Changes in pigment concentrations associated with sunburn browning of five apple cultivars. II. Phenolics

Changes in pigment concentrations associated with sunburn were studied by taking peel disks from the sunburned area (SB-2), the area around the sunburned area (halo), the area around the halo (OH), and the center of the sun-exposed side of non-sunburned (NB) ‘Fuji’, ‘Gala’, ‘Delicious’, ‘Golden Delicious’, and ‘Granny Smith’ apples (Malus domestica Borkh). Idaein concentrations in the red cultivars (i.e. ‘Fuji’, ‘Gala’, and ‘Delicious’) decreased from NB to OH to halo to SB-2. Total quercetin glycosides increased from OH to halo to SB-2 in all cultivars except ‘Delicious.’ Chlorogenic acid (CA) concentrations were typically highest in the SB-2 peel and lowest in NB, except in ‘Granny Smith’ where no CA was detected in any peel type.