Foaming of Carbonated Drinks

It is commonly said that shaking a carbonated beverage will cause large amounts of foam to erupt upon opening, and it is often believed that shaking a bottle containing a carbonated beverage will cause the pressure inside to rise. Contrary to this myth, when a pressure gauge is attached to a pressurized bottle of a carbonated beverage, it is found that the pressure within does not increase. It is instead the formation of tiny bubbles from the agitation that causes the foam. Upon opening, the size of the bubbles will rapidly increase due to the reduction in pressure, resulting in excessive foaming.

Agitating carbonated liquid in a resealed vessel increases the rate that CO₂ is released from the solution and the rate that it approaches equilibrium pressure. The equilibrium pressure depends on the temperature, composition, and purity of the liquid, not the agitation of it.