An egg protein, lysozyme, is a still unlabeled additive currently used in cheese preparation. Lysozyme is one of the proteins of hens egg white (3.5% of total proteins). Its molecular mass is 14 kDa and its amino acid sequence is entirely known. As it is one of the hens egg allergens, the current allergen nomenclature refers to lysozyme as Gal d 4 (23).