Polyphenolic Profiles in Eight Apple Cultivars Using High-Performance Liquid Chromatography (HPLC)

TLDR

Apple polyphenols are believed to contribute to human health through diverse antioxidant and other biological activities. This study aimed to profile polyphenolic compounds across eight Ontario apple cultivars and their flesh and peel. Significant cultivar‑ and tissue‑dependent differences were observed, with peels containing higher polyphenol levels than flesh, Red Delicious and Northern Spy showing the greatest concentrations, Empire the lowest, and five major groups—including procyanidins, quercetin glycosides, and dihydroxycinnamic acid esters—identified, along with a novel compound, 3‑hydroxyphloretin 2′‑xyloglucoside, underscoring the diverse polyphenolic composition relevant to health.

Abstract

Polyphenolic compounds of apple may play an important role in physiologic functions related to human health. Different polyphenolics may have varied biological activities including antioxidant activity. The objective of this study was to investigate the profiles of polyphenolic compounds in different apple varieties and different parts of an apple. The total and individual polyphenolics differed significantly among the eight apple cultivars grown in Ontario, and the peels had higher concentrations than the flesh. Among the tested cultivars, Red Delicious and Northern Spy had the highest concentrations and Empire the lowest. Five major polyphenolic groups with a total of 16 identified individual compounds were found, among which the dihydroxycinnamic acid esters, phloretin glycosides, and flavan-3-ols were found in both flesh and peel, whereas quercetin glycosides were almost exclusively found in the peel. Cyanidin 3-galactoside was unique to and found only in red apple peels. In both apple peel and flesh, the predominant group of polyphenolics was the procyanidins, followed by quercetin glycosides in the peel and hydroxycinnamic acid esters in the flesh. 3-Hydroxyphloretin 2'-xyloglucoside was newly identified in apple. The results obtained in this study will further the understanding of the polyphenolic composition of apples and their roles in health-promoting physiological functions.