How the method of beer dispense influences the served CO2 content and the sensory profile of beer

The CO₂ content of draught beer is usually considered to be a function of the original packaged beer CO₂ content, the dispensing gas, and its pressure. This does not take into account one important parameter, which is the influence of the technique of beer dispense on the eventual CO₂ content of beer in glass. The dispense of beer while minimizing foam creation, dispense in one draught, results in the beer in glass CO₂ content being close to that of the original bottle or keg CO₂ content of beer. For the tasters and lager beer in this study, such dispense technique results in higher carbonation flavor and also a more bitter taste, with more harsh bitterness character. Beer dispensed by one draught also emphasizes if the beer suffers from undesirable diacetyl off-flavor that was added in this study. In contrast, beer dispensed by a three-draught technique that has much in common with the legendary German “seven-minute-pils” provided beer that was considered to be superior in overall flavor. With the three-draught dispense technique, the first draught converted all the beer to foam on dispense, resulting in a substantial reduction in beer CO₂ content. The subsequent two draughts also result in further CO₂ loss, finally presenting a beer with a substantially lower CO₂ content. Lager beer dispensed by this technique was superior in flavor in terms of finer bitterness character and intensity and less emphasis of diacetyl off flavor. A formula was developed to accurately predict the eventual beer CO₂ content as a function of the amount of beer foam produced during dispense. These relationships are important not only for dispense recommendations to bartenders for optimal beer serving but also when preparing samples for degustation.