Lumia (citrus)
A recent genomic analysis of several species commonly called 'lemons' or 'limes' revealed that the various individual lumias have different genetic backgrounds. The 'Hybride Fourny' was found to be an F1 hybrid of a citron- pomelo cross, while the 'Jaffa lemon' was a more complex cross between the two species, perhaps an F2 hybrid. The Pomme d'Adam arose from a citron-micrantha cross, while two other lumias, the ‘Borneo’ and ‘Barum’ lemons, were found to be citron-pomelo-micrantha mixes.
Orange (fruit)
The taste of oranges is determined mainly by the relative ratios of sugars and acids, whereas orange aroma derives from volatile organic compounds, including alcohols, aldehydes, ketones, terpenes, and esters. Bitter limonoid compounds, such as limonin, decrease gradually during development, whereas volatile aroma compounds tend to peak in mid– to late–season development. Taste quality tends to improve later in harvests when there is a higher sugar/acid ratio with less bitterness. As a citrus fruit, the orange is acidic, with pH levels ranging from 2.9 to 4.0.