Use of Photochemiluminescence for the Determination of Antioxidant Activities of Carotenoids and Antioxidant Capacities of Selected Tomato Products

The purpose of this study was to compare the antioxidant activity of carotenoids to that of α-tocopherol by using a photochemiluminescence method (PCL). Comparisons to results obtained by using other established methods (α-TEAC, FRAP, DPPH, LPSC) were carried out. A relationship between the chemical structure of carotenoids and their antioxidant activity could be discussed. The number of conjugated double bonds and functional groups had a positive influence. Additionally, the lipophilic antioxidant capacities of selected tomato products were analyzed using PCL and α-TEAC. HPLC was used to identify and quantify contents of carotenoids, tocopherols, and tocotrienols. The raw material fresh tomatoes had the lowest antioxidant effect in both assays due to the lower carotenoid content. Tomato ketchup had the highest AOC in PCL, and tomato puree, in α-TEAC. The antioxidant capacities were mainly dependent on the water content of the samples. Furthermore, a concentration-dependent effect could be observed in both assays.