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, available literature data on pure wax esters is summarized and critically reviewed. The detailed analysis of the pre‐existing data on crystallographic (SAXS) and thermal properties, facilitates the interpretation of subsequently performed experiments: Specific wax esters with different carbon numbers and symmetries were studied as such and in oleogels formed in combination with medium chained triglyceride oil at inclusion levels of 10% (w/w). They were characterized regarding their thermal (differential scanning calorimetry [DSC]) and viscoelastic (oscillatory rheology) behavior. It is found that all observations concerning pure wax esters behave systematically, linking molecular makeup, crystal structure, and behavior. The experimental study of oleogels structured by four different binary mixtures of wax esters revealed that substantial chain length differences induce separate crystallization (CN30 + 36 and CN30 + 42). Mixtures of wax esters with only limited chain length difference (≤ 2 carbon atoms) reconfirmed earlier speculations on mixing behavior and crystal structure. Applying mixtures of wax esters only differing in their position of the ester bond (CN36 [14_22] + CN36 [22_14]) indicated ideal mixing behavior in the solid phase of the gels. Surprisingly, the data revealed that additional thermal events occur at specific mixing ratios, predominantly at 1:1 (w/w). 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.

The non-triglyceride structuring of liquid oils, so-called oleogelation, enables new and more beneficial product designs. Natural waxes have proven to be excellent oleogelators due to their wide availability and low inclusion levels. However, waxes vary greatly in their compositions and contain different proportions of major components: wax esters (WE), fatty acids (FA), fatty alcohols (FaOH), and hydrocarbons (HC). In this study six waxes (bees (BW)-, sunflower (SFW)-, ricebran(RBW), carnauba (CRW)-, candelilla (CLW)-, and sugarcane wax(SCW)) are selected to develop a pairwise assessment regarding the major components. Commercial canola oil, rich in minor and polar components, and medium-chain triglycerides (MCT), as a "clean" saturated solvent, are used to elucidate the effect of solvent type on the gel forming behavior of 10% w/w oleogels. The gels are analyzed rheologically, penetronomically, microscopycally, and by calorimetry. It can be shown that the solubility and presence of polar minor components are crucial factors in oleogelation. Practical applications: Useful areas of application can be found in products with high proportions of saturated and trans fatty acids, a high potential of substitution, and can for instance include bakery-, meat-, culinary-and confectionary products.

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.

Wax esters are considered to have a dominant contribution in the gelling properties of wax-based oleogels. To understand their gelling behavior, oleogels of seven different wax esters (total carbon number from 30 to 46; c = 10% [m/m]) in medium-chain triglycerides oil were characterized. Scanning electron microscopy revealed that wax esters crystallize in rhombic platelets with a thickness of 80 to 115 monomolecular layers. Bright field microscopy showed that the regularity and face length of the crystals increased with the total carbon number and molecular symmetry of the respective wax ester. Oscillatory rheology was used to characterize the gel rigidity (Gmax*). Here, wax ester oleogels with smaller total carbon numbers yielded higher Gmax* values than those of wax esters with higher total carbon numbers. The gel rigidity (Gmax*) inversely correlated with the crystal face length. Smaller and optically less well-defined platelets promoted higher gel rigidities. In the case of the microstructure of a specific oleogel composition being manipulated by a variation in the cooling rates (0.8; 5; 10 K/min), this relationship persisted. The information compiled in this manuscript further elucidates the crystallization behavior of wax esters in oleogels. This contributes to the understanding of the composition–structure–functionality relationship of wax-based oleogels supporting future food applications.

The effect of dextran’s molecular mass distribution on the sucrose crystal shape was key to this study. Therefore, sucrose crystals were produced by evaporating crystallization experiments using synthetic thick juices in the form of pure sugar syrups containing high (T2000) and low (T40) molecular mass dextran fractions as well as enzymatically decomposed dextran. The combined analysis of molecular mass distributions by size exclusion chromatography and sucrose crystal shapes by static image analysis were used to identify the least harmful reaction products resulting from the enzymatic decomposition of dextran. The combined evaluation of two shape parameters, circularity and width-to-length ratio, has shown that three different shape modifications can be related to the presence of dextran, namely cube-shaped crystals, elongated needle-shaped crystals and agglomerates. In the main, the data indicated that high T2000 contents and generally all T40 dextran contents led to an increased occurrence of agglomerated and occasionally elongated crystals. The latter was especially found for high T2000 dextran contents. In contrast, low T2000 dextran contents predominantly increased the amount of cube-like crystals. The enzymatic decomposition of dextran resulted in a gradual reduction of the molecular mass. It was shown that an insufficient decomposition to broadly distributed low molecular mass dextran fragments, which are realistic to assume for technical cane and beet juices, still dramatically affected the sucrose crystal shape. Once dextran was decomposed to molecules with molecular masses of less than 5 kDa, no dextran-related effects on the sucrose crystal shape were found.