I am sure across the globe beer lovers, haters, bartenders and brewers all have different opinions on the matter of beer foam. You know, that beautiful collar of creamy CO2 and protein on top of your beer? So, obviously I am a proponent of foam on a properly poured beer – if you have seen any of my beer reviews you’ll notice every picture showcases a beer poured with at least a little foam cap, but usually a significant one (like the dense and sumptuous head on top of the Anchor Christmas Ale pictured above). I believe that foam on beer has several benefits to the beer drinker throughout the entire experience; and it all starts with your eyes.
Although everyone will certainly have a different idea of what makes a beer beautiful, I have to argue that a clean and defined foam cap on top of a well poured beer in a beer-clean glass takes the experience from delicious to symphonic. Right away when you pour your beer you will begin evaluating and judging it. Your eyes will notice its color, its transparency, and how much foam it is producing. This all may indicate to you its carbonation level, and give you an idea of the potential flavors to come – but the foam atop that beer will suggest to you its viscosity and mouthfeel, as well as its overall purpose. Think about it like this – two golden beers, both transparent and bright – one with a bright white head and medium to large bubbles that pop and crackle as they touch the air. The other has an eggshell colored foam that is dense and creamy with very tiny bubbles that persist against the air trying to ravage it. One of these beers is going to be crisp and quenching, the other more supple and gratifying…
That rich foam also makes a pint, mug or snifter of beer look that much more appetizing. To me at least. But really its not just me. Big breweries have spent many shekels researching what consumers want out of their beer – and consistently the surveys show that people are more willing to spend their hard earned money on a beer that shows decent foam than one that appears tepid without any. Just try it yourself; pour two beers, one with foam and one without. Which do you want to drink?
So lets say I’m right – foam makes beer look prettier and more appetizing. But its science’s turn now. One of the main reasons foam on top of your beer will enhance your beer drinking experience is that it protect the beer from harmful and spoiling oxygen. Its true. O2 is good for us, but bad for beer. If you ever get a stale cardboard aroma and flavor from your beer, oxygen has reacted with it to create an “off” flavor not desirable in beer (or any beverage for that matter). The process of spoiling called oxidation generally does not happen rapidly, but it does begin immediately – trying to harm your beer and ruing your experience. It is worth noting that slow and controlled oxidation of specific styles of beer can lead to very desirable and delicious flavors like sherry, port, and sweet leather. A vintage bottle of British Barleyine or Russian Imperial Stout is a good candidate for positive oxidation – but that’s for another long winded and geeked-out rant.
In general you do not want your glass of beer exposed to oxygen, so in comes foam to save the day. Those bubbles that I have been so lovingly discussing are there protecting your beer from oxygen. Each bubble is filled with CO2 produced by the beer; so the foam is an attractive and delicious barrier keeping your pint from oxygen and maintaining its brilliance. Not only are these bubbles keeping CO2 out, but they are helping to keep delicious aromas in! As you bring your nose to the beer, bubbles will burst as new ones form and they will deliver a controlled dose of aromatic enchantment to your awaiting senses.
After all of this what is really important though is determining how YOU will best enjoy your beer. I know for me a few inches of foam goes a long way in by beer drinking experience. But flavor, beer, and purpose are all subjective – so you will have to decide what is important to you and what makes your beer delicious. Or, if you don’t want to think about it, just listen to me. Cheers.