Abstract
Current research on wax-based oleogels indicates wax esters to be the
key component in many natural waxes. This necessitates understanding the
properties of pure wax esters to unravel the gelling mechanism in
wax-based oleogels. Therefore, wax esters with different carbon numbers
and symmetries were studied and characterized regarding their thermal
(DSC) and viscoelastic (oscillatory rheology) behavior. Pure wax esters
and binary mixtures of wax esters were studied as such and in oleogels
formed in combination with medium chained triglyceride oil at
WE-inclusion levels of 10 % (w/w). Interpretation of the observations
was based on detailed analysis of pre-existing data on crystallographic
(SAXS) and thermal properties. It is found that all observations
concerning single pure WE’s obey a systematic framework linking
molecular make up, crystal structure and behavior. The study on the
gelling of four different binary mixtures of wax esters revealed that
substantial chain length differences do have the expected consequence of
separate crystallization. Mixtures of wax esters with only limited chain
length difference reconfirmed earlier speculations on mixing and crystal
structure. Applying mixtures of wax esters only differing in their
position of the ester bond indicated ideal mixing behavior in the solid
phase of the gels. Actually, the data revealed that despite these
expected observations in both systems, additional thermal events occur
at specific mixing ratios. Their supposed relation to compound formation
certainly needs further confirmation. Rheological analysis confirmed
that sequential crystallization results in highest firmness values for
the systems studied.