Comparison of on-vine and post-harvest ripening on antioxidant compounds and antioxidant activities of hydroponically grown cherrytomatoes

Tomato fruits are considered as an excellent source of hydrophilic and lipophilic antioxidants. It is generally believed that on-vine ripened tomatoes are characterized by superior nutritional value comparing to post-harvest ripened fruits. The objective of this study was to elucidate this belief with respect to antioxidant activity of tomatoes. Hydroponically grown cherry type tomatoes Solanum lycopersicum L. var. Chiou were harvested at mature green, breaker and red ripe stages. Tomatoes at breaker stage were post-harvest ripened at room temperature. Total phenols, flavonoids, ascorbic acid, and lycopene content of on-vine and post-harvest ripened tomatoes were estimated. The results suggest that post-harvest ripening reduced total phenols but increased ascorbic acid and lycopene content. Antioxidant activity was evaluated with the use of DPPH, FRAP and ORAC assays. The hydrophilic antioxidant activity (HAA) values depended on the assay. DPPH and ORAC methods showed higher HAA for post-harvest tomatoes but FRAP estimated higher HAA for on-vine ripened fruits. All methods revealed that post-harvest ripened tomatoes exhibited significantly higher lipophilic antioxidant activity (LAA). The findings revealed that post-harvest ripening had contradictory implications to water soluble antioxidants and hence to HAA of tomatoes, while LAA levels due to lycopene accumulation were significantly increased.