Nitrogen cans work by using a small amount of liquid nitrogen added just before sealing, which creates pressure inside the can as it vaporizes, often interacting with a special "widget" to produce a smooth, creamy pour and head.
Canned beverages, particularly some beers, use nitrogen to achieve a different texture and appearance compared to standard carbonated drinks. This process relies on the unique properties of nitrogen gas. Unlike carbon dioxide (CO2), nitrogen doesn't dissolve as readily in liquid at standard atmospheric pressure, but it creates smaller bubbles, resulting in a smoother mouthfeel and a denser, longer-lasting head.
The Nitrogen Canning Process
The mechanism behind a nitrogen can is quite clever, involving a simple yet effective addition during the canning line:
- Liquid Nitrogen Addition: A tiny dose of liquid nitrogen is added to the can just before it is sealed. This substance is extremely cold (-196°C or -320°F).
- Vaporization and Pressurization: Once the can is sealed, the liquid nitrogen quickly warms up and turns into nitrogen gas. As stated in the reference, this liquid nitrogen "vaporises and expands in volume after the can is sealed".
- Creating Internal Pressure: This rapid expansion significantly increases the pressure inside the sealed can.
- Interacting with the Widget: Many nitrogenated cans contain a widget. This is a hollow plastic ball (or sometimes integrated into the can's base) with a tiny hole. The increased pressure inside the can forces both gas and beer into the widget's hollow interior through this small opening. The reference highlights that this pressure forces "gas and beer into the widget's hollow interior through a tiny hole".
- Release Mechanism: When you open the can, the pressure inside suddenly drops to atmospheric pressure. The higher pressure trapped inside the widget then forces the nitrogenated beer back out through the tiny hole and into the rest of the can. This turbulent release causes the dissolved nitrogen to come out of solution rapidly, creating the characteristic cascading effect and the creamy head.
The reference also notes the importance of the amount of beer inside the widget for the final result: "the less beer inside the widget the better, for subsequent head quality." This suggests that the void space allows for more effective nitrogen release when opened.
What is a Widget?
A widget is a key component in many nitrogen-canned drinks. It's typically a small, spherical or conical plastic device placed inside the can. Its function is to hold a small amount of nitrogenated beer under pressure, releasing it upon opening to create the desired effect.
| Component | Function |
|---|---|
| Liquid Nitrogen | Added before sealing, vaporizes to create pressure. |
| Can | Seals the pressure created by the nitrogen. |
| Widget | Stores pressurized nitrogenated beer, facilitating controlled release. |
| Tiny Hole | Entry/exit point for beer/gas into/out of the widget. |
Benefits of Nitrogen Canning
Using nitrogen in canned beverages offers several advantages:
- Creamy Texture: Provides a smoother, less fizzy mouthfeel compared to CO2 carbonation.
- Dense Head: Creates a thick, stable, and visually appealing head.
- Flavor Profile: Can soften acidic or bitter flavors, complementing certain beer styles like stouts and ales.
Examples of beverages commonly found in nitrogen cans include certain types of stout, cream ales, and occasionally other drinks like coffee or tea.
In summary, nitrogen cans leverage the pressure created by vaporizing liquid nitrogen to either directly pressurize the can or, more commonly in beers, activate a widget that stores and releases pressurized nitrogenated liquid upon opening, resulting in a signature creamy texture and head.
