I remember visiting the Brewpub at Lennie’s on my 21st birthday. As a newbie to craft beer, the bartender offered me a brewery tour and a variety of samples at the bar... who would say no? As he poured my samples, the bartender -turned beer school professor- explained the differences between the 3 different serving styles on Lennie’s beer wall; CO2, nitro, and hand-pull beers.
You’ve probably seen the check marks on the chalkboard and been curious... but perhaps were too afraid to ask. Don’t worry -- I’ve got you covered. I may not be pouring samples, but I can pass along the knowledge imparted on me.
Let’s start at the beer-ginning with the true OG - cask hand pull, a style that has been around for centuries. In the olden days, after fermentation, the beer was put in wooden casks, stored in the cellar, and pumped up into a pint. The beer passed through a sprinkler on the pull tap that infused the beer with atmospheric air (roughly 80% nitrogen and 20% CO2), giving the beer a nice head and smooth mouthfeel. But storing it in a 55° cellar makes the beer taste “warm” to those not familiar with this traditional European style. Nowadays, hand-pull casks have evolved into stainless steel “firkin” kegs and are generally stored in a cooler rather than in cellars. Hand-pull beer enthusiasts insist that this serving style best allows the beer’s purest flavors to shine.
If you’ve consumed a beer in the past 100 years, you are most likely familiar with CO2-- good ole fashioned, bubbly carbonation. CO2 beer became the predominant serving style as beer began to be transported longer distances (though ours are either made in-house or travel from the BBC production facility across town… cheers to fresh, local beer!). To prevent the beer from getting stale, kegs were pressurized with CO2, which kept oxygen out of the beer. The CO2 pressure also pushes beer through the faucet, so barkeeps no longer have to manually pump the beer. While this may sound easy, there is a very delicate balance when it comes to carbonation. A beer can look, feel, and, most importantly, taste extremely differently based on the CO2 levels in the beer.
Last but not least, it’s time for nitro. Nitro beer, a combination of nitrogen and oxygen, was created because people wanted the best of both worlds; the smooth, easy-drinking characteristics of hand pull, and the longer shelf life of CO2. The nitro blend was discovered by mathematician Michael Ash, one of the many academics hired by Guinness in the 1950s to encourage innovation in their brewing techniques. Nitrogen will not stay dissolved in liquid unless under pressure, which is what gives the cascading bubble effect when a beer on a nitro tap is poured. It’s cool to watch and gives that delicious beer a smooth, creamy taste.
Now that the mystery is solved, I encourage you to stop by, and stay for a pint of your favorite beer, but in a different serving style than you had the week (or day) before. Better yet, ask the bartender for a side-by-side comparison… you know, for informational purposes.