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Budweiser American Ale

FEATURES


It's a Gas!

From Velvety Foam to Rocky Head

by Ray Daniels

Portland Brewing PictureSit at a bar for any time at all and you'll notice that beers don't all pour the same. Some have no head; some have a lot. Some yogurt-thick foams will stick to your lip so that you look like one of those "Got Milk?" ads. A few will push up Everest-like crags in mid-glass. Other heads vanish with the first sip. And below the foam, more action. Some beers swirl and dance in the glass; others just flop in there like a ladle-full of chicken soup.

 

• Introduction • It All Starts with Gas
• Clearing the Confusion
• Putting It In •It's in the Tank • Heady Issues
• Into Thin Air?

 

s a beer drinker, you probably have an opinion about the amount of head you like on your beer and the way it should look when it fills the glass. What you are less likely to think about is the root cause of these conditions: beer gas.

Most beer drinkers take the gas in their beer for granted. Some even wish the gas—and its various effects—would go away. But researchers and brewers have spent two centuries building the scientific knowledge needed to perfect today's current combinations of gas and beer. The resulting mixtures not only tickle tongues and torment tummies, they also bring a sparkle to the spectacles.

Oh, but the science. Surface tension and nucleation sites. Partial pressures and protein matrixes. And a list of principles so firmly anchored in reality that even the scientists call them laws: the Ideal Gas Law, Henry's Law and Dalton's Law. (But not, somehow, Beer's Law.)

Can it really be all that complicated? After all, beer has been around for five millennia—longer than science itself. All we beer drinkers want is really quite simple: to watch a beverage settle into a glass with a firm cap of foam and then provide us with a gentle prickle on the tongue. Is this so hard to achieve?

If you look around at the beverage world for a moment, you will see that perhaps it is. Beer, after all, presents a unique combination of physical characteristics. The simple tingle of carbonation is the easy part. Both soft drinks and champagne manage similar effects. What's tough is that fob of foam on the top. Just take a gander at the next doppelbock or oatmeal stout that lands in front of you. No other carbonated beverage produces an enduring frothy firmament like that found on a good beer.

So let's check it out. As proud beer drinkers, we're entitled to appreciate these distinctive details of our favorite quaff. When it's all over, we'll take a look at where all the gas in your glass goes when you guzzle.

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Ray Daniels is an internationally known expert on craft brewing. He is the founder and organizer of the Real Ale Festival and the author of several books on great beers and homebrewing.

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This story originally appeared in All About Beer Magazine in January 2000.


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