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 fluorescent methods. After extraction, phenolic antioxidants (Folin-Ciocalteu method) and total antioxidant activity (TEAC assay) were evaluated, examining differences between hydrophilic and lipophilic extracts corresponding to different samples. Total fluorescence spectra of extracts (excitation-emission matrices, EEMs) were recorded in the front-face mode at two different 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 first 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 different components to the various fluorophores of tomato was tried, based on literature. Correlation between the antioxidant activity and score values retrieved for different 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.

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“…In addition, another fluorescence index BGF_UV, which refers to the blue/green fluorescence induced by 375 nm UV light, was observed to display a decreasing trend during ripening in the study of Kim et al (2019). The BGF_UV is most likely to be related with flavonoids (Lai et al, 2007;Pardo-Botello et al, 2022), which were reported to increase during ripening in another study where the same tomato species was used (Bhandari & Lee, 2016). Further study is needed to investigate the reason for the occurrence of the blue-green fluorescence induced by red light and verify the changing pattern of the BGF_UV index during tomato ripening.…”

“…(2019). The BGF_UV is most likely to be related with flavonoids (Lai et al., 2007; Pardo‐Botello et al., 2022), which were reported to increase during ripening in another study where the same tomato species was used (Bhandari & Lee, 2016). Further study is needed to investigate the reason for the occurrence of the blue‐green fluorescence induced by red light and verify the changing pattern of the BGF_UV index during tomato ripening.…”