Characteristic aroma, antioxidant properties, and extraction mechanism of Hemerocallis hydrosol extracted by deep eutectic solvent.

Hemerocallis is valued for its ornamental, nutritional, and medicinal properties, but research on the aroma characteristics and antioxidant properties of Hemerocallis hydrosol is limited. In this work, four deep eutectic solvents (DES) and water were used to extract hydrosols from Hemerocallis. Gas chromatography-olfactory-mass spectrometry analysis and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging assays were performed to investigate the effects of different solvents on the volatile compounds and antioxidant properties of Hemerocallis hydrosols, with the extraction mechanism of DES elucidated through theoretical calculations. The results showed that the hydrosols extracted with the five solvents contained a total of 91 compounds, with DES3 (choline chloride and d-glucose) demonstrating the strongest extraction ability. The concentration of volatile compounds in the hydrosol extracted by DES3 reached 11.567 mg/L, approximately 3.5 times that of the water-extracted hydrosol. The ABTS radical scavenging assay indicated that the antioxidant capacity of the hydrosol extracted with DES3 was the highest, roughly twice that of the water-extracted hydrosol. The odor activity values (OAVs) revealed ten key aromatic compounds, such as eugenol, D-carvone, 1-nitro-2-phenylethane and 2-methoxy-4-vinylphenol. Theoretical calculations suggested that DES3's greater extraction ability resulted from forming more hydrogen bonds and stronger van der Waals interactions with the aromatic compounds.