Evaluation of hydrophilic and lipophilic antioxidant capacity in Spanish tomato paste: usefulness of front-face total fluorescence signal combined with parafac

Abstract

The hydrophilic and lipophilic antioxidant activities due to the main bioactive components present in Spanish tomato paste samples were studied, using standardized and fuorescent methods. After extraction, phenolic antioxidants (Folin-Ciocalteu method) and total antioxidant activity (TEAC assay) were evaluated, examining diferences between hydrophilic and lipophilic extracts corresponding to diferent samples. Total fuorescence spectra of extracts (excitation-emission matrices, EEMs) were recorded in the front-face mode at two diferent ranges: 210–300 nm/310–390 nm, and 295–350 nm/380– 480 nm, for excitation and emission, respectively, in the hydrophilic extracts. In the lipophilic extracts, the frst range was 230–283 nm/290–340 nm, while the second range was 315–383 nm/390–500 nm for excitation and emission, respectively. EEMs from a set of 22 samples were analyzed by the second-order multivariate technique Parallel Factor Analysis (PARAFAC). Tentative assignation of the diferent components to the various fuorophores of tomato was tried, based on literature. Correlation between the antioxidant activity and score values retrieved for diferent components in PARAFAC model was obtained. The possibility of using EEMs-PARAFAC to evaluate antioxidant activity of hydrophilic and lipophilic compounds in these samples was examined, obtaining good results in accordance with the Folin-Ciocalteu and TEAC assays.