Science, Bitches | Issue 13

Science, Bitches | Issue 13

The science of beer

As a student in Dunedin, beer is probably relevant to your interests. Not only is this beverage delicious and intoxicating, but the beer-making process, while being an art form, is also jam packed full of science!

Beer is made of four key ingredients: barley; hops; water; and yeast. Other ingredients can be added to create a specific style, such as oats (to create oatmeal stout) or peppercorns (to create saison ale), or just to experiment. But exciting extras aside, letís look at what these four main ingredients bring to the party.

Letís start with yeast. Yeast is actually added to the brew last, but its job in the brewing process is the most important. Yeast is a wee microbe that ferments our sugars into alcohol, creating carbon dioxide on the side. Yeast likes an anaerobic, or oxygen-free, environment to do this, and a batch of liquid brew is just the place to do it. (Bonus fact: thereís a brewery in the States called Rogue that used beard yeast instead of normal brewersí yeast to make a beer.)

The first ingredient thatís used in beer making is malted barley. There are lots of kinds of barley that can be used, alongside other grains, and which varieties you use will determine what kind of beer you make. But what do I mean by malted barley? Malting is a process where the grains are soaked, which stimulates germination. This is how the barley grain, the seed, would usually grow into a new plant. Though before the grains actually sprout, they are dried. This malting process gets the grains to produce some enzymes that will chop up the starches in the grain into sugars we can use. If you chew on a barley grain, itís not sweet at all, but after we heat the grains in hot (65-ish degrees) water, the starch in the grains are chopped into sugars, and are drawn out into the water. Once youíve strained the grains, the liquid left behind Ė the wort Ė tastes really sweet.

Once we have the wort, we can start the boil. This is where we boil the wort and we start to add our next ingredient: hops. Hops are a plant closely related to hemp and marijuana. Hops do two things in beer: they add bitterness; and they add flavour and aroma. Often, a variety of hops are used. Bittering hops are added first, and need to be boiled for a while to extract the acids from the hops. Towards the end of the boil, the flavouring and aroma hops are added. The oils in the hops contribute to beerís characteristic hoppy taste and smell. Hops in New Zealand are grown in Nelson, and we have several varieties that canít be found anywhere else in the world. Each variety of hops makes beer smell and taste a little different. Brewers spend lots of time trying out different hops to make different beers. IPAs, or India Pale Ales, and APAs (American IPAs) are the hoppiest of beers and the choice of hops dictates what they will taste like.

Once weíve completed the boil and the beer is back to room temperature, we add our yeast and leave it to ferment. This can take a few weeks. Then the beer is ready to bottle.

You may have noticed the types of beers described in this column arenít quite your average Speightís. So next time youíre grabbing a beer, try a craft beer. Regardless, remember whom you have to thank: Science, bitches!
This article first appeared in Issue 13, 2014.
Posted 2:07pm Sunday 25th May 2014 by Hannah Twigg.