Effect of Different Molecular Compositions of Oils on Beeswax-Based Oleogels

Abstract

The molecular compositions of oils affect the properties of oleogels. Current research mainly focuses on the effects of minor components and fatty-acid compositions of triglycerides (TAGs) on the oleogel properties. In this study, the effects of oils with different molecular compositions, including sunflower oil (TAG), medium- and long-chain triglyceride (MLCT), and diacylglycerol (DAG), on the microstructure and physical properties of beeswax (BW) oleogels were investigated. The dielectric constant (ε′) results were higher for DAG (4.21) in comparison with MLCT (3.26) and TAG (3.13), which indicated that DAG had higher polarity. At 5 wt% BW, DAG oleogels had higher oil binding capacity (OBC) (100.00% ± 0.00%) than MLCT (86.54% ± 1.93%) and TAG (77.00% ± 2.00%). Meanwhile, the firmness of DAG oleogel (37.73 ± 3.09 g) was higher than those of MLCT (20.06 ± 0.61 g) and TAG (8.58 ± 0.14 g). Crystallization kinetics results showed that DAG oleogel had the lowest crystallization half-time (0.13 ± 0.01 min) compared to the other two oleogels. The polarized light microscope (PLM) results revealed that all the three BW-based oleogels had the same crystal morphology, and the microstructure of DAG oleogel was denser. Furthermore, obvious intermolecular hydrogen bonds between BW and DAG were observed by Fourier transform infrared (FTIR), which was attributed to the interactions between the hydroxyl groups of DAG and free fatty acids/free fatty alcohols in BW. These results indicated that oils with higher polarity could facilitate the formation of oleogels, making the gel structure more compact and stable.

Practical Application: The higher polarity of DAG and MLCT could enhance the formation of crystal networks of oleogel. This finding could provide further guidance for the preparation of oleogels in the food industry.