Today in 1991, US Patent 4996823 A was issued, an invention of William J. Byrne, assigned to Arthur Guinness Son & Company, for his “Method of Packaging a Beverage and a Package Structure.” Here’s the Abstract:

Method of packaging a beverage and a package structure has a cylindrical tube 1 over an end 3 of which is located a partition 2 having restricted orifice and both are sealed, for example by crimping, to the rim of tube 1. Primary chamber 4 is formed within the tube and secondary chamber 8 is formed between the partition 2 and closure 7 which chambers communicate through orifice 6. Chamber 4 is charged with beverage 11 containing gas in solution and sealed with end wall 12 crimped to the rim 9 of the tube 1. Prior to sealing chamber 9 is dosed with liquid nitrogen or carbon dioxide so that headspace 13 is pressurized. The package adjusts to a state of equilibrium in which beverage flows into the secondary chamber 8 to form headspace 14 therein. Upon opening of the package with pull tag 15 a pressure differential between the headspaces 14 and 13 causes beverage and/or gas in chamber 8 to be ejected through orifice 6 into beverage 11 and thereby gas in solution in the beverage to be liberated and form, or assist in the formation of, a head of froth on the beverage.