The importance of good head (idea)

“I believe a person who has never worn a beer-foam mustache is missing something.”
—Jim Dorsch

So what does the head on a glass of beer do? Is it, as many people feel, a barrier to the beer, at best a moustache decorator? Is it just for looks, or is there a deeper reason? Not everyone demands a good foamy glass, and there are local variations; in Norwich, where I began my drinking life, beer was served without head, but in the Midlands and North (of England) a good foamy head is expected.

Head is as much part of a good beer as good body, adding visual appeal and doing other surprising things. One of the things that a beer’s head does is traps molecules of the smelly stuff, releasing these aromatics with each little bubble that bursts. So a head adds not just to the appearance but to the enjoyment of the brew.

A Little Science, and Kevin getting excited about froth

So what does make for good head? Hydrophobic polypeptides, according to wikipedia. In simple English, this means strings of amino acids that repel water. Doubtless some clever chemist¹ will seek to be more accurate, but that will work for me. These chemicals disagree with water to the extent that they get as far away from it as possible, rising to the surface where they form the bubbles that in turn make the foam. The amount of head produced depends on several factors, then – the chemical composition of the brew in question, and the carbonation (or nitrogenation, if nitrogen be the driving force).

There’s a big variation in differing beers. Adnams Bitter, the beloved beer of my late teens, produced a skinny cap of foam, whereas many of the Belgian styles produce such a head of foam that the breweries produce special glasses designed to handle the profuse frothiness. Most of the American bottled beers I’ve been sampling lately produce about a finger’s width of head when properly poured, but there is of course a good deal of variation there depending on the pouring style. Open the bottle and pour it straight into the bottom of the glass and you’ll get more, trickle it gently down the side for less.

Similarly, in draught beers, there’s variation depending on whether the beer is pumped by hand or CO2/nitrogen pressure – too much pressure or gas and the depth of head exceeds the depth of beer. This is a crime to the beer-drinker, who is paying for liquid, not froth. It’s damaging for the vendor too, as many pints of beer can be wasted by pouring off excess foam. For a long time in Britain, CAMRA campaigned for pubs to draw their beer so that the top of the liquid was at or above the pint line (which is marked on pint pots in the UK), and to this day, there’s a hue and cry raised if a pub consistently serves too much foam and too little beer.

A Little Beer Snobbery

“Head retention” is another thing you’ll hear about, which means what it says – how the head holds up over time. Smaller bubbles generally mean better retention, and so does the chemical makeup – if the surface tension of the bubble is great enough, the head lasts longer. Other elements come into play as well – the drier the glass the better the head, and a clean glass is essential for good formation and retention. Don’t believe me? Try a Belgian Duvel in a dry glass and a damp glass – in the dry glass you’ll get a pillowy head that stands up for ever, whereas the damp glass produces less. An experiment I have tried myself with the added advantage of allowing me to drink two glasses of the amber delight!

You’ll also hear about what happens to the head as you drink it – there’s even a term for the froth left on the sides of the glass as you consume. “Belgian lace” is the term I’ve most often heard, and of course there are those Real Ale Bores who can go on about this seemingly for ever. Oops, is that the time? Sorry.

Of course, brewers know their markets and their drinker’s preferences, and many add various things to beer to boost head and retention – sometimes as part of the genuine brewing adjuncts (wheat makes for a good head) but sometimes by artificial chemical means. The former is allowable, the latter is, to my mind, Just Plain Wrong, but then I am something of a beer purist, if not an actual snob.

¹ http://oz.craftbrewer.org/Library/Methods/Other/KunzeFoam.shtml

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