What is a nitro beer?

Nitrogen dissolves about a hundred times less well in beer than carbon dioxide, so less gas is released from the liquid and the sting on the tongue is reduced.

Carbon dioxide arises during fermentation and stays dissolved in the beer until you open the bottle. Nitrogen is added deliberately and barely dissolves. What does get in comes out again in very small bubbles.

Those small bubbles rise slowly and form a dense layer of foam at the top. In the glass you sometimes see them first sink down along the wall before they rise up in the middle.

A widget is a small plastic part in the can that, when opened, forces beer and gas through a narrow opening.

The can is under pressure and the beer is saturated with gas: carbon dioxide, nitrogen or a mixture of the two. As soon as you pull the tab, the pressure drops and beer with gas shoots out of the widget into the surrounding beer.

The opening in the middle of the widget measures 0.02 to 0.25 centimetres. Tony Carey and Sammy Hildebrand developed the component in 1968 at Guinness in Dublin; from 1988 it came onto the market in cans.

Stout and porter most often come on nitrogen, because a dense head of foam goes well with roasted malt.

The choice is a serving choice, not a recipe choice. The same brewery can bottle the same beer on carbon dioxide and tap it on nitrogen. What changes is the way the gas gets into the glass, not the mash or the hops.

Outside the dark styles you also see nitrogen in pale ales and coffee beers. In the Netherlands it is almost always hospitality-trade keg or can with a widget.

An ordinary bottle cannot be poured on nitrogen at home, because that requires a draught installation with a gas mixture and a restrictor plate.

The foam of a nitro beer arises because the beer is pressed under pressure through very small holes. A tap does that with a plate full of holes, a can with a widget. A crown cap cannot imitate that.

If you want the effect at home, cans with a widget remain the simplest route. We are happy to explain in the shop which cans have that widget.

In the Netherlands the Warenwetbesluit Gereserveerde aanduidingen lays down what beer may be called: a drink obtained after alcoholic fermentation of wort.

The same decree reserves the designations alcohol-free beer for at most 0.1 percent alcohol by volume and low-alcohol beer for more than 0.1 and at most 1.2 percent alcohol by volume. The gas with which a beer is served plays no role in those rules.

Welke informatie verder op de verpakking hoort, staat in Verordening (EU) nr. 1169/2011 over voedselinformatie aan consumenten. Alcohol verkopen wij niet aan iedereen onder de 18 jaar. NIX18.