Flavonoid and chlorogenic acid levels in apple fruit: characterisation of variation

Variations in flavonoid and chlorogenic acid levels within fruit, within tr ee, between orchards, between cultivars and among mutants were characterise d and quantified in 'Elstar' and 'Jonagold' apples by reversed-phase high p erformance liquid chromatography (RP-HPLC). The sun-exposed skin of individ ual fruit had much higher cyanidin 3-galactoside (anthocyanin) and querceti n 3-glycoside levels than the shaded skin, while phloridzin, catechins and chlorogenic acid were similar in the skin of both sides. Individual flavono id and chlorogenic acid levels were not equally distributed within the frui t. Quercetin 3-glycosides and anthocyanin were almost exclusively found in the skin. Catechins were mostly found in the skin but some were present in the flesh. Phloridzin was most abundant in the seeds, with intermediate lev els in both the core area and the skin, and the lowest level in the flesh. Chlorogenic acid was mainly present in the core area and the seeds with an intermediate level in the flesh and a low level in the skin. The levels of anthocyanin, quercetin 3-glycosides and total flavonoids were highest in fr uit borne in the top of the tree followed by fruit from the outer tree part s, whereas the lowest levels were found in fruit from the inner Vee. Termin al fruit contained the highest levels of these compounds, including catechi ns, compared to lateral and spur fruit. Phloridzin and chlorogenic acid wer e not affected by the position of the fruit in the tree nor by the bearing wood type. There were large differences in flavonoid and chlorogenic acid l evels in 'Elstar' fruit between two normally productive orchards differing mainly in growth vigour. 'Jonagold' and its mutants had considerably higher levels of flavonoid and chlorogenic acid than 'Elstar' and its mutants. Th e most blushed mutants of both cultivars had higher levels of anthocyanin b ut not of flavonoids or chlorogenic acid compared to the standard cultivar and to the less blushed mutants. The most blushed mutants had a higher numb er of red cells per cell layer and more cell layers containing red cells th an the standard cultivar and the less blushed mutants. (C) 2000 Elsevier Sc ience B.V. All rights reserved.