Whether served in a tap room or in a restaurant, the perfect pour is the result of the combination of careful brewing and well-controlled dispensing. Brewmasters focus tenaciously on the reproduction of their recipes and their brewing conditions in order to produce consistent products. MATHESON works with breweries – large and small – from coast-to-coast – providing gases and gas control equipment for use in the brewing process.
PART ONE – Successful beer delivery at the pouring faucet
For today’s topic, we’ll look at some of the beer dispensing variables that contribute to draught beer quality where the beer meets the consumer: at the pour.
Dissolved gas (CO2) is a normal ingredient in beer and is the result of the brewing process. Gas pressure is added to propel the beer into the glass and to maintain carbonation. Inside the container (keg), on a continuous basis, gas molecules go into, and out of, solution in the beer. This is called equilibrium. If too little or too much gas pressure changes the balance of dissolved gas levels in the beer, we’ve changed the beer!
Importantly, all beers should not be handled the same way. As any beer aficionado will tell you, no two beers are the same. Looking at carbonation alone, CO2 content might be as low as 2g/L (English cask ale) or in excess of 7g/L (hefeweizen, among others). Different brew types (Stouts, Ales, IPAs, Craft Brews, Domestic Lagers, etc.) will be easier to handle if CO2 pressure is delivered in a CO2/N2 blend that is compatible with the CO2 content of the brew type itself.
Equilibrium in the system is affected by temperature (temperature of the beer) and pressure inside the container. The liquid level inside the container is also a factor; and elevation above (or below!) sea level is also a consideration.
As a starting point, draught beer stored at 38 degrees F should be set up at 12psi. If you serve your beer colder, less applied pressure is needed; if served above 38 degrees F, then more pressure will be needed to keep the gas where it belongs: in the beer. If serving at a high elevation about sea level, this also may require more pressure.
The obvious risk is that too much pressure will lead to overcarbonation and cause the beer to foam when dispensed. Too little pressure leads to the opposite.
If a new keg produces normal foam at first, but begins to foam problematically after a few days, you probably have too much CO2 pressure in the keg, which dissolves more CO2 into the beer (overcarbonation). As the keg empties, you will have less beer and more CO2 in the container. Unmitigated, this is another condition that will lead to overcarbonation (foam). Overcarbonation is easier to prevent (by reducing pressure or CO2 percentage) than it is to remedy. Once overcarbonated, the most successful remedy may well be to check system pressure and start a new keg.
How MATHESON Can Help
Successful, effective dispensing of a variety of brew styles – alongside carbonated soft drinks and mixers – is not complicated, especially if you have the right gas partner. The Gas Professionals at MATHESON can guide you to a gas provisioning solution that makes sense, enables the best product, and saves you money, too.
Watch this space for The Perfect Pour: Part Two, where we will discuss mixtures and blends of gases for different types of beer.