Limoncello is mainly produced in Southern Italy, especially in the region around the Gulf of Naples, the Sorrentine Peninsula and the coast of Amalfi, and islands of Procida, Ischia, and Capri.[5][failed verification]
Traditionally, limoncello is made from the zest of Femminello St. Teresa lemons, also known as Sorrento or Sfusato lemons.[2][6] Lemon zest, or peels without the pith, is steeped in rectified spirit until the oil is released. The resulting yellow liquid is then mixed with simple syrup. Varying the sugar-to-water ratio and the temperature affects the clarity, viscosity, and flavor. It has a slightly turbid appearance, which originates from the presence of small (approximately 100 nanometers) essential oil droplets suspended in the drink. Opaque limoncellos are the result of spontaneous emulsification (otherwise known as the ouzo effect) of the sugar syrup and extracted lemon oils.[7]
Commercial production was about 15 million liters in 2003.