Flavonoid composition over fruit development and maturation in American cranberry, Vaccinium macrocarpon Ait.

Proanthocyanidins, flavonols and anthocyanins were quantified in fruit during fruit growth and ripening in the cranberry varieties 'Ben Lear' and 'Stevens'. Concentrations of proanthocyanidins and total flavonols were highest in flower ovaries and earliest fruit development stages. Proanthocyanidins declined rapidly during ovary development and growth and then increased slightly during fruit ripening. Flavonols exhibited a less pronounced decline from levels in flowers and early fruit set stages, and also increased slightly during fruit ripening. Anthocyanin synthesis was initiated after fruit growth ceased and was greatest during fruit ripening. The flavonoid biosynthetic pathway channeled resources largely towards anthocyanins in 'Ben Lear' and towards both anthocyanins and proanthocyanidins in 'Stevens' during fruit ripening. Patterns of change over the fruit development period for levels of the major flavonol glycosides, quercetin-3-galactoside and quercetin-3-arabinofuranoside, were similar for the two varieties. The varieties exhibited differential rates of accumulation of quercetin-3-arabinopyranoside, quercetin-3-rhamnoside, quercetin-3-(6″-benzoyl)-β-galactoside, methoxyquercetin pentoside, and quercetin-3-(6″-coumaroyl)-β-galactoside. Both variety and phenological stage influence the partitioning of the precursor pool in the biosynthetic pathway of flavonoids in cranberry fruit.