Mechanistic insights into the stabilization of sulforaphane mediated by natural alcohol-derived hydrophobic deep eutectic solvents

As a bioactive isothiocyanate found in cruciferous vegetables, sulforaphane (SF) demonstrates poor thermal stability, which substantially restricts its application in functional foods. This work examined ten natural deep eutectic solvents (NADES) for effective stabilization of SF under thermal stress. At 50 °C, HPLC-MS/MS analyses revealed that all NADES formulations significantly enhanced SF stability ( p < 0.05) compared to aqueous solution, with cinnamyl alcohol-fenchyl alcohol (CiFe) and cinnamyl alcohol-menthol (CiMe) showing the strongest protective effect. Thermal degradation kinetics analysis indicated first-order behavior within the 50–100 °C range. After heating, SF retention rates in CiFe and CiMe ranged from 27–71 % and 17–68 %, respectively, which was markedly higher ( p < 0.05) than that in aqueous solution (3 %). The enhanced stability was attributed from molecular interactions including prolonged hydrogen-bonding lifetimes and strengthened van der Waals interactions within NADES-SF supramolecules, as evidenced by FTIR spectroscopy and molecular dynamics simulations. Moreover, in vitro digestion tests demonstrated that CiFe and CiMe retained 60–70 % of SF, significantly surpassing the retention in aqueous solution (42 %). These findings highlight the potential of hydrophobic NADES as effective stabilizers for SF in functional food delivery systems. • Ten hydrophobic natural deep eutectic solvents improve sulforaphane stability. • The solvents maintain sulforaphane stability at high processing temperatures. • Fourier transform infrared and molecular dynamics reveal stabilizing mechanisms. • In vitro digestion retention and bioaccessibility of sulforaphane are improved.