the sour mash process, ensuring consistency from batch to batch . </P> <P> From the cooker, the mash heads to the fermenter where it is cooled to 60--70 ° F and yeast is added again . The yeast is fed by the sugars in the mash, producing heat, carbon dioxide and alcohol . Called "distiller's beer" or "wash", the resulting liquid (after filtering to remove solids) looks, smells and tastes like (and essentially is) a form of beer . The wash is pumped into a column still where it is heated to over 200 ° F, causing the alcohol to turn to a vapor . As the vapor cools and falls it turns to a liquid called "low wine", which measures 125 proof or 62.5% alcohol . A second distillation in a pot still heats and condenses the liquid into "high wine", which reaches 135 proof (67.5% alcohol). </P> <P> The high wine is moved to new, charred American oak barrels, each of which hold about 53 gallons of liquid . A "bung" is used to seal the barrels before moving them to nearby hilltop rackhouses where they will age up to nine years . As the seasons change, natural weather variations expand and contract the barrel wood, allowing bourbon to seep into the barrel, and the caramelized sugars from the charred oak flavor and color the bourbon . A significant portion (known as the "angel's share") of the 53 gallons of bourbon escapes the barrel through evaporation, or stays trapped in the wood of the barrel . Jim Beam ages for at least four years, or twice as long as the government requires for a "straight" bourbon . At the end of the aging period the amber liquid is filtered, bottled, packaged and sent to one of many distributors around the world using the three - tier distribution system . </P>

How many types of jim beam are there