J. Agric. Food Chem., 51 (22), 6516 -6520, 2003. 10.1021/jf034475w S0021-8561(03)04475-3
Web Release Date: September 30, 2003

Copyright © 2003 American Chemical Society

Major Phenolics in Apple and Their Contribution to the Total Antioxidant Capacity

Ki Won Lee, Young Jun Kim, Dae-Ok Kim,# Hyong Joo Lee, and Chang Yong Lee*#

Department of Food Science and Technology, Cornell University, Geneva, New York 14456; Department of Food Science and Technology, Seoul National University, Seoul 151-742, South Korea; and Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853

Received for review May 7, 2003. Revised manuscript received August 18, 2003. Accepted August 22, 2003. This work was supported in part by a grant from the New York State Apple Research and Development Program and from the BioGreen 21 Program, Rural Development Administration, Republic of Korea.

Abstract:

The contribution of each phytochemical to the total antioxidant capacity of apples was determined. Major phenolic phytochemicals of six apple cultivars were identified and quantified, and their contributions to total antioxidant activity of apples were determined using a 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay and expressed as vitamin C equivalent antioxidant capacity (VCEAC). Average concentrations of major phenolics and vitamin C in six apple cultivars were as follows (mg/100 g of fresh weight of apples): quercetin glycosides, 13.20; procyanidin B2, 9.35; chlorogenic acid, 9.02; epicatechin, 8.65; phloretin glycosides, 5.59; vitamin C, 12.80. A highly linear relationship (r 2 > 0.97) was attained between concentrations and total antioxidant capacity of phenolics and vitamin C. Relative VCEAC values of these compounds were in the order quercetin (3.06) > epicatechin (2.67) > procyanidin B2 (2.36) > phloretin (1.63) > vitamin C (1.00) > chlorogenic acid (0.97). Therefore, the estimated contribution of major phenolics and vitamin C to the total antioxidant capacity of 100 g of fresh apples is as follows: quercetin (40.39 VCEAC) > epicatechin (23.10) > procyanidin B2 (22.07) > vitamin C (12.80) > phloretin (9.11) > chlorogenic acid (8.75). These results indicate that flavonoids such as quercetin, epicatechin, and procyanidin B2 rather than vitamin C contribute significantly to the total antioxidant activity of apples.

Keywords: Apples; free radical; phenolics; vitamin C equivalent antioxidant capacity (VCEAC)

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