Why does the head on a beer persist?

When you pour any aerated drink you can generate a head, well froth at least. In the case of beer it persists but with anything else it dissipates. Why?

Now that I think about it if you make a spider (soda and icecream) you get a head you could walk on. So is it solids?

With a “spider” (we call them floats, here), I think it’s just the icecream thickening the liquid to the point that its bubbles are much stronger. It makes sense to me, anyway.

In general, suds in potable liquids are due to dissolved protein. Beer does have some protein in it, enough to keep a nice head. Things like soda pop being mostly sugar and water do not have any protein to speak of and so the head does not persist.

My WAG is that by adding ice cream to the soda in addition to adding more sugar and fat you are also adding enough milk proteins to make a head. Normally fats and oils make a head dissipate.

Yup, proteins are also major foam producers in urine and seawater.

Alton Brown goes into great depth on how proteins for bubbles in any number of episodes of Good Eats.

Thus the good Aussie phrases with piss as a substitute for beer - “piss artist”, “on the piss” etc.


Ergo, I’m right :D.

If the head persists for any longer than 5mins then you aren’t drinking it fast enough.

Does that mean Guinness stout has more protiens than most beers/ales/lagers?

I believe so. Not sure how this relates to the other well-known facts about it.
i.e. it makes you fat and turns your bowel movements the colour and texture of road covering.

Guinness is served with a N[sub]2[/sub]/CO[sub]2[/sub] mix known as “beer gas” that causes a lot more extremely small bubbles than straight carbon dioxide does. That is why it has such a dense creamy head.

Only in cans, not bottles (don’t know what they put in the kegs used for draft). Oddly, the bubbles sink instead of rising.

On my 365 Bottles of Beer For The Year calendar, today’s Lager Lingo says:

[quoye] Brussels, or Belgian, lace is the pattern of foam left on the sides of the glass as the beer is consumed. Well defined, long lasting patterns are often a sign of a well-made beer.

Guinness does have bottles with a rocket shaped widget that releases N[sub]2[/sub] similar to the way the widget does in the cans, but I was referring to draft Guinness Stout in my above post, just to clear up any further misunderstandings.

As far as bubbles in Guinness sinking goes, my understanding is that the bubbles on the edge experience drag from the sides of the glass and are pulled down by the rising current in the center of the glass. Obviously all of the bubbles do not sink as you would end up with a head on the bottom of your beer, which would be disturbing to say the least.

Yep. Stout brewers often use unmalted flaked barley in their mashes to increase the protein level and thereby increasing the head retention of the beer. Other malted grains (eg wheat) high in protein can be used to produce a nice frothy head in other beer styles.

Or more pee. :eek: