The Biology of Home Brewing

In the spirit of the holidays, I’ve chosen to focus on, well, spirits.

But for those who like to make their drinks at home, beer is the best bet. Students of Georgetown Inc. recently awarded a Vital Vittles Traditions Scholarship to some of Georgetown’s own talented brewers in Brewleith. The process comes down to four simple ingredients: malting barley, hops, water and yeast.

Malt grain refers to grain that has been soaked in water until little sprouts begin to grow, and starches are composed of long carbon chains with some hydrogen and oxygen attached along the way. Sugar, on the other hand, is a similar organic compound, but its ringed structure makes it much sweeter than starch.

The next step in creating your homebrew is to gather your hops. Hops are actually the female flowers of the hop plant — and you thought brewing was just for men! Hops are actually a member of the hemp family, too, which is the plant basis of some clothing as well as marijuana. Hops contain oil that has a combination of alpha and beta acids, which are responsible for beer’s tangy, bitter taste. Depending on the kind of hops you choose and how long you boil them, your beer will have a different flavor. Hops high in alpha acids are known as bittering hops, whereas hops with more beta acids are known as aromatic hops.

Choose your hops carefully: They play a crucial role in protecting your beer through the brewing process. Alpha and beta acids have several antibacterial properties to protect beer from unwanted “guests” in the final product, and change its surface tension to make it easier to keep the brew at a higher temperature for a longer amount of time without losing as much to evaporation. Usually, brewers use hops that have been made into pellets, though some British brewers have moved to using pure oil.

Water might seem like a no-brainer, but it actually has huge effects on the final product. Different minerals and ions present in water interact with the other ingredients in different ways and are often critical for the fermentation of yeast and its interactions with other proteins and enzymes that give beer its flavor. Some of the most common ions found in a successful brew water are calcium, iron and fluoride.

To kick off the beer-brewing process, the malt grain is steeped, much like tea, around 150 degrees Fahrenheit. The enzymes in the grain must reach a certain temperature to be activated to break down remaining starches to sugar, but if the brew gets too hot, the enzymes will become denatured. Then, the hops are added to the mix. Unfermented beer is called “wort.” While this name sounds terribly unappealing, wort is critical for the final product: Boiling it breaks down starches into sugar, which helps flavor develop and happens to be yeast’s favorite food.

Once the wort has cooled, it’s finally time to add yeast. Yeast, a fungus and major player in bread-making as well, is a tiny single-cell organism that reproduces by budding. And when it buds, it produces liquid courage: alcohol.

Unlike most of the life forms we typically encounter, yeast gets its energy from anaerobic respiration. We need oxygen to carry out a series of chemical reactions where we obtain energy from the food we eat, but yeast does not; it can convert sugar into alcohol and other byproducts on its own. Different species of yeast produce different types of brews: Bottom-fermenting yeast kept at cooler temperatures produces lagers, whereas top-fermenting yeast will produce ales.

The majority of what we consider to be defining characteristics of beer is all thanks to a little single-cell fungus. As it turns out, yeast is an incredibly versatile little organism: Along with producing alcohol, it interacts with chemicals in the wort to flavor beer in different ways. It also gives off carbon dioxide, the same compound we exhale, which is why beer is nice and bubbly.

It takes four to five weeks to generate enough consumable alcohol through fermentation to have a successful brew, so if you’re looking for something to take the edge off Thanksgiving at home, you’re a little late to the party. But as you responsibly indulge this year, take a minute to toast those nifty little fungi and plants that put the beer in your — or a friend’s — hand.

Originally published on The Hoya.

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