Exploring how changes to the steroidal core alter oleogelation capability in sterol: γ-oryzanol blends

Oleogels based on sterols such as beta-sitosterol blended with the sterol ester gamma-oryzanol are a very interesting class of systems, but there are aspects of their formation and structure that remain elusive. It has previously been shown that a methyl group on the C30 position of the sterol-ester plays an important role in gelation. This work explored the effect that having C30 methyl groups on both the sterol and the sterol-ester had on the gelation process and subsequent gel structure. Lanosterol and saponified gamma-oryzanol (which was synthesized as part of this study) were identified as materials of interest, as both feature a methyl group on the C30 position of their steroidal cores. It was observed that both sterols formed gels when blended with gamma-oryzanol, and also that lanosterol gelled sunflower oil without the addition of gamma-oryzanol. All of these gels were significantly weaker than that formed by beta-sitosterol blended with gamma-oryzanol. To explore why, molecular docking simulations along with AFM and SAXS were used to examine these gels on a broad range of length scales. The results suggest that saponified gamma-oryzanol-gamma-oryzanol gels have a very similar structure to that of beta-sitosterol-gamma-oryzanol gels. Lanosterol-gamma-oryzanol gels and pure lanosterol gel, however, form with a totally different structure facilitated by the head-to-tail stacking motif exhibited by lanosterol. These results give further evidence that relatively slight changes to the molecular structure of gelators can result in significant differences in subsequent gel properties.

Automated summary

This study investigated and compared the differences in gelation process and gel structure of gels with different molecular structures. The results suggest that slight changes in the molecular structure of gelators can result in significant differences in gel properties.