The method comprises providing an egg with a coating agent comprising a coating component on a sheet material, introducing the egg into a closed container, placing the container in water, introducing a dye solution into the container, adding an inorganic and/or organic acid comprising hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, lactic acid, citric acid, tartaric acid, oxalic acid, ascorbic acid, isoascorbic acid, fumaric acid, adipic acid, succinic acid and/or gluconic acid 5-lactone to the container, and placing the container into a container with a liquid. The method comprises providing an egg with a coating agent comprising a coating component on a sheet material, introducing the egg into a closed container, placing the container in water, introducing a dye solution into the container, adding an inorganic and/or organic acid comprising hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, lactic acid, citric acid, tartaric acid, oxalic acid, ascorbic acid, isoascorbic acid, fumaric acid, adipic acid, succinic acid and/or gluconic acid-5-lactone to the container, placing the container into another container with a liquid, and heating the liquid. The heating step is carried out until the egg is cooked. The container is closed with a vapor permeable closure. A surface of the egg is completely provided with the coating agent. The acid has concentration of 2.5-30 mmole/l. The method further comprises adjusting pH value of the mixture in the container to 6 before heating. An independent claim is included for a system for the treatment of eggs.
