Method
Some canned beers are pressurized by adding liquid nitrogen, which vaporises and expands in volume after the can is sealed, forcing gas and beer into the widget's hollow interior through a tiny hole—the less beer the better for subsequent head quality. In addition, some nitrogen dissolves in the beer which also contains dissolved carbon dioxide. It is important that oxygen be eliminated from any process developed as this can cause flavour deterioration when present.
The presence of dissolved nitrogen allows smaller bubbles to be formed thereby increasing the creaminess of the head. This is because the smaller bubbles need a higher internal pressure to balance the greater surface tension, which is inversely proportional to the radius of the bubbles. Achieving this higher pressure would not be possible with just dissolved carbon dioxide, as the greater solubility of this gas compared to nitrogen would create an unacceptably large head.
When the can is opened, the pressure in the can quickly drops, causing the pressurised gas and beer inside the widget to jet out from the hole. This agitation on the surrounding beer causes a chain reaction of bubble formation throughout the beer. The result, when the can is then poured out, is a surging mixture in the glass of very small gas bubbles and liquid.
This is the case with certain types of draught beer such as draught stouts. In the case of these draught beers, which before dispensing also contain a mixture of dissolved nitrogen and carbon dioxide, the agitation is caused by forcing the beer under pressure through small holes in a restrictor in the tap. The surging mixture gradually settles to produce a very creamy head.
Read more about this topic: Widget (beer)
Famous quotes containing the word method:
“Frankly, I adore your catchy slogan, “Adoption, not Abortion,” although no one has been able to figure out, even with expert counseling, how to use adoption as a method of birth control, or at what time of the month it is most effective.”
—Barbara Ehrenreich (b. 1941)
“in the absence of feet, “a method of conclusions”;
“a knowledge of principles,”
in the curious phenomenon of your occipital horn.”
—Marianne Moore (1887–1972)
“Unlike Descartes, we own and use our beliefs of the moment, even in the midst of philosophizing, until by what is vaguely called scientific method we change them here and there for the better. Within our own total evolving doctrine, we can judge truth as earnestly and absolutely as can be, subject to correction, but that goes without saying.”
—Willard Van Orman Quine (b. 1908)