The science of beer

Date:8 October 2019 Author: Leila Stein Tags:, ,

Beer is such a staple in South Africa you could mistake it for one of our main food groups. But besides keeping it cold, how much do we know about this round-the-braai beverage? Find out how beer works and the do’s and don’ts to keep your beer drinkable.

How beer works

To make beer, barley, water, hops and yeast are combined in a specific process. Barley is left to sprout to create malt, this malt is turned into a liquid called wort. This is then fermented with  yeast in fermentation vessels, a process which can last between 18 and 28 days.

According to How it works, this is when the yeast converts the glucose in the wort into ethyl alcohol and carbon dioxide gas, making the beer alcoholic and bubbly.

Through diffusion, glucose (C6H12O6) from the wort enters the yeast. As each glucose molecule enters the yeast it is broken down in a process called glycolysis. The result of this is two, three-carbon sugars called pyruvates, and some ATP (adenosine triphosphate) which gives energy to the yeast which then multiplies. The pyruvates are then converted into carbon dioxide (CO2) and ethanol (CH3CH2OH).

The heat at which the fermentation vessel is maintained and how long it is left for are dictated by the kinds of beer being made. After the fermentation period, the yeast has settled at the bottom of the vessel and the beer is pumped out of the fermenter, filtered and put into another tank before bottling. Here the level of carbon dioxide is adjusted by putting into a bit more CO2.

The do’s and don’ts of beer

Now unless you’re an avid microbrewer, it is unlikely you’re planning on making your own beer. But according to SAB, there is still some responsibility on your end to keep the beers as fresh as possible.

Here are six do’s and don’ts courtesy of Anton Erasmus, a SAB Trade Brewer, to enjoy beer at its finest:

  • Do: Store in a cool, dark place

Storing your beer in a cool, dry place keeps it out of the way of sunlight. When light comes into contact with beer it causes a reaction that changes the physical structure of the hop compounds, transforming them into ones which contain sulphur.

  • Don’t: Let it expire

Much like bread, beer can become stale. The longer it’s kept in it’s cool, dark spot the more time it has to oxidise, making it taste a bit like cardboard.

  • Don’t: Drink warm beer

This is one that most seem to know without being told, but warm beer tastes awful. Store beers such as lagers at 4ºC and ales and stouts at a slightly higher temperature.

  • Do: Be gentle 

Beer can get agitated when handled too much. The constant shaking speeds up the staling process as oxygen gets released when it gets moved around.

  • Don’t: Freeze

Freezing beer is a huge no-no. When beer is frozen, carbon dioxide is lost, making the beer flat and altering the taste. Frozen beer often results in the cap popping off and the bottle rupturing, ending up with your freezer a mess and you without a beer. If you want to chill your beer a bit quicker, rather put it in an ice bucket to avoid a frozen explosion.

  • Do: Clean glasses 

A dirty glass is never a good idea, but it will especially hamper your beer drinking experience as the beer could be tainted with other flavours in the glass. A clean glass also boosts the foam head and stops the bubbles from sticking to the side of the glass.

Image: Unsplash


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