The Widget StoryGuinness Beer - Patent Information on the Smoothifier
The
Widget StoryDraught Guinness in cans maintains the characteristic creamy head and smooth taste of real Guinness through the use of the innovative in can system. This is commonly called the "widget", as was pioneered by Guinnesss in the late 1980's
The Widget is a small piece of plastic with a minute hole punched into it. The Widget is placed inside the can during the first stage of the packaging process. Guinness spent several years, and tried dozens of prototype widgets before coming up with the right shape, weight and density of plastic found in today's In-Can System.
Once the can is filled with Guinness from the holding vats, it is sealed. Once sealed and chilled, the Guinness inside the can becomes naturally pressurized, and this pressure forces around 1% of the Guinness inside the Widget. The Widget has a small chamber inside which is specifically designed to hold a small amount of Guinness which flows in through a very small opening in the underside of the widget.
When the can is opened, the contents reach normal atmospheric pressure. The 1% of Guinness which is held inside the chamber of the Widget is forced out through the small opening in the Widget as the pressure inside and outside the can equalize. The effects is to produce millions of tiny bubbles which rise to the surface and form the familiar, creamy head
When used in cans of Draught Guinness the Widget creates an exact replication of the process that occurs when Guinness is served from the beer tap at your local public house. Thus you can be sure of enjoying a smooth, creamy pint anywhere. Guinness spent from 1984 - 1988 designing the Widget, with a further 18 months of testing the final prototypes. From concept to final production, £5 million was spent on the project and the first Widget-based canning system was installed in Runcorn, Cheshire. Since its introduction, a number of other brewers have started using widgets, spawning a wave of "take home" draught beers.
Guinness
Beer - Patent Information on the SmoothifierRobert James bobjames@delphi.com posted: "I was doing some patent search work at the Washington library in Chicago the other day and I ran across no. 4,832,968, the U.S. patent for the Guinness in a can stout."
Inventors: Alan J. Forage & William J. Byrne
Assignee: Arthur Guinness Son & Co., Ltd.
The gas pod in the can is blow molded with nitrogen (N).
A laser zaps a hole in the pod. (they experimented with holes between 0.2mm and 2.5mm finding that 0.61 mm as ideal)
Pod is inserted in the bottom of can.
Can is filled with CO2/N supersaturated stout. N is present at 1.5% v/v min up to 3.5% v/v. (FYI, vol/vol is the number of volumes of gas which are dissolved in a unit volume of beverage at 760mm of Hg & 15.6 oC) CO2 is present at between 0.8 and 1.5% v/v.
During filling, foam rises to top of can. This clears the air.
A charge of liquid N is added to the stout
Can is sealed.
As liquid N boils off in can during pasteurization (60 oC for 15-20 min), top of can pressurizes and forces the stout into the pod, thus compressing the ambient pressure N in the pod.
Equilibrium is reached at about 25 psi.
As I interpret the patent, this is what happens when the can is opened:
The can quickly depressurizes to ambient pressure. The pod thus expels the stout contained in it (about 10-15 ml) at high velocity through the orifice. This causes high local strain of the stout at the plane of the orifice. This strain exceeds the cohesive forces holding the gases in solution. As a result, the N/CO2 is liberated from the stout at the plane of the orifice. The millions of tiny N/CO2 bubbles then become the foam head. So contrary to my initial belief, while some of the N gas in the pod escapes directly into the stout, it is actually the "ripping apart" of the stout as it exits the pod which produces the bubbles, hence the creamy head.
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