Most beers are carbonated with carbon dioxide, and at the time of filling, some of the carbon dioxide dissolves into the beer, and the other part creates a small space with a higher pressure on top of the can. When the can is opened, the internal pressure is released, which, combined with the impact of the pour, causes the carbon dioxide in the beer liquid to escape, and the reticulated proteins in the beer intercept this carbon dioxide and form foam by the surface tension of the liquid.
However, using only carbon dioxide to create foam has negative problems, such as the volume of individual foams will be larger, rather than creamy, fine, foam, and therefore not silky, more like Coke or Sprite foam. In order to obtain smaller bubbles, a higher internal pressure is required to balance the increased surface tension of the liquid, and higher internal pressure in the tank can cause a more powerful gush when the can is opened, for highly soluble carbon dioxide.
In addition to the gushing problem, too much carbon dioxide can also change the taste of beer, and the heavy sourness and the irritation of carbonic acid to the mouth will reduce the quality of the beer, and it will make the drinker's stomach bloated quickly. Many industrial lagers have the problem of using too much carbon dioxide, which is also the direct reason why many people feel that they can't drink beer.