Flavonoid and chlorogenic acid changes in skin of 'Elstar' and 'Jonagold' apples during development and ripening

Apple fruits are important dietary sources of potentially healthy phenolics . In two successive seasons, changes in the concentration and amount of ind ividual flavonoids and chlorogenic acid during development and ripening wer e investigated by reversed-phase high performance liquid chromatography (R- P-HPLC), in 'Elstar' and 'Jonagold' apples from the outside and the inside of the tree canopy. 'Jonagold' had a higher concentration and amount of fla vonoids and chlorogenic acid than 'Elstar' during fruit development and rip ening. In both cultivars, the concentration on a dry weight basis of querce tin glycosides, phloridzin and chlorogenic acid was highest early in the se ason, but decreased at different rates during fruit development to reach a steady level during maturation and ripening. Catechins (catechin plus epica techin) concentration showed a similar pattern, but a temporary increase wa s observed in an early stage of development. The concentration of cyanidin 3-galactoside (anthocyanin) was relatively high early in the season, gradua lly decreased to a very low steady level during growth, but started to incr ease near maturation, especially in the outer fruit. On a fruit basis the a mount of quercetin glycosides increased during development and was about tw o times higher in 'Jonagold' compared to 'Elstar', both in outer and inner fruit. These compounds were the most abundant flavonoids in the skin of bot h cultivars and their accumulation showed a strong dependency on fruit posi tion on tree. In contrast, the amount of the second most abundant flavonoid type, catechins, increased during development to a maximum and then showed some decrease by mid season which was independent of fruit position on tre e. The amount of phloridzin increased only early in the season reaching a s teady level during development and ripening, and was independent of fruit p osition on tree. The amount of chlorogenic acid in both cultivars initially increased, but subsequently decreased to reach a low, steady level and was slightly higher in outer than in inner fruit. Although anthocyanin concent ration was relatively high at early stages of development, significant accu mulation on a fruit basis only occurred during maturation and ripening. The accumulation of anthocyanin, similar to that of quercetin glycosides, show ed a strong dependency on fruit position on tree. Remarkably, the differenc e in accumulation of anthocyanin and quercetin glycosides in outer and in i nner fruits had no effect on the accumulation of catechins, phloridzin and chlorogenic acid in these fruits. The results indicate that, in general, th e overall production of total flavonoids and chlorogenic acid in apple skin is completed during fruit development before the onset of maturation. (C) 2001 Elsevier Science B.V. All rights reserved.