ABSTRACT
Bioactive compounds and their relationship with antioxidant activity were determined in three tomato cultivars (Ronaldo, Siena and Copo) during vine ripening. The lycopene, chlorophyll (total, a and b), total phenolic, flavonoid, vitamin C and folate contents, and the antioxidant activity, by the ferric reducing/antioxidant power assay and the beta-carotene lineolate system, were determined in the samples. Tomato ripening involved the breakdown of chlorophylls, accompanied by a continuous increase in the lycopene content. Total phenolics, flavonoids and vitamin C increased significantly during ripening, whereas the folate content fell markedly as tomatoes turned from green to red. The lycopene and flavonoid content was highest in the Copo cultivar, vitamin C and folate highest in Ronaldo, and total phenolics highest in Siena. The antioxidant activity, as measured with the ferric reducing/antioxidant power assay, increased significantly during ripening in all extracts, and showed a positive correlation with the total phenolic and flavonoid contents. However, when measured with the beta-carotene lineolate system, the antioxidant activity decreased significantly during ripening; perhaps due to the antioxidant activity of chlorophylls and the peroxidation activity of vitamin C.
