The composition of edible oils modifies β-sitosterol_γ-oryzanol
oleogels Part I: Purified triglyceride oils
Abstract
The role of solvent composition, in particular, minor oil components on
sterol/sterol ester oleogels, has been studied recently [1].
Reportedly, deterioration products hamper network formation and modify
the gel’s macroscopic properties, probably due to alterations of the
scaffolding elements’ interactions. However, the role of the FA
composition of TAGs has not yet been addressed. In this study, minor oil
components of three vegetable oils with varying degrees of unsaturation
(iodine values) were removed, and the oils were chemically and
physically characterized before and after the treatment. Consequently, β
sitostero/γ-oryzanol oleogels were produced, and the gel-sol (DSC) and
sol-gel (rheology) transitions were monitored. Moreover, large and small
deformation tests were performed, and the results were linked to oil
parameters. In contrast to minor oil components, the FA composition has
little impact on oleogel properties. The decline in gel hardness with IV
is possibly linked to a lower solvent viscosity. However, a considerable
drop in gel-sol transition temperature was observed with increasing IV
indicating fewer elements of scaffolding. That was linked to the rapid
formation of primary oxidation products in purified flaxseed oil during
oleogel preparation, impairing tube formation. Similar to previous
results on deterioration products, these minor components seem to aid
network strength at low concentrations resulting in similar transition
enthalpies and G’. That might be due to shifted network interactions in
the presence of molecular species with functional groups. In the second
part of this study, these modified interactions in the presence of
selected minor components will be discussed.