Imagine what a refreshing glass of beer looks like. It might be dark, pale, or amber in color, but one thing’s for certain – there’s a nice layer of foam on top of it.
Now, does beer foam really matter that much?
Absolutely, and not just because of aesthetics. In fact, it’s safe to say that beer foam makes all the difference between having a good and a great glass of beer.
Why is that? Let’s get into the science behind beer foam.
Foam Formation is a Natural Part of Beer Dispensing
Simply put, foam is a mixture of liquid and gas – with liquid being beer, while gas is carbon dioxide (CO2).
Where did that CO2 come from, you might ask?
As you know, malt is (possibly) the most important ingredient in making beer. It is packed with enzymes, proteins, and fermentable sugars, the latter of which are food for yeast.
During the brewing process, beer yeasts consume those sugars and convert them into alcohol, while expelling CO2.
While beer is contained (kegged or bottled), CO2 builds up and turns into bubbles. And when you open and pour beer into a glass, the bubbles of gas escape to the surface, creating a layer of foam.
Aside from sugar, malt also contains proteins, which play an important part in foam formation and stability. These proteins are hydrophobic, meaning their molecules repel water molecules. Instead of hatching onto them, these proteins hatch onto the gas bubbles and rise to the top of the liquid.
Factors That Influence Beer Foam
Several factors influence how much foam ends up in your cup when pouring beer.
Carbonation Level
As we established, proteins connect to gas molecules, creating foam. So logically, the higher the CO2 content, the thicker the foam.
However, the thicker it is, the faster it dissipates. So, by the time you’re halfway down your beer, there’s barely any foam in your glass.
On the other hand, low carbonation levels result in a thin foam, and that’s quite a lackluster brew. Balance is the key.
Keg Pressure
To retain carbonation while beer is stored, there must be pressure. Once opened, the pressure is released, allowing CO2 to escape to the surface in the form of foam.
Now, there’s such a thing as too high or too low pressure.
If you set it too high, too much foam will form. If pressure is too low, beer will pour flat. For most beers, the ideal pressure is 10-12 PSI.
Beer Temperature
As you know, yeasts work faster at higher temperatures. However, that’s not really a good thing when it comes to beer. The more they work, the more CO2 forms, resulting in excessive foam.
Ideally, you want to chill your beer to 39°F or lower before pouring to achieve the perfect foam.
Glass Preparation
First things first, the glass must be clean before pouring beer. By that, I mean well-rinsed, as residue detergent can remain on the inside, and it will affect the foam. Not to mention the taste of beer.
Remember what we learned about temperature? Well, pre-chilled glass helps in keeping your beer chilled, so that you can take your time enjoying it. Furthermore, wetting a pre-chilled glass reduces foam, while a dry glass will increase it.
Finally, the shape of the glass affects how foam forms and retains. For beer, you want to use a tall and narrow glass, as its edges reduce the ability for CO2 to escape.
Pouring Technique
The way you pour beer also affects how foam forms.
If you incline the glass at a 45-degree angle, beer will slide down the edges, creating little foam. However, we do want foam on beer. So, once the glass is ⅔ full, straighten it and continue pouring until full.
Beer Type
Different beer types have different foam characteristics. Since proteins are responsible for creating foam, this makes sense.
Wheat beers, such as Hefeweizen and Witbier, have higher protein content, so they’ll naturally foam more in your cup.
Hops also help with foam, which is why pale ales have that soft and silky-like mouthfeel.
Lager storage temperature, on the other hand, results in less foam.
Finally, stouts like Guinness use nitrogen instead of carbon dioxide, which leads to smoother, longer-lasting foam.
The Impact of Beer Foam on Your Beer Drinking Experience
How does foam affect your beer-drinking experience, you might ask?
First, its light, frothy texture softens the palate. It prevents excessive fizziness from CO2 and bitterness, mellowing harsh flavors and enhancing sweetness or hoppiness.
Then, the foam releases aroma compounds into your nose, which further intensifies flavor perception.
Finally, let’s not forget about visual appeal – beer just looks so refreshing with a layer of foam!
Why Commercial Beer Dispensers Also Face This Challenge
Achieving perfect foam is no easy task, and many beer dispensers face this challenge.
Commercial dispensers, such as bar taps and draft systems, require your constant attention. You need to monitor three parameters, temperature, pressure, and CO2 levels, to ensure you get the perfect pour.
In case your first pour of the day is always foamy, you’re not alone. This happens even in bars, due to pressure fluctuations, which can be caused by drops and rises in room temperature.
Some commercial systems combine CO2 with nitrogen to keep the foam under control, but that’s not a foolproof solution.
What is? Well, keeping all three parameters in check while beer is brewed and stored.
How to Reduce Foaming When Pouring Your Beer from the F1
Pouring the perfect pint should be a satisfying experience, but excessive foam can sometimes get in the way. If you’re experiencing too much foam when dispensing your beer, follow these troubleshooting tips to achieve a smoother pour.
1. Ensure Cleanliness of Beer Lines and Spout
After finishing a batch of beer and before starting the next one, detach the beer line and spout for thorough cleaning and disinfection. This helps prevent foam buildup caused by residue or contamination.
2. Prevent Over-Carbonation
During fermentation (especially between days 3–5 when fermentation is most vigorous), check that the keg pressure does not exceed 24 psi. A small number of backers may have received kegs with older batch lids, where the PRV (Pressure Relief Valve) may allow fermentation pressure to reach 30–40 psi, leading to premature over-carbonation. If this occurs, please contact the support email at support@igulu.com as soon as possible to request a replacement lid from the latest low-pressure batch.
3. Keep Your Firmware and App Updated
Ensure that both the F1 firmware and the iGulu app are up to date. Regular updates help prevent unexpected issues and ensure smooth operation. With the latest firmware version, users can customize the dispensing pressure range between 6–15 psi.
4. Proper Pouring Technique When pouring:
Adjust the beer flow rate using the clamp on the beer tube. Pinch the tubing closed using the clip, adjusting it to the narrowest setting that still allows beer to flow.
Hold the glass at a 45-degree angle and pour the beer along the side of the glass to minimize turbulence and excessive foam.
4. Manual Adjustment if Excess Foam Persists
- Disconnect the gas tube from the keg lid.
- Pull up the PRV to release all pressure from the keg.
- Restart the CO₂ mode in the cooling program and set the temperature to 37℉ and the pressure to 6 psi.
- Reconnect the gas tube.
- Let the keg sit for 48 hours before drinking.
FAQs
What is beer foam?
Beer foam is the frothy layer of bubbles that forms on top of a poured drink, caused by the release of CO2.
Why does beer foam?
When fermentation occurs, CO2 molecules are released. These molecules hatch onto protein molecules from malt and rise to the surface, creating foam.
What is the foam on top of beer called?
Beer foam is also known as the beer head or collar.
How much foam should a beer have?
Ideally, there should be about a half-to one-inch layer of thick foam on top of a beer for optimal drinking experience.
