A comparison of the flavonol content and composition in dessert, cooking and cider-making apples; distribution within the fruit and effect of juicing

The fruit of all apple varieties tested possessed five quercetin glycosides, namely hyperin, isoquercitrin, reynoutrin, avicularin and quercitrin, as the major flavonol components. Total flavonol levels were in the range 26.4 to 73.9μg/g fresh wt (expressed as aglycone) with hyperin the dominant form in all varieties except Egremont and Jonagored, where quercitrin predominated, and the cider apples, where avicularin predominated. The proportion of flavonol in the peel ranged from 63.0 to 97.1% for the dessert and cooking apples and was not dependent on fruit size. Juice produced from the three varieties of cider apple contained 9.9 to 12.7% of the flavonols with the remainder retained in the pomace.