Draught or draft Guinness is special. There is a precise,
elaborate, and time-consuming art-form of pouring the perfect
pint of Guinness beer. Bartenders around the world are given
instructions for the proper pouring process, including details
about the type of glass used, the angle the glass is held at
during the different states of pouring, the precise length of
time the pint must be left to settle, and the force with which
the draught Guinness is poured from the tap.
During the 1950s, Guinness scientist Michael Ash was tasked with
solving the 'draft problem'. At the time, dispensing a draft
pint of Guinness was very complicated, and the company was
losing market share to draft lagers in Britain that could be
easily dispensed with CO2. “The stout was too lively to be
dispensed with CO2 only,” Brady said. “Ash worked on the problem
for four years, working long hours day and night, and became a
bit of a recluse apparently. A lot of doubters at the brewery
called the project ‘daft Guinness'.”
Then Ash attempted
dispensing the beer with plain air. It worked. The secret
ingredient, he discovered, was nitrogen. The air we breathe is
78 percent nitrogen. Today, a Guinness draft contains 75 percent
nitrogen. Not only did the discovery make dispensing the beer
easier, it created a creamy mouthfeel that has been the
signature of Irish stouts since.
Nitrogen forms tighter bubbles than carbon dioxide when put
under pressure in a solution and has a different appearance and
texture. The bubble is a pocket of released gas that becomes
trapped inside of a thin membrane of beer. There are many more
little bubbles in a nitrogen pour.
Incidentally, Draught Guinness, as it is known today, was
first produced in 1964. Bottled Draught Guinness was
formulated in 1978 and launched into the Irish market in 1979.