Hop To It! The Science Behind Beer

Barley, water, hops, and yeast. How do four simple ingredients come together to make thousands of different kinds of beer? The answer lies in the science of brewing. Brewing beer involves a series of complex biochemical reactions. For example, starches break down to form sugars. Sugars break down to form alcohol. 

Let’s learn about the biochemical reactions behind beer in more detail. 

Did you know?

Ultraviolet (UV) light causes a chemical reaction in hops. This reaction gives beer a skunk-like odour. Most beer is bottled in dark brown glass to prevent this from happening.

What is malting?

The first step in brewing is malting. This involves soaking the grain in water. Usually, this grain is barley, a source of starch. Soaking barley allows its starches to germinate (or sprout). This way, they become softer and easier to extract for the next step. 

Once the barley has germinated, it is dried out. This is an important step. The temperature used to dry the barley will determine the type of malt it will form. Barley dried at higher temperatures produces a dark malt. Barley dried at lower temperatures produces a light malt. Malt affects both the colour and the flavour of the beer.

What is mashing?

The next step is a process called mashing. Brewers add hot water to the malted barley. This activates temperature-dependent enzymes. Enzymes are proteins that exist in all organisms. They bind to other molecules and increase the speed of chemical reactions. Enzymes convert starches to sugars through a process called saccharification. 

Once the mashing process is complete, the malted barley can be filtered out of the mixture. The result is a sugary liquid called wort.

What are hops?

Next, the brewer adds hops to the wort. Hops are flower buds from the female hop vine. Within these buds are chemical compounds called resins. They give some beers their bitterness and aroma. In order to extract the bitter resins from the hops, the wort must be boiled. This way, the hops become soluble and dissolve into the wort. By playing around with the amount of hops, you can control just how bitter (or “hoppy”) the beer will be.

Did you know?

Before the invention of modern refrigeration, hops were used as a preservative in beer.

What is fermentation?

Finally, the brewer adds yeast. Yeast is a single-celled organism that feeds on sugar. It is added to the sweet, hoppy mixture. There, it rapidly breaks down sugars, releasing carbon dioxide and alcohol.

This process is called fermentation. It ends when the yeast has consumed almost all of the sugar. After fermentation, the yeast is collected and reused for the next batch of beer. 

Did you know?

Alcohol has a lower boiling point than water. Alcohol boils at about 78.2 to 78.4 °C, while water boils at 100 °C. To make non-alcoholic beer from regular beer, you simply have to boil off the alcohol.

How do different types of beer get their flavour?

The end product is a hoppy, carbonated, alcoholic drink called beer. The flavour and type of beer depends on the temperature, timing, and amount of each ingredient. For example, the main difference between the brewing process of ale and lager is the temperature at which fermentation takes place.

The most important ingredient, however, is yeast. It helps make sure the same brand of beer has a consistent flavour. Breweries that make the same beer over and over must use the same strain of yeast. Most breweries will happily give out their recipes. That is because without their specific strain of yeast, you can’t replicate their beer. In fact, breweries are extremely protective of their yeast strain. They often store a backup supply off-site in case their main supply gets contaminated. 

What if there is a mutation in the yeast - that is, a change in its DNA? This can create a strain of yeast so different from the original it would be like comparing two different breeds of dogs. Mutated yeast will produce a beer that tastes completely different from the original. It might even taste bad!

Beer might seem like a simple beverage that many adults like to drink. But now you have an idea of just how much science goes into it. Cheers to that!