How to Get Better Head…on Your Guinness
Our St. Patrick's Day Experiment
Devotees of the Irish stout Guinness claim there is a science to achieving the “perfect pour” – a combination of temperature, angle, speed, motion, timing, and so on that produce a classic pint of the dark malty brew with a head of light, creamy, finely grained foam on top. However, since we don’t have access to a nitro tap, we wanted to see if there was another technique that would give us good head…on our Guinness.
There’s a Widget in My Beer!
The layer of foam on the Guinness pint is so legendary that Guinness has employed some pretty sophisticated technology to allow the average home consumer to enjoy an authentically frothy stout without the benefit of a nitro tap.
Starting in the 1980s, Guinness introduced cans and bottles of “draught” stout, which included a plastic capsule of pressurized nitrogen. When the can or bottle is opened, the nitrogen is released and surges through the beer, which also releases nitrogen that was absorbed into the beer during the pressurization process. This is what causes the “surging” effect that sends turbulent waves of bubbles through the beer and makes it take so long for a pint to “settle”.
More recently, Guinness introduced the “Surger”, a drink-coaster sized device that froths up a home-poured pint by using ultrasonic waves to release the bubbles. The Surger produces an impressive pub-worthy head in seconds (and a larger version is used in pubs that don’t have a tap line installed). However, it is available only in the UK (for the price of £16.99, or about US $35) and you have to use a special kind of canned Guinness that’s had more nitrogen forced into it.
We wanted to see if we could mechanically simulate the Guinness Surger’s effect and create an acceptable head of foam on a canned or bottled Guinness through other means.
Since the Guinness Surger uses ultrasonic waves, we got an ultrasonic toothbrush, which we at first intended to apply to the outer surface of the glass. This had no effect beyond the immediate area of contact. We then put the toothbrush head directly into the beer, and succeeded in frothing up an impressive head within seconds. Although the mechanical agitation and rapid vibration of the toothbrush is probably responsible for some of this effect, we think the ultrasonic frequency enhanced it. This was confirmed when we repeated the process using an electric toothbrush that was mechanical only, not ultrasonic. The effects of the non-ultrasonic toothbrush were similar but not as dramatic.
In the absence of authentic Guinness “Surger” beer, we chose to experiment with the non-nitrogenated Guinness Extra Stout (which contains only carbon dioxide) using the head on the widgetized Guinness Draught as a comparison. Contrasted to the thin layer of foam on the Draught pint, the beer frothed with the toothbrush produced a voluminous head such as you would expect to see in an actual draft beer. While the head on the nitrogenated Guinness had the characteristic off-white color, creamy texture, and fine-grained foam of a pub-pulled stout, the artificially frothed beer had a darker tan head with a coarser texture and larger, more irregularly sized bubbles. The reason for the difference involves the internal pressure and surface tension of the bubbles and the refraction of light, but it boils down to the fact that the Draught beer is pressurized with nitrogen and CO2, while the Extra Stout uses CO2 only.
Though the head on the toothbrush-frothed beer initially topped that of the canned Draught beer, it did not hold its structural integrity for nearly as long. Left undisturbed, the Draught head gradually thinned but remained remarkably consistent for up to an hour. The frothed head, on the other hand, began to degrade within minutes, collapsing in the center and taking on an increasingly irregular grain and “lumpy” texture as the small bubbles combined and formed larger bubbles.
We found that after the initial head had started breaking down, the beer could be “re-foamed” two or three more times, until all of the carbonation in the liquid was exhausted.
We also tried frothing beer with an electric hand blender. The rapid and turbulent blender action came closer to emulating the “surging” effect of the Guinness gadget. With the head submerged about 5cm into the beer, the briefest pulse of the blender was enough to release a torrent of foam that overflowed from the glass. While the resulting head was more profuse than the head produced with the toothbrush, it was coarser and also began to degrade fairly quickly. However, the blender had the virtue of being able to raise a head even on beer that seemed depleted by several foamings.
What’s the Frequency, Guinness?
In our third attempt, we tried to recreate the effect of the Guinness Surger using an inexpensive ultrasonic jewelry cleaner, the kind you see advertised in infomercials or on QVC. This model had the advantage of being the perfect size and shape to hold a pint glass. In theory, this device works the same way as the Surger: you put a small amount of water in it, and the ultrasonic waves are transmitted through the water and bounce against the glass, causing the beer inside to release bubbles, which rise and turn into foam. Instead of using the more nitrogenized Guinness Draught Surger beer, we substituted regular Guinness Draught, pouring it carefully to release as little of the nitrogen as possible.
While the Surger’s results are quite dramatic, ours were not. Something was going on in the glass, but at a very small scale. A few more small bubbles appeared on the inside surface of the pint, and some bubbling occurred on the surface of the beer in the middle of the glass as well, but it did not explode in a froth as we had hoped. Our conclusion is that the Surger probably uses a much higher ultrasonic frequency than our jewelry cleaner (which we estimate at around 30,000 Hz, given the normal range of these devices), and probably transmits it to the glass more effectively by using different materials and design.
A Perfect Pint Wasted?
The idea of attacking a pint of Guinness with implements like a toothbrush and a blender probably seems sacrilegious to Guinness purists. So why would anyone want to do it, especially when widgetized Guinness is available? Taste, for one thing. Pressurizing beer with a blend of nitrogen and CO2 alters the flavor and character of a beer (compared to pressurizing with carbon dioxide only). So Guinness draught in cans or bottles tastes noticeably different than Guinness Extra Stout. Nitrogen supposedly makes the taste smoother, but to our palates, the Guinness draught tastes watery, burnt, and bitter, while the Extra Stout has a more robust flavor. The draught beer also seems flat, probably since little gas remains in the beer by the time it’s been opened and poured.
So, if you want to put a head on a Guinness Extra Stout, or buff up the head on your draught stout, an electric toothbrush or hand blender will quickly whip up some passable foam (thought not by “perfect pint” standards) provided you drink it quickly enough. If you try this with a toothbrush, we recommend using a new or very clean one, since adding the flavor of toothpaste is a sure way to ruin your beer.