Bioactive compounds, folates and antioxidant properties of tomatoes (Lycopersicum esculentum) during vine ripening.

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.