Chemistry of Beer – Overview of brewing

Beer is one of the oldest beverages known to man. We have tabulations, written documents of brewing to the 4th century BC. If we think about where it came from, it was probably an accident. All we needed was sugar and wild yeast. The yeast could convert the sugar into alcohol, which of course early man found enjoyable.

To make beer as a fermented process we know that it goes back to 4000 BC where we have written documents that actually explain the process. The beer that the ancients knew was probably not the same beer that we drink today. It had similar components. Most often it was barley, water, and yeast.

The beer Purity Laws

It wasn’t until the 700s AD that we got into using hops in beer. This became the main definition of beer in 1516 with beer purity laws. They have stated that beer should consist of malted barley, hops, yeast, and water.

  • The malted barley gives us the sugar that is required to create ethanol. It also provides amino acids and the lipids necessary for healthy yeast growth.
  • The hops add flavor components to balance the sugary taste of the malt. It also adds some essential oils that extend the life of beer.
  • The yeast does the heavy lifting. It is there to convert sugar into ethanol. Ethanol is important because it’s actually anti-bacterial. Beer will last longer in many cases than the grains might have.
  • Water is often overlooked. Water is essential to make sure that the yeast will process the carbohydrates well. This means that we have to have the right PH, calcium, and magnesium levels in our water.
Glasses of hops, grains and beer
Credit: https://www.thedailymeal.com/drink/beer-facts-questions-answered

The beer process

The process is not difficult, but there is a series of steps.

Malting is when we take the barley and turn it into malt. We are getting it wet so it will start to germinate. We don’t want it to germinate fully so therefore we stop it by kilning. Drying it out. With this, we can add some other flavor components.

We can heat it up a little bit to get caramelization. Or heat it up even more to get a nice bitter, chocolate-type taste component.

Once we have kilned it, we need to grind it. And then we can start the mashing process. The mashing process is going to add water so that we can start to hydrolyze our sugars. We bring the temperature up to the optimum range. Now we will get starch hydrolysis enzymes, alpha-amylase, and beta-amylase. If you are interested in learning more about basic malts check our Introduction to brewing malts- The basics.

At this point, we don’t want to boil it. It turns out if we get too hot we will deactivate those two enzymes and be left with a very sweet flavor beer. We let those two enzymes really convert much of the starches into our small fermentable sugars.

Brewery style mashing process in a large mash tun
Credit: https://www.samuelsmithsbrewery.co.uk/fruit-beers/

The beer boil and adding hops

We need to remove the wort, which will be our dissolved components, away from our grains. Then we take that wort and bring it to a boil. When we boil the wort we are doing a couple of things.

  • We are making sure that we are sterilizing the entire wort. This is important because when we introduce yeast we want our yeast doing the fermentation and not some wild yeast or bacteria.
  • We also add hops. There are several places when you can add hops. We do it at the boil to extract alpha and beta acids. There are also some other essential oils that will help stabilize the beer.
glass jar of pelletized hops
Credit: https://www.brewcabin.com/dry-hopping/

Pitching the yeast and fermentation

When we filter out the hops, we bring the wort down to a lower temperature. Yeast has an important role. It’s converting the sugars into ethanol. The process starts ad aerobic respiration, and it’s going to go to anaerobic respiration. It’s this anaerobic respiration that gets us to the ethanol that is often associated with beer.

Once the fermentation is done, we have something that really resembles beer. We are going to let that age. Sometimes just a few days, and other cases maybe months. With this, we are going to get different components of taste to either develop or to be inhibited.

After aging, we need to do a second fermentation because as we know, beer is carbonated. The second fermentation is focused less on the creation of ethanol and more on the creation of carbon dioxide. The carbon dioxide carbonates the beer and gives us the mouthfeel that we are used to.

Pouring a mug of beer from a beer tap
Credit: https://learn.kegerator.com/force-carbonating-beer/

Historically the carbon dioxide and ethanol were important for beer to stay stabile. The lack of oxygen and the ethanol were both very important in making beer last longer. Then we can package it, either bottles, cans or kegs.

This is the overall beer process. This is what we know as beer. Cheers.

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