Beer in a barrel (1) is dispensed via supply line (2) to a dispense tap (3). A light source (5) provided between the barrel (1) and the tap (3) illuminates the beer with light having a wavelength of between 350-500 nanometers in order to cause the beer deliberately to become light-struck. That is to say deliberate irradiation of the beer prior to dispense causes the production of 3-methyl-2-butene-1-thiol (MBT) and this improves the post-dispense flavour stability of the beer since it is no longer liable to change flavour if left in the sun.
