Limonin is a limonoid, and a bitter, white, crystalline substance found in citrus and other plants.

Chemically, it is a member of the class of compounds known as furanolactones.

[1] Limonin and other limonoid compounds contribute to the bitter taste of some citrus food products.

Researchers have proposed removal of limonoids from orange juice and other products (known as "debittering") through the use of polymeric films.

[2] Limonin is under basic research to assess its possible biological properties.