The Effect of Fertilization on Antioxidant Activity and Chemical Composition of Tomato Cultivars ( Lycopersicon esculentum Mill. ). Der Einfluss der Düngung auf die antioxidative Kapazität und die chemische Zusammensetzung von Tomatensorten ( Lycopersicon esculentum Mill. )

Summary

Fruits of three tomato varieties grown in greenhouse in peat irrigated with a complete nutrient solution with electrical conductivity of 2 and 5 mS cm, respectively, were assayed for antioxidant activity, and analysed for concentration of soluble solids, total acidity, dry matter and vitamin C, when green, vine-ripened or post-harvest ripened. The experiment showed significant main effects of year, cultivar, degree of maturity and electrical conductivity on antioxidant activity and chemical composition. Small but significant differences were observed between years, and the same pattern of variation of FRAP (Ferric Reducing Ability of Plasma), dry matter, soluble solids, titratable acidity, and vitamin C was observed within years. The degree of maturity (green versus red) explained 49 % of the variation in the data set. Post-harvest- and vine-ripened tomatoes had higher values of titratable acidity,dry matter, soluble solids, FRAP and ascorbic acid. The difference between cultivars accounted for 31 % of the variation.'Favorita' showed the highest values for antioxidant activity,dry matter, soluble solids, titratable acidity and ascorbic acid, thus dominating the variation. FRAP values and ascorbicacid was connected to cultivar, while dry matter, titratableacidity and soluble solid were connected to the fertilizerlevel. The antioxidant activity was not affected by the concentration of the nutrient solution.