Extraction of phenolic compounds from tomato pomace using choline chloride–based deep eutectic solvents

The objective of this research was to investigate the efficacy of deep eutectic solvents (DESs)to extract polyphenolic compounds from tomato pomace with the assistance of ultrasound. The phytochemical constituents of tomato pomace extracts (TPE) were verified with a combination of high-performance liquid chromatography coupled with diode array detection and tandem mass spectrometry (HPLC-DAD-MS) and FTIR analysis. The extracted phenolic compounds from tomato pomace were quantified by Folin-Ciocalteu method. The predominant components in tomato pomace extracts were phenolic acids and flavanols. Chlorogenic acid was detected as the main phenolic compound in tomato extracts. The redox behavior of tomato pomace extracts was evaluated by means of cyclic voltammetry. Antioxidant activities of the obtained extracts were determined using the DPPH and ABTS scavenging assays. The reduction capacity of the extracts was assessed using ferric reducing power (FRAP) and phosphomolybdenum (PM) assays. extracts with DESs are characterized by the highest level of antioxidant activity. Theoretical study based on quantum chemistry/molecular modeling were performed to confirm the antioxidants capacity of compounds of tomato pomace extracts. Quantum chemical descriptors such as the frontier orbital energies (E HOMO and E LUMO ), the energy gap between E HOMO and E LUMO (ΔE), hardness, and electrophilicity index have been calculated and discussed. Graphical abstract