How do those N2 widgets work in cans of beers like guineas, tetleys and Old Speckled Hen? Is the N2 in the widget and released when the can opens, or is the N2 in the beer and the widget helps mix and froth the whole thing?
closed as off topic by Nathan Koop♦ Sep 27 '11 at 19:42
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...so, if I understand correctly, the widget contains liquid nitrogen when bottled. After bottling the widget raises in temperature and pressurizes to match the pressure of the can. When the can is opened the can drops in pressure and the nitrogen spews out of the widget, stirring the beer into a nice creamy head.