A method of making a pressurized packaged liquid beverage. The method includes filling a container including a one-way valve with a liquid beverage, sealing the container, introducing a volume of gas through the one-way valve after sealing the container, and agitating the liquid beverage inside the sealed container, When the container is opened, the liquid beverage increases in volume and separates into liquid phase and a drinkable foam phase. The method may be carried out in a sealed container including a one-way valve adapted to allow a gas to enter the first container but not exit or a circulatory agitation system according to other embodiments. Thee liquid beverage may include milk, coffee, fruit juice, or mixtures thereof, particularly mixtures of milk and coffee, and may further include a gum. The gas may be nitrous oxide.
