Changes in pigment concentrations associated with sunburn browning of five apple cultivars. I. Chlorophylls and carotenoids

Peel disks were taken 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). Chlorophyll a and b concentrations in SB-2 peels of all five cultivars were generally significantly (P ≤ 0.05) lower than those in the halo, OH and NB peels. Significantly higher concentrations of β-carotene, violaxanthin, and antheraxanthin were observed in ‘Fuji’ and ‘Delicious’ SB-2 peel as compared to OH and NB peels. Lower concentrations of β-carotene and L were observed in ‘Granny Smith’ SB-2 and halo peels than in OH and NB peels, with no differences observed in violaxanthin and antheraxanthin concentrations. The results indicate uniform changes in chlorophyll concentrations as a result of sunburn, while changes in carotenoid concentration are cultivar specific.