As the bottle aging on lees is opened and undergoes disgorgement to remove the dead yeasts and other sediments, champagne receives its dosage, and the bottle is sealed again with a cork stopper. With the abrupt exposure to oxygen, and with the permeability of the cork, champagne will age gaining further in aromas and complexity, but the aging will be faster than if the lees were kept in the champagne. Meanwhile, the sugar contained in the dosage also preserves the wine and makes the Maillard reaction possible.