Polyphenol Profiles of French Cider Apple Varieties (Malus domesticasp.)

Abstract

The cortex of 14 French apple varieties (12 cider and 2 juice varieties), one English cider variety, and one dessert apple (i.e., Golden Delicious) were studied for their polyphenol composition. Total polyphenols were assayed by the Folin-Ciocalteu method, and the precise polyphenolic composition (monomeric catechins, proanthocyanidins, hydroxycinnamic acids, and dihydrochalcones) was obtained by HPLC following thiolysis. ESI-MS and ESI-MS/MS analyses showed that chlorogenic acid and p-coumaroylquinic acid were methylated under the conditions of thiolysis. Depending on the variety, the global polyphenol concentration varied from 1 to 7 g per kilogram of fresh cortex. Cider varieties globally showed a higher polyphenol concentration than the dessert apple Golden Delicious, bitter varieties being the more concentrated. The proportion of the polyphenol classes varied greatly from one cultivar to another. For all varieties, procyanidins were always the predominant class. They were mainly constituted of (−)-epicatechin units with a small proportion of (+)-catechin as a terminal unit. The average degree of polymerization ranged between 4.2 and 7.5 depending upon the variety with an exception for the sharp varieties Guillevic and Avrolles which showed significant concentrations of procyanidins with DPn of 40 and 50, respectively. Keywords: Apple; cider; HPLC; thiolysis; mass spectrometry; polyphenols; procyanidins