Relationship of fruit color and light exposure to lycopene content and antioxidant properties of tomato

Abstract

Tomato (Lycopersicon esculentum Mill.), a potent source of antioxidants in the diet, is characterized by remarkable genetic biodiversity, especially in fruit size and color. Horticultural practices and breeding efforts hold the potential to enhance antioxidant content in tomato fruit, but which antioxidants are most important? Lycopene content, total phenolic content, and radical scavenging capacity were examined in yellow, orange, red, and black-fruited tomato cultivars using lyophilized samples. Color was generally an accurate indicator of lycopene content, with a yellow cultivar containing less lycopene than red cultivars, and two of three red cultivars containing more than an orange cultivar. However, black cultivars as a group did not contain more lycopene than red. Tomato fruit harvested green-mature and exposed to 24 h light during ripening at 25°C in a growth cabinet had a higher lycopene concentration than green-mature fruit exposed for 8 h. 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid (ABTS) radical scavenging activity did not vary among different colored cultivars, and was no different in stored (2 yr) or freshly prepared lyophilized samples. Total phenolic concentration was higher in orange, red, and black fruited cultivars than in yellow. Total phenolic concentration was lower in lyophilized powder samples of orange, red, and black cultivar fruit stored for 2 yr at -20°C relative to freshly prepared samples. Neither lycopene nor total phenolic concentration was well correlated to antioxidant capacity. Key words: High performance liquid chromatography, photoperiod