Foam on draft beer: causes, solutions and tips for pouring it just right

Not too much, not too little. Too much foam, or the lack of it, can be warning signs, both for those who sell and for those who drink.

And you need to keep an eye on the health of your beverage. The first thing that needs to be said is: Yes, foam on draft beer is normal. But there is a right amount! Ready to find out everything about the subject? Then let's go!

What is foam on draft beer?

The foam on draft beer is nothing more than carbon dioxide, the same gas that pushed your beer out of the tap, trapped in the tension of the liquid, forming bubbles. When the tension is weak, the bubbles disperse into the air and the foam fades away.

Two elements help keep the foam in your glass for longer: proteins and hop acids. Because these substances do not mix with the water in the beer, they end up adhering to the foam, keeping the bubbles around longer.

Why does draft beer have foam?

Besides carbon dioxide, there are other substances that influence the amount of foam on draft beer:

• Alcohol: The amount of alcohol has a big influence on the foam on draft beer. Beers with higher alcohol content naturally have less foam, because alcohol lowers surface tension;
• Temperature: Besides affecting how the flavor of the beer is perceived, temperature can interfere with the texture of the foam. At higher temperatures, the amount of foam increases and it becomes more porous in the glass, and the amount of foam in the kegs also increases;
• Nitrogen: Nitrogen gas, when mixed with CO2 in the gas cylinder, tends to produce a creamy, full-bodied head.

What is the function and importance of foam?

In Brazil, it is very common for people to ask for their beer or draft beer with no head. What many people don't know is that the foam on draft beer is important in several ways, from enhancing the aroma of the drink to helping keep it cold.

The foam on draft beer is even cultural in countries like Germany, where the head in the glass is truly seen by most of the population as a sign of beer quality. It is hard for a consumer to accept a beer with no foam.

The benefits of foam

• The foam is made of CO2 molecules, which carry the beer's aromas. Therefore, a well-formed, consistent head will enrich the tasting of the beer;
• It helps maintain the temperature of the liquid in the glass, since it works as a barrier between the beer and the air;
• It prevents the beer from coming into contact with the air, minimizing oxidation, which leads to the formation of unwanted aromas. For this reason, a draft beer served without foam will oxidize more quickly, gaining bitterness as the minutes pass;
• It helps in recognizing the health of the beer. A draft beer that doesn't foam may have a carbonation problem, contamination or an expired shelf life;
• There are some beer styles, such as Belgian ones, in which a big head is part of the look.

The main argument Brazilians make against foam is that it takes the place of the liquid. On that point, don't worry: according to experts, 70% of the foam returns to liquid form.

Appearance of the foam

It is often said that there are two things that can be analyzed in beer foam: formation and persistence (or retention). The first concerns how well formed the foam is, that is, how uniform the bubbles are. The second is how long the foam lasts in the glass.

Checking the appearance of the foam is a very important part of a tasting. It can be used as a criterion for assessing the quality of the beverage, giving clues about the history of the beer in front of you and about how it was served.
Little foam can mean little carbon dioxide in the beer, or little protein or hop acid.

Are you a draft beer producer?

Stay alert, because some production problems, such as contamination and the formation of unwanted substances during fermentation, can also ruin the foam on your draft beer.

Problems with the draft beer dispenser, including a dirty coil, wrong pressure and wrong temperature, can change the character of the foam and the quality of the beer as a whole. If you want to learn more about cleaning the draft line and how dirt can affect your beer, read our post on how to clean the draft beer line.

It may seem fussy, but it's not! In fact, in beer competitions, the appearance of the foam is rigorously judged depending on each beer style.

In general, the foam should be lighter than the liquid, glossy, with fine, stable pores, which should remain for two or three minutes after the beer is served.

Causes of excess foam

So we reach a conclusion: foam on draft beer is good, yes! But, however, nevertheless: too much foam is good for neither the beer nor you. There are a few reasons why the foam level may be above normal:

CO2 pressure too high

The pressurized gas inside the cylinders helps carry your beer from the keg to the tap. This pressurized gas forces the beer out of the keg through the draft line, traveling to the tap you will use to pour your customer's glass.

Each draft beer has a specific amount of carbon dioxide that should be pushed out of the keg. If this amount of CO2 is exceeded, the molecules accumulate in the glass, forming a very big head.

We call this process over-carbonation, when the CO2 level is too high and builds up in the glass. What must be done is to adjust the pressure using a main regulator.

myTapp tip: we recommend using a mix of CO2 and nitrogen, which maintains pressure but prevents over-carbonation of the beer, and also creates a creamier foam when pouring a draft beer.

Draft beer too warm

The higher the temperature of the draft beer, the more foam is generated in the keg and, consequently, the wider the head in the glass. If you use a cold room for dispensing, you will hardly have temperature problems, since all the stock and lines will always be cold.

The beer warms up in the tubing

If your cooling happens far from the dispensing tap, the draft beer will warm up on the way, and when draft beer warms up, the foam increases. The keg inside the cold room and the tap are connected by tubing, and the farther apart the keg and the tap are, the longer this tubing is and the longer the path the beer has to travel to be dispensed.

The solution would be a python tube, or glycol line, which is a tube that “wraps” the draft lines running from the pre-chiller to the taps, keeping the entire draft line refrigerated.

Beer stone deposits

These are gray or brown mineral deposits, coming from calcium oxalate, that build up and eventually flake off if the system is not properly cleaned, leaving the beer with a bad taste and increasing the foam on draft beer. To avoid beer stone, you should clean your draft line monthly.

But let's say you bought a beer that should have good foam formation, yet when it came time to serve it, hardly any appeared. A few factors may have contributed to this:

• The pressure in the gas cylinder may be too low;
• Some connection or seal in your draft line may be open and gas may be leaking through it;
• The beverage may have a factory defect, such as contamination;
• Poorly washed glasses, or ones with residue from the detergent itself, can scare off the foam.

How to pour and form just the right amount of foam

The way you pour the draft beer has a big influence on the amount of foam that comes out of the tap. The farther the bottle is from the glass, the greater the impact of the beverage in the glass, which contributes to more foam. When you tilt the glass and pour the liquid slowly, the head tends to be smaller.

The ideal amount is at most about 3 centimeters, or two fingers, of head. But don't forget that, as we have already said, each style has different characteristics for forming beer foam.

With self-pour draft beer at your bar, your customer experiences dispensing draft beer and discovers the way they like best! Our screens indicate the need to tilt the glass when pouring, helping your customer through the self-pour experience!

Now that you have plenty of information on the right amount of foam on draft beer, it is essential to put it into practice and always keep an eye on it!

So, shall we talk so you can learn more about myTapp and self-pour draft beer?

I want it!