Issue Date: November 2, 2015
Helium Beer, From Prank To Tank
Squeaky-voiced brewers have released videos over the years promoting limited-edition beers pressurized with helium instead of carbon dioxide. The videos post on or around April 1; April Fools’ Day pranks, one and all.
A quick Internet search yields several pages explaining how helium beer is impossible because of the low solubility of helium in water. Indeed, helium’s solubility, 0.0015 g/kg, is roughly three orders of magnitude less than that of carbon dioxide, 1.7 g/kg.
And then the Newscripts gang took pause: A nearby listing on the same data table notes that nitrogen’s solubility is 0.019 g/kg. That’s not as low as helium, but still much lower than carbon dioxide. Yet beers such as Guinness famously use nitrogen in place of carbon dioxide to achieve a creamy mouthfeel and a fine, stable head of foam.
So we decided to make our own helium beer. For real.
Most homebrewers brew beer in 5-gal batches and either bottle it or keg it. In the fermentation process, yeast converts sugar to alcohol and carbon dioxide. When bottling, a little extra sugar is added, which builds up pressure in the bottle and carbonates the beer. When kegging, it’s easier to hook up a tank of carbon dioxide to the sealed keg, a process called force carbonation.
Our concept was to swap out the carbon dioxide tank with a helium tank. Instead of force carbonating, we would force … heliuminate.
We teamed up with chemist and experienced homebrewer Kevin Wepasnick, a surface scientist at Anderson Materials Evaluation.
Wepasnick chose a cream stout beer style that ferments for about two weeks. While we waited, we asked beer chemistry experts to weigh in on what helium would do to our brew.
Stanford University’s Richard Zare, who investigated the motion of Guinness’s nitrogen bubbles, said, “I do predict it will lead to higher-pitched belches.” Zare predicted that because helium is essentially insoluble in water, any bubbles that formed would float to the top without changing size or speed. However, he said, those bubbles could pick up any dissolved carbon dioxide and therefore grow and accelerate as they rise.
Charles Bamforth, the Anheuser-Busch Endowed Professor of Malting & Brewing Sciences at the University of California, Davis, pointed us to Ostwald ripening, a process in which bubbles grow larger by feeding off nearby smaller bubbles. The net effect is a coarsening of the foam. Because the gas molecules must travel through bubble walls, the process is limited by solubility.
“What this means for our beer is that the head should be rich and creamy and last a long time,” Wepasnick predicted. Ostwald ripening also occurs in solid materials and on surfaces, his area of expertise. “I am expecting the effect to be similar to nitrogen, although the diffusion of the helium out of the bubbles might limit the head lifetime compared to nitrogen.”
Brewers monitor their fermentation by measuring the density of the brew. As the yeast converts the sugars to alcohol, the density drops. When that density stabilizes, it means the beer is ready to bottle or keg. The final density is also used to calculate the alcohol by volume, or ABV. Our final ABV was 6.2%.
When fermentation of the Newscripts brew was complete, Wepasnick placed the beer under 50 psi of helium pressure for around five days in a chilled keg. He then dialed the pressure down to a more normal serving pressure, 7 to 10 psi. The Newscripts gang traveled to Wepasnick’s lab to finally taste real helium beer.
Our helium stout produced a creamy, stable, well-proportioned head, which persisted through the last sip. The mouthfeel was smooth, with very little of the bubbly texture normal carbonation brings.
In other words, other than the nice head, it was pretty much flat. That said, it was similar in fizzyness to Guinness poured from their nitrogen-infusing draught can, which we had on hand to compare.
In aqueous solution, carbon dioxide converts into carbonic acid, giving carbonated beverages an extra bite. Helium does no such thing, which gave the helium beer additional smoothness relative to a conventional carbonated brew. “This is a recipe I would make over and over and over again,” Wepasnick said. “But I wouldn’t waste helium; I’d use nitrogen instead.”
The pitch of our voices and belches, sadly, was unaffected.
Craig Bettenhausen wrote this week’s column. Please send comments and suggestions to firstname.lastname@example.org.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © American Chemical Society