Beer: A Science Project

 

Chemical-science

I had the pleasure of having some great science teachers when I was young. I know others that did not. I have heard science described as “boring”, “hard”, and “a waste of time”. Currently the US is ranked 24th in Science worldwide, and it is not hard to see why. We need to make science fun again. Science, meet beer. Beer, meet science.

The Process

For those of you who have no idea how beer is made, I will give you a crash course. Beer is a byproduct of fermentation, which was discovered by accident thousands of years ago. Fermentation happens when yeast, which is a single celled fungus, eats sugar. The yeast eats the sugar (through a process called anaerobic respiration), and as a byproduct of that metabolism produces alcohol, carbon dioxide, and other compounds.

Wine, Whiskey, Tequila, Meade, Cider, and all other spirits known to man go through the same process of fermentation, so what makes beer different? Many of the sugars that the yeast eat are similar across different spirit classes, so what makes these different from beer is really where the sugar comes from. Beer is mostly made from barley grain, but it can also be made using oats, wheat, and other cereal grains.

Milling

Grains are composed of carbohydrates, which are actually a bunch of smaller sugar molecules joined together. Yeast cannot eat carbs, so in order to feed the beast, you need to break down the grains into smaller sugars. Thankfully, grains have enzymes in them that do this for you! All you need to do is crack open the grain, or expose the inside of the kernel. This is done usually using a grain mill, which is composed of 2 rollers that crush the kernel in between them. Once all the grain is crushed and the kernels exposed, you can move to the next step.

barley_crusher_rollers_large

Mashing

This is one of the most important steps of making beer, if not the most important. Mashing is when you take the crushed grain and add water to it. In layman’s terms, you simply let the grain steep in hot water like you would a tea bag for about an hour, and the carbs break down into sugar.

In reality, it is not so simple. The water needs to be in a certain temperature range, roughly 145 to 165. Not hot enough? The enzymes will not break the carbs down to sugars. Too hot? Same problem, along with other issues. Is is important to get the temperature just right. “Just right” depends on which kind of beer character you are going for, and it is too advanced for this article.

Water chemistry is also a huge factor in how effectively the enzymes inside the grain break down the carbs into sugars. One needs to make sure the pH, or acidity of the water, is just right in order to ensure the most efficient amount of sugar breakdown.

Sparging

Some brewers actually don’t sparge, but we do. Sparging is a process where you rinse the grain with more water to get all the sugars off. The better you rinse the grain of all the sugars, the more sugar you will get in your beer, which will mean more alcohol. There are multiple styles of sparging, but we like to fly sparge. This is where you essentially slowly trickle water from the top of the pot while simultaneously draining the bottom into your boil pot. It is important to do this slowly, as you want to thoroughly rinse all the grain.

fly-sparge

Boiling

After rinsing all the grain into your boil kettle, now is the time to cook it by bringing it to a boil. Boiling the beer pasteurizes it, or kills any bacteria that may be present. This is essential because you do not want anything other than the yeast you will later add present in the wort (wort is unfermented beer). You usually boil the beer for an hour, but some beers require a longer boil.

The boiling step is usually where you add hops. Cooking hops is very similar to cooking an onion. Think of sauteing an onion on the stove top. The longer you cook that onion, the more the onion breaks down and actually loses its onion flavor. The shorter time you cook it, it still tastes and smells pretty much like a raw onion.  When you add hops in the boil, the earlier you add hops, the more bitter the beer will become. This is because you are cooking those hops for a long time. When you add hops later in the boil, the oils on the hops are not broken down as much, so the beer retains more aroma and flavor from the hops. Sometimes, you even add hops after you are done boiling, so they are not boiled at all. This is usually a process called whirlpooling, and it done as you are letting the wort naturally cool down, but never letting the wort get below 180 degrees.

Cooling and Transfering

After boil, you are ready to transfer your wort to your tank in order to begin fermentation. The most important thing to do in this step is cool the wort as fast as you can. Why? Because once the temperature gets below 180 degrees Fahrenheit, bacteria is able to grow. You want to give your beer as little chance as possible to spoil. This means keeping anything in the outside world from getting in, and also cooling the wort down to room temperature in order to add yeast (bacteria thrives in hot temps). Most brewers use a plate chiller, which is exactly what is sounds like: many small copper plates put together that you run water through. The wort is run on the other side of the plate, and because copper is a good conductor of heat, the heat from the beer transfers to the water until the 2 are the same temperature, essentially chilling your wort.

plate chiller cut

Above is a plate chiller cut open to reveal the inside. These chillers are very effective and will bring boiling hot beer down to room temperature in as little as 20 minutes or less depending on the volume and size of the chiller.

Aeration and Yeast Pitch

Once the beer is in the tank, or in some cases while it is being transferred, it is important to aerate the beer with pure oxygen. Why do you do this? Without getting in the weeds, yeast need oxygen at first in order to grow. Too little oxygen will not allow the yeast culture to grow.

After aeration, you want to pitch the yeast, which is simply a fancy term for adding the yeast to the wort. It is important to make sure you add the right amount of yeast, measured in cells, to the wort. Too much yeast for your wort, and the yeast will eat up all the sugars and then end up with nothing left to eat, which can cause off flavors in your beer as well as other issues. Too little yeast will not be enough to eat all the sugar, and you will end up with a sweeter beer or one that is lower in alcohol than you intended.

Fermentation

One of the most vital processes of making beer, now is the time for the yeast to go to work. This usually takes anywhere from 5 to 10 days depending on the type of yeast, amount of yeast, or amount of sugar present in your wort. As the yeast eats the sugar, the excess CO2 will leave the tank usually through a hose, which is in turn submerged into a bucket of water. Next time you tour a brewery, look for spackle buckets on the ground next to the tanks bubbling like crazy.

The temperature range for fermentation varies by the type of yeast strain and desired characteristics of the final product, but usually ale yeast will work best in the 65 to 75 degree range, while lager yeast works better at colder temperatures, usually around 50 degrees.

It is important to NEVER rush your beer, and by that I mean emptying it out before it is finished. Many brewers gauge yeast activity by the bubbling of the CO2, which is the wrong way to do it. Even if you do not see bubbles, the yeast could still be eating. Rushing the beer will not give the yeast proper time to eat the sugar as well as digest any other off products of the beer such as DMS (advanced subject for this article).

Cold Crash, Carbonation, and Packaging

Once your beer is ready, you will want to cold crash the beer. This is done by bringing the temperature of the tank down to as cold as freezing as possible. The yeast begin to flocculate, or stick together, and actually sink to the bottom. This is good, because most beer styles you do not want yeast floating around in it (some you do!).

Once you properly crash the beer, you can now transfer it to secondary vessel called a brite tank to carbonate it. This carbonation process usually takes 1 to 3 days. Below is an example of what a brite tank usually looks like. It usually does not have the same coned bottom that a fermentation vessel has.

ss-brewtech-brite-tanks-1-bbl-ss-brite-tank-721763106835_1024x1024

Once you are done carbonating the beer, it can now be transferred to bottles, cans, or kegs – brewer’s choice!

Make Science Fun Again

As someone who started brewing beer as a hobby, I was shocked by how much biology and chemistry go into making a beer. Any fool can make beer; it was made by accident thousands of years ago. But it takes a scientist to perfect the beer and make it taste great. I bet if they let kids brew beer in school (not drink it, calm down people), more kids would fall in love with the sciences. Drinking beer is fun, but so is making it!

 

 

 

 

%d bloggers like this:
search previous next tag category expand menu location phone mail time cart zoom edit close