papin's Profile
Citrus fruit Q's
What makes the juice from Navel oranges bitter is limonin and not it being seedless. As soon as a citrus fruit is squeezed, it has no limonin (unless you crush the seeds, which are loaded with the stuff). The limonin comes from a compound called LARL. When LARL comes into contact with the juices of the fruit it gets transformed into the very bitter limonin. The LARL content peaks in the summer and slowly get transformed away as the fruit matures on the tree. As Valencia oranges are longer on the tree, they have less LARL, hence make better juice oranges. Navels are harvested early and make bitter juice. All citrus fruits have LARL (or one of its molecular cousins), so depending when they are harvested their juice may turn bitter.
The long story can be read at flavoralchemy.squarespace.com
