My own reasons. When limes are purely fermented, there will be oil. This is a normal phenomenon. It is caused by the presence of lemon essential oil, citral and a small amount of citronellic acid in the outer peel, which is caused by its own reasons. Lime is also called lemon, green lemon in the literature, and in China it is called lime or lime. It is a collective name for several plants in the genus Rutaceae. Its fruit is characterized by a light yellow-green spherical shape.