THE SCIENCE OF BEER BY KRIS KRUEGER 1

BREWING IS AN ART AND A SCIENCE INVOLVING BIOLOGY AND CHEMISTRY 2

MALTING Malting is the controlled germination of barley. Germination is the process by which plants, fungus and bacteria emerge from seeds and spores, and begin growth. After steeping barley in water it is allowed to grow. Natural enzymes transform the insides from complex to simple starches. This process is simple biology. 3

MASHING AND LAUTERING By heating up the mashed grains to degrees a couple enzymes are liquefied which reduces the starches to maltose and other simple sugars Lautering is when the mash is heated again to 170 degrees, drained of liquid, then washed with hot water. The liquid is collected and is the base of the fluid that will become beer, called the wort. 4

BOILING AND COOLING To get a less opaque and foamy beer, the proteins must be thoroughly removed. When heated, proteins will collect to make a gummy precipitate that is more easily removed from the wort in this state. Boiling is also used to extract flavor from ingredients such as hops. The longer the boiling period, the more bitter flavor from the hops will be present. Boiling for much longer results in the sugars caramelizing, adding another flavor. After the boiling stage is done, the leftover liquid is quickly cooled. This removes even more proteins and tannins from the wort 5

PITCHING THE YEAST When the wort is cooled, a good amount of yeast is added. This stage has several sub-stages: The lag phase is when oxygen is immediately absorbed by the yeast. Enzymes in the yeast help it take in glucose, other complex sugars, and other nutrients. Respiration occurs while oxygen is being absorbed; yeast reproduces itself using oxygen and other nutrients. Fermentation occurs after all oxygen is used. Simply put, yeast turns one molecule of glucose into 2 molecules of ethyl alcohol (which gets us drunk) and carbon dioxide (the bubbly). 6 LagRespirationFermentation

CLARIFYING AND CARBONATION Once all available sugars are used for fermentation, that stage is over, and the yeast becomes inactive. Storing in a cool and bacteria free environment allows the beer to stay mostly transparent. However, the beer is also flat. Carbon dioxide produced during fermentation is allowed to escape through gas vents. To get the beer bubbly, brewer inject the desired amount of carbon dioxide themselves. 7

BEER ON THE RISE? Beer is actually on the decline in America!!