Lessons in Fermentation
HomeBrewDoc
December 27, 2015
Posted by Samuel R. Atcherson
I am no expert at the chemistry and biology of beer, but I know enough for making beer what it is. The main ingredients in beer are quite simply: Water, Barley, Hops, and Yeast.
The Main Ingredients of Beer
Water is the most self-explanatory. It is what gives beer its liquid-y, drinkable form. Water makes up 90-95% of beer by mass. Although virtually any clean water can be used, the mineral content (e.g., level of hardness/softness) and pH (e.g., alkalinity/ acidity) can create distinctive, regional flavors, or, used knowledgably, can make a good beer great. I keep hearing that water in the Central Arkansas area is great for brewing, right out of the tap (i.e., soft water). At times, a brewer might adjust the chemistry of their water with brewing salts and acids to make a particular beer more true to style and minimize flaws.
Barley is a seed of the barley plant. It looks quite similar to wheat plant. Barley actually has to be treated to prepare it for making beer, that is, turned into malted barley. In short, the barley seeds are soaked for a time to start the germination (sprout) process, but it is then halted prematurely and dried. The desired level of germination is such that the starches in the seed are converted to sugar but not permited to sprout fully. Malted barley can be kiln dried for different lengths of time and temperatures to yield different flavors for the various styles of beer. Malted barley is crushed and soaked (mashed) at specific temperatures to extract the sugars for brewing. Either brewers prepare the mashing of the grains by themselves, or they can be purchased pre-packaged as grains that have been processed into a liquid malt extract (LME) or dried (powder) malt extract (DME).
Hops are the cone-like flowers of a female, vine-like (bine) plant called Humulus Lupus. Inside hops are lupilin glands where there is a soft oil resin. Hops help to balance the sweetness of beer by imparting bitterness, and they can also be used to impart aroma. Another helpful attribute of hops is that they have anti-baterial properties that can stave off certain "bad bugs" that would cause spoilage. Historically speaking, pale ales shipped from England to India was treated with extra hops to survive the long shipping route, which gave birth of the style India Pale Ale that many have come to love. There are many different kinds of hops and they are grown all over the world. They are used in brewing as wet (fresh) hops, whole hops, and pelletized (dried and powered) hops. More recently, the hop resin has been extracted and converted to liquid form as hop shots.
Yeast are single-celled living organisms (a fungus) that are credited for the production of the alcohol in beer. Yeast will feed off of the sugars of malted barley (or any other fermentable sugar, like honey, fruit, etc.). When yeast feeds, the beer undergoes the process of fermentation. Sometimes quietly, sometimes violently. My friend, John the Beer Snob, describes what yeast does the best, "Yeast eats sugar, craps alcohol, and farts carbon dioxide." Alcohol (ethyl alcohol) and carbon dioxide (CO2) are but two of the byproducts during fermentation. There are many cultivated strains of yeast that can also impart distinct flavors to beer. Another thing to know about yeast is that they help to divide beer into two distinct types (not talking about beers style here): Lagers and Ales. Lagers are fermented at colder temperatures (32 to 55*F) with bottom-fermenting yeast, while ales are fermented at warmer temperatures (55 to 75*F) with top-fermenting yeasts. Yeast almost always performs best in temperature controlled conditions. Yeast can come in liquid or dried form.