from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A limonoid found in orange and lemon seeds.
from the GNU version of the Collaborative International Dictionary of English
- n. A bitter, white, crystalline substance found in orange and lemon seeds.
from The Century Dictionary and Cyclopedia
- n. A bitter crystallizable matter (C22H50O13) found in the seeds of oranges, lemons, etc.
This happens because when the juice cells are broken and their contents mixed, acids and enzymes convert a tasteless precursor molecule into an intensely bitter terpene compound called limonin.
Orange juice contains an antioxidant limonin, present in orange juice at about the same levels as vitamin C, that has the unique property of remaining in the blood providing protection for 24 hours, unlike most antioxidants which are gone from the blood after 6 hours.
Sour oranges come from a different species than the kinds described above, and are both sour and bitter thanks not to limonin but a related compound, neohesperidin, with an intense and distinctive peel aroma.
Commercial orange juice is made from juice varieties with little tendency to develop limonin bitterness.
Like navel oranges, grapefruits also contain a precursor of limonin, and its juice becomes bitter on standing.
(In a sense, this plays out within the diminishing returns dilemma concerning limonin, but that is another discussion altogether.)
Department of Agriculture to analyze what parts of the human genome are affected by limonin, a compound found in citrus fruits.
Somasundaram began the research project in 2006 and already conducted cell culture and animal trials using limonin to slow the growth of breast cancer cells.