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.

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The effects of cultivar, on-vine ripening, and year of harvest on the folate content of raw tomatoes were studied. Folate content in hot-break tomato puree (HTP) subjected to pasteurization at different temperatures and its evolution during the shelf life of tomato juice were also investigated. 5-Methyltetrahydrofolate (5-CH(3)-H(4)-folate) was the only folate compound identified in raw tomatoes and HTP, but tetrahydrofolate (H(4)-folate) was 10% of the folate detected in tomato juice. The content of folates in raw tomatoes ranged from 4.1 to 35.3 microg/100 g of fresh weight and was highly influenced by all of the factors studied. No clear trend of folate content with ripening stage was observed. The extractability of 5-CH(3)-H(4)-folate from HTP increased significantly after pasteurization at 98 degrees C for 40 s, but higher temperatures decreased its content. Tomato juice showed folate losses during storage independent of the storage temperature. Folate losses were higher when tomato juice was packed in glass bottles than in Tetra Pak.