On Thursday, November 7, I attended an entertaining and intriguing Chemistry seminar presented by Tracy P. Hamilton. The speaker came from Arkansas to share his knowledge of home brewing beer; he has been brewing since 1997. During this presentation, he explained the history and story of beer, the differences between lagers, malts, etc., why beer has certain flavors, and the actual process of brewing beer.
There is no precise date known for when beer was first brewed, but it is believed that the domestic crops used for beer first appeared around 11,000 B.C. They were found in the middle east and used as a food source at first. Hops weren't first used until around 850 AD. Beer was actually discovered on accident by trial and error once the feeling of intoxication was experienced. Brewing even helped contribute to the literacy of people by providing opportunities for citizens to record and keep track of the amount of grain held in warehouses.
The basic process of brewing involves making sugar water and adding yeast; the sugar converts to alcohol and carbon dioxide. On a more specific level, first you need malted barley. Malting is the process of germinating seeds that produce enzymes which break down protein and starch. Then you dry the seeds again. The malted barley must then be gelatinized followed by mixing the grain and hot water to form "the mash". While making the mash, the enzymes within must be held at specific pH and temperature ranges depending on the type of beverage being made. Lautering comes after mashing, this involves rinsing the sugars from the mash (we want maltose, not sucrose). The sugar solution then becomes "wort" and is boiled to remove proteins. Once this is complete, yeast is added after the wort has cooled and aerated. The last step is fermentation; temperature is very important in this step, lagers are held at 50F and ale at 70F. And voila, beer!
Another interesting topic Dr. Hamilton went over was how beers have certain flavors:
H2S - rotten eggs
CO2 - gives a bite
acetaldehyde - green apple
diacetyl - butterscotch, buttery
lactic acid - sour
dimethyl sulfide - cooked corn (means infection is present)
Overall, it was really neat and definitely not your average chemistry seminar!