The Beer Fermentation Process Explained

Beer fermentation is something enjoyable and exciting to do. It lets you gain control over how your beverage looks, smells, and tastes, making the beer-drinking experience a lot more enjoyable. This process is the final step in homebrewing. 

Beer fermentation involves straightforward steps, mainly equipment sanitation, yeast pitching, waiting, and bottling. Most newbies are daunted by the fermentation phase, but with practice, beer fermentation can be quite simple.

In this article, I’ll discuss in detail the steps involved in fermenting beer. I’ll also go over the main types of beer, how the kind of yeast used dictates the taste and quality of beer, and the different ways you can influence how your beer looks, tastes, and feels. Let’s get started! 

A Step-by-Step Guide to Beer Fermentation

Beer fermentation has been around since before 6,000 BC. There have been a number of archeological findings dating back to the early civilizations in Egypt and Mesopotamia featuring relics that hold clues to ancient methods of making beer.  

Simply put, beer fermentation is the process where yeast converts the sugars in the wort into ethyl alcohol and carbon dioxide. Fermentation is what makes beer carbonated and gives it its alcohol content

Making beer in the confines of your own home is manageable and relatively easy. While it’ll take roughly 2 weeks for you to take the first sip of your very own homebrew, it’ll be worth all the hard work and patience. 

However, keep in mind that you practically have no control over the duration of the beer fermentation process. All you really do is pitch the yeast and wait for it to do its magic, but you can make tweaks in certain details, such as the temperature, to help shorten the time frame. 

If you want to try your hand at beer fermentation, here’s a step-by-step guide:

1. Gather All Your Tools and Equipment

Beer-making requires patience and focus. To help make the task easier, especially if it’s your first try at homebrewing, it would be wise to keep all the tools and equipment you need at hand. 

Here are the basic things you’ll need:

  • Sanitizers and cleaning gear. These help ensure that your beer will be safe to consume.
  • Fermenting vessel with seal and airlock. This is where all the action takes place. A seal and airlock are non-negotiables since they help prevent infection and oxygen exposure. 
  • Hydrometer. This is needed to measure your beer’s gravity and determine alcohol content.
  • Siphon. This will come in handy when transferring wort and beer from one vessel to another. 
  • Bottles/kegs. These must-haves are where the final products will be stored. 
  • Bottle caps. These will help keep beer fresh longer. 

2. Clean and Sanitize Your Tools and Equipment 

Use a sponge and a mild, unscented detergent to clean anything that may come into contact with your beer. Make sure to rinse well. 

Follow it up with a sanitizer, preferably one with no-rinse properties, for maximum effect and to minimize possible contamination when rinsing.

Why Cleaning and Sanitizing are Equally Essential 

Cleaning involves removing dirt, debris, and other unwanted particles on the surfaces of your tools and equipment. However, the process is merely skin-deep, attacking primarily visible components.

The Five Star PBW Cleaner Detergent (available on Amazon.com) is a great option for brewing equipment because it’s organic, alkaline, and non-corrosive. It’s reliable in removing thick dirt, even those that have been caked on over time, and frequent use. 

This is where sanitation comes in. This process gets rid of bacteria, unwanted living organisms, and deep-seated grime that may affect your beer’s taste and quality. 

Doing both will ensure that your finished product is great-tasting and safe to consume. Cleaning and sanitizing your equipment also helps prevent contamination

The FastRack Logic Brewing Sanitizer (available on Amazon.com) is a one-step, no-rinse formulation in powder form. It’s ideal for beer brewing because it gives a non-alkaline wash to all your tools and equipment.

3. Move Your Wort Into the Fermentation Vessel

Using your siphon, pour the base of the beer — called “wort” — into the fermentation vessel. Oxygen must be introduced into the vessel, and you can do this by pouring in the wort vigorously or rocking the vessel forcefully back and forth. 

Consider pouring fresh drinking water over your wort. This helps make up for the amount that will evaporate over time. 

4. Check the Wort’s Gravity

Using a hydrometer, take a sample from your wort and check for its original gravity. You’ll essentially be measuring the density of your wort’s fermentable sugars

You’ll have to measure the final gravity of the wort later on in order to determine the alcohol by volume (ABV). This lets you in on the alcoholic strength of your beer and how it will taste. Generally, beers with higher ABVs are more robust and harsher. 

5. Add the Yeast

Also known as “pitching” the yeast, it’s time to add the yeast to the wort. Depending on the type of yeast, you can pour it over your wort or allow it to start working from the bottom to the top.

However, before beginning the fermentation process, you must allow the wort to cool down. Most brewers typically start once the wort has reached 70 ºF (21 ºC), while others begin when the wort is a bit warmer. 

It all depends on certain factors, such as:

Yeast Strain and Vitality

There are some yeasts that work perfectly well when warm, while there are others that only work when cool. This is why it’s essential to read your yeast’s packaging to know what temperature is optimal

Beer Classification

The 3 major beer classifications, which depend on the type of yeast used during fermentation, are:

  • Ale: Saccharomyces cerevisiae is the type of yeast used for fermenting ale. It requires temperatures ranging from 60°F to 80°F (15.5°C to 27°C). It ferments quickly, sometimes making beer ready for consumption within only a week. The yeast used in ale can also add fruitiness and spice to the beer. 
  • Lager: Saccharomyces uvarum is the type of yeast used for fermenting lager. It requires temperatures ranging from 45°F to 55°F (7.2°C  to 12.8°C). Lager is a bottom-fermented beer. This process involves yeast working its way through the wort from the bottom all the way to the top. Lager beer is typically clearer and crisper.
  • Lambic: Wild yeast or bacteria is used in fermenting lambic beer. It can be intentionally added to the wort or spontaneously incorporated. With spontaneous fermentation, the wort is left in an open vessel where nature is allowed to take its course. 

Some brewers also sometimes utilize the naturally occurring yeast in the skins of fruits, called Brettanomyces, to aid with the fermentation process. By simply adding fruits to the wort, fermentation and flavors are enhanced.

Bacteria can also be added to the wort. You can opt for lactobacillus for that sour beer flavor or acetobacter if you like vinegary hints in your beer. 

When it comes to lambic beer, fermenting involves a complicated, incalculable process. This is why authentic lambic beers take time to come by. Those that fall short of the rigorous process are aptly referred to as lambic-style beer

External Temperature

Fermentation is an exothermic process. This means it can generate its own heat, sometimes going as much as 20°F  (11°C) within a couple of hours.

It’s important to note that it’s crucial to keep temperature fluctuations at bay within the first 12 hours of fermentation. Fluctuating temperatures can make the fermentation sluggish, exposing your beer to bacteria growth.

To cool your wort, try wrapping the vessel in damp towels or submerging half of it in some water with ice

6. Seal and Secure the Fermentation Vessel

You can seal your fermentation vessel by attaching a stopper and an airlock gadget. However, remember to fill the airlock with some clean water.

Adding liquid in the airlock prevents air from seeping into the fermentation vessel. On the other hand, it will allow carbon dioxide to escape in the form of water bubbles. This is essential since wort demands an anaerobic atmosphere to properly ferment.

7. Keep the Fermentation Vessel in an Ideal Location

Finding the perfect spot for the fermentation process is crucial to your homebrewing success. Wherever you choose to store your vessel, keep in mind that the sun should never touch your fermenting beer and that temperature should be pretty stable

Ideal locations for beer fermentation include:

  • Dark closet
  • Dingy basement
  • Refrigerator (to have better control over temperature fluctuations)

8. Begin the Waiting Game

Leave your wort to properly ferment. Check your fermentation vessel every day or every other day and note any progress. 

For instance, you should see bubbles in the airlock within the first two days. This means that the fermentation process is well underway. 

9. Bottle Up Your Beer

A sign that the fermentation process is complete is when bubbles have significantly reduced or completely stopped forming inside the airlock. 

Depending on what type of beer you’re making, wait a week or two for the entire fermentation process to conclude.

However, some brewers recommend a more precise and scientific way of ensuring that the fermentation process has indeed been successfully completed — by measuring specific gravity over 2-3 days.

Once measurements have stabilized, it’s a sign that the fermentation step is done. Your trusty hydrometer will again be the perfect tool for this task.

Transfer your newly fermented beer into a bottle or keg. You may add bottling additives of your choice, such as gelatin, priming sugar, or polyclad. 

Bottling additives are essential in improving specific beer qualities, specifically carbonation. Remember that the fermentation process practically strips beer of sugars in order to create alcohol. Not conditioning your beer may result in it tasting flat and bland. 

10. Measure the Final Gravity 

Grab your hydrometer once again and take your beer’s final gravity. The gap between your original gravity and your final gravity helps estimate your beer’s alcohol content

Moreover, if your final gravity is higher than your original gravity, this means that more sugars are left after the fermentation process, so you end up with a sweet, malty beer. On the other hand, a lower final gravity tells you that your beer has a crispier, drier taste

Optional: Secondary Fermentation

This step isn’t typically necessary, but some brewers choose to undergo this to produce a smoother, richer taste. Secondary fermentation helps get rid of the sediments that usually settle at the bottom of beer bottles and kegs. A cleaner, crisper brew is thus produced. 

Using a siphon, simply transfer your newly fermented beer into a new fermentation vessel. A glass carboy is typically used for this step, and the process can take as short as two days or as long as several months, depending on the type of beer. 

For example, while ale will typically take about a week in secondary fermentation, lager beers can take months.

However, note that secondary fermentation involves some risks. For instance, transferring your newly fermented beer to another vessel might expose it to oxygen, which can encourage the growth of bacteria.

Secondary fermentation can also force your beer to become stale or absorb unwanted flavors, affecting its taste and overall quality. 

11. Store Your Beer Bottles

You can’t enjoy your beer just yet. Allow your beer to properly carbonate by keeping it in an area with stable room temperature for about 2 weeks. Once the beer is ready, you can safely store it in the refrigerator for later enjoyment.

Key Takeaways

Beer-making is an engaging, challenging, and rewarding activity. The fermentation process may seem daunting, especially since it calls for the use of yeast. If you’re like me, this type of fungus is deemed extremely complicated and tricky to handle. 
However, with enough know-how and practice, making your own beer can eventually become an easy feat. All it takes is understanding the processes involved, following instructions, knowing what signs to watch out for, and being bold enough to take on experiments and risks.

About HomeBrewAdvice

Hello, my name is Simon. Together with a group of writers I write about brewing beer and making wine. We all share a passion for the great things in life, such as making stuff from scratch.

The business of HomeBrewAdvice is to bring you great information, stories and product reviews from brewing at home, and making wine


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