Head on Beer
Last Updated : 05/04/10
Fancy a thick, creamy head on your beer?
write this as a proud northerner who likes his beer from a handpump not direct from cask and, preferably, with a loose sparkler attached. I can almost hear the shrieks of anguish, wringing of hands and disapproving tutting that comment will provoke, but I make no apologies for my opinion which has been honed through many years of drinking; I simply feel that beer served via handpull with a loose sparkler tastes better than that straight from the cask as if, somehow, the process wakes up the beer and kicks it’s flavours into life.
The problem is that, over the last 50 years, greedy brewers have been trying to get more from a cask than will physically fit into it and one of their more insidious methods of doing so is the thick, creamy head. The king of short measure must be the Irish Stout brewers whose beer is marketed as having a substantial velvety beige collar atop the beer itself and they have achieved their brainwashing so completely that I've seen drinkers happily walk away from a bar with a glass 3, 4 or even 5cm below the brim. Now these brewers – mainly owned by multinationals, tellingly – have an advantage in that their beer is nitrogenated but that hasn't stopped other avaricious brewers trying to get in on the act.
Beer foam “consists of polypeptides of five different classifications divided by their relative hydrophobicity; as the hydrophobicity of the polypeptide groups increases, so does the stability of the foam” which makes very little sense to me but I’m sure it does to some people! Consumers want a head on their beer for various reasons including social conditioning and where they come from and, despite beer with no head having more dissolved CO2 than that with a head (as the gas is taken out of solution to form the bubbles in the head), it’s often said to be “flat” which just goes to show how much most beer drinkers know…
Anyway, back to the Chemistry/Capitalism lesson; an obvious method of getting more from a cask is to top it with a “Mr Whippy” head, meaning there is less room in the glass for beer as the foam – which does contain a small percentage of beer – takes up space which should be occupied by beer and, as you can appreciate, beer costs more than foam whilst foam takes up more space than beer leading to a “double whammy” value-wise for the drinker. There are various ways of creating or improving this head before, during and after the brewing process, some of which you may not realise:
1) Use a sparkler. Loose (adjustable) ones allow the landlord to vary the amount of backpressure the handpump creates therefore enabling him to set the perfect tightness for each cask resulting in a textbook head, but those little white fixed ones aren't good for beer; they create huge backpressure meaning the handpump must be pulled hard giving those glasses of pure white foam and, consequently, knocking all condition out of the beer and most of the hop oils into the head; not many beers are brewed to be served this way!
2) Use Wheat malt in the mash. This is a common ingredient in beer, usually 10% or less of the mash, and for some complicated chemical reason (mainly due to the high protein levels it contains) it causes the head to last longer and be more stable and “lacy”. Before anyone moans that beer should be 100% malted barley I'll simply say read up on brewing and you'll see that a percentage of adjuncts is generally considered to be good and prevents, amongst other things, protein haze.
3) Crystal malt and other “cara”-type malts can also improve head retention by adding dextrines and other complex proteins, although this comes at a cost as the overuse of such malts results in proteins reacting with tannins to create a chill haze which, in the UK at least, is very undesirable in cask ales. Used in moderation, though, Carapils and the like can significantly increase head retention and lacing in the finished beer.
4) The Autovac. This endangered contraption, mainly found these days in Yorkshire and Scotland, allows beer overflowing the glass into a collecting tray with a pipe underneath then mixes this reclaimed ale with fresh beer from the cellar upon which the mixture goes back into the handpump. Obviously if glasses are re-used there's a high potential for beer contamination which is why Autovacs are extremely rare these days; a good sign one is in use is the handpump being thrashed for all it's worth and rows of pints being arranged on the bar to settle.
5) Use Heading agents. Now we come to the less wholesome side of beer production, the chemical additives. As far as these go PGA Powder - Propylene Glycol Alginate – isn't actually that bad, usually being derived from kelp, but it's still an unwelcome thing in my opinion. PGA is an emulsifier, stabilizer, and thickener used in many food products, beer and yoghurt being two, and is registered food additive E405. Chemically, propylene glycol alginate is an ester of alginic acid, itself fairly natural, but surely there's no need for such things in beer which, after all, is supposed to be a natural and wholesome product? For the record, PGA “improves the performance of the bubble, increases the bubble's adhesive ability and improves the beer's appearance” and even “Makes the bubble more exquisite”, whatever that means.
Another common enzyme used for head retention is Pepsin, generally derived from pork, which works on protein present in the beer and, through some alchemy I neither know nor care about, this contributes to head stability.
6) Use more hops! Isohumulones – alpha acids from the hops, isomerised when the wort is boiled – can help the retention of the head by lowering the surface tension and making the foam more elastic in structure, therefore lasting longer and being more stable. High-alpha hops are better for head retention as, obviously, they contain more alpha acids than low alpha hops although all hops will help to some degree.
7) Make the beer weaker. Alcohol is a “foam negative” substance and makes the head more unstable and liable to collapse as it weakens the wall around the bubbles, making them burst and therefore release the beer they are comprised of back into the pint.
8) Get the PH right. A PH of 5.6 is ideal for foam retention which, combined with a higher mashing temperature that means more proteins in the beer, will increase the head retention and stability.
9) Ensure the liquor used in brewing has the correct balance of salts and minerals. Although it’s not always possible to do so for all styles of beer, if iron, nickel and zinc salts are present in the correct quantities and concentrations this makes the foam more stable.
10) Serve the beer under top pressure or a mixed gas blanket. Top pressure is basically putting a pressure of gas, generally Co2, on the beer which absorbs some of it making the beer far more likely to have a head when it comes out of the pump. Mixed gas is generally used for those atrocious “creamflow” type keg beers but the cylinder can easily be plugged into a cask spile with exactly the same result as top pressure except, as Nitrogen is involved, the creamy head will be even more noticeable.
11) Another method is that demonstrated to the “Real Ale Twats” in Viz a few years back, but you really don't want to think about that... honestly, you don't.
Still fancy a thick, creamy head on your beer now? No, I didn’t think so…