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The Science of Brewing Beer

The Science of Brewing Beer

Have you ever wondered how brewing beer actually works? From turning a bunch of grains into delicious, fizzy goodness!

We’ve broken down the key steps of the brewing process, for those who want to geek out about how it works 🤓 



1. The Mash

This process takes the long starch molecules from the grains and breaks them down into smaller, fermentable sugars (glucose molecules). They are broken down by enzymes that are found in the grain, which are most active between 52 and 67°C.

There are two main types of enzyme - alpha amylase and beta amylase. They work best at different temperatures. So, mashing your brew at different temps will affect your final brew. Lower temps produce highly fermentable sugars which makes a drier, crisp tasting brew.


2. The Boil

After all the sugars have been extracted, the liquid (also called the ‘Wort’, pronounced ‘Wert’) is boiled, usually between 60 and 90 minutes. This process sterilises your Wort, and it’s during this stage that the hops are added, giving your kitchen a hoppy beer smell!

At the beginning of the boil, the bittering/boiling hops are added. These hops, as per their name, determine how bitter the beer is. It takes a while to extract the bittering acids, hence the longer brew time. Towards the end of the boil the aroma/finishing hops are added. The oils in these hops give each beer it’s own unique aroma. As these are the most volatile, they evaporate more easily and so are left until the end to be added.


3. Cold Break 

The Wort then needs to be cooled down as soon as possible. There are a few reasons. First, it helps keep those aroma oils in the brew, so the final beer has a hoppy aroma. Secondly, the quicker the liquid cools, the quicker the yeast can be added and reduces the chances of any contamination. And finally, when the Wort is still warm (above ~26°C), oxygen can interfere with the alcohol by oxidation which can result in an off-smelling beer, which no one wants! 


4. The Fermentation

Now we get to the alcohol making. Fermentation is the process by which the yeast converts glucose into alcohol. The more sugars that are in the Wort, the higher the ABV (alcohol content). As well as producing alcohol, the process also produces carbon dioxide which escapes through the airlock and causes that satisfying bubbling sound!

The fermenter must not allow any air to enter, as this can cause contamination. The other consideration is oxygen. Oxygen helps initiate fermentation at the beginning, however if it’s introduced after primary fermentation it may cause the yeast to produce more of the unwanted by-products, affecting the final aroma and taste.

Temperature control is also important, and a constant temperature needs to be maintained for the yeast to work most efficiently.

5. Bottling

Most importantly with bottling is keeping the beer contamination and oxygen free. Of course, also to give it its fizz!

Additional sugar is added as ‘food’ for the yeast and carbon dioxide is produced, which carbonates the beer.


6. Drinking

Finally, the magical moment comes when it’s time to try the beer! With homebrew, storing the beer upright helps the sediment to settle at the bottom to give the beer a better clarity.

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