Oleogels, semi-solid gels made of vegetable oil and structuring agent, were proposed as healthier alternatives to conventional fats due to their high unsaturated fatty acid content, providing an improved nutritional profile while maintaining similar physical and sensory attributes as fats. Low-molecular-weight oil gelators are commonly used in oleogels due to their ability to mimic the texture and functionality of solid fats while maintaining a healthier nutritional profile. While extensive research on mono-acylglycerides and tri-acylglycerides as single oil gelator or in combination with other gelators is available, only little information can be found in the literature on di-acylglycerides (DAG) and its oil structuring performance.\
The current research aims to investigate the dual functionality of DAG as oil structuring agent and as interfacial stabilizer of water-in-oleogel systems. For that, di-stearin (DS) oleogels and water-in-oleogel systems were prepared using various DS concentrations and water/oleogel ratios. DS formed stable oleogels with a minimum concentration of 10 %wt. and stable emulsion gels with a maximum water content of 30 %wt. DS-based emulsion gels with 30 %wt. water showed a significantly higher gel strength compared with oleogels with the same DS concentration. Interestingly, oleogels demonstrated behavior similar to ideally elastic materials characterized by a zero slope in a frequency sweep test, while emulsion gels exhibited a frequency dependent behavior with a slightly positive slope. Both oleogels and the corresponding emulsion gels exhibited typical sol-gel transitions characterized by a cross-over between the storage and loss modulus and thermo-reversible behavior. DS crystallization in oil revealed the formation of large spherulite crystals, whereas water addition and homogenization reduced the crystal size. Moreover, aggregated crystals were found around the wtare/oil interface, implying on the involvement of DS crystals in the interfacial stabilization of the biphasic system. Overall, saturated DAGs can be used as oil structuring agent as well as surface active agent in emulsion gel systems. Such ability can be exploited while developing new food products based on biphasic systems like margarine and mayonnaise.
- Karin Wagner and Maya Davidovich-Pinhas “Di-acylglycerides as oil structuring agents” Food Structure, 36, 100320 (2023).