High-intensity Ultrasound as a Tool to Form Water in Oleogels Emulsions Structured by Lipids Oleogelators

This study aims to evaluate the structuration power and physical properties of oleogel emulsions formed by monoglycerides (MG), hardfat (HF), and lecithin (LE), with and without high-intensity ultrasound (HIU). Emulsion gels with and without HIU were prepared in mono-, bi- and ternary gelator blends (10% of the lipid phase) and with different water (W) proportions (W?=?1, 15, or 30%). All samples were analyzed according to their gel/emulsion formation, microstructure, melting behavior, rheology, texture, polymorphism, and oil binding capacity. In mono structured emulsions only MG was able to form structured emulsions that did not flow. Three synergic combinations of oleogels were found: MG:HF, HF:LE, and MG:HF:LE; nevertheless, the only synergic combination found in all water proportions was MG:HF. Sonicated MG:HF emulsions formed more organized and stable water droplets, and with 30 W even achieved similar physical properties as MG:HF oleogel (0 W). A soft structured emulsion was also found for sonicated LE and HF:LE with 30 W. Multicomponent emulsion gels formed by MG, HF, and LE are a good alternative for food applications because they can form different synergic combinations with good physical properties such as hardness (>?1 N), elastic modulus (>?1?×?10⁵ Pa), and oil binding capacity (>?99%), and these properties can be even improved by HIU.

     

Crystallization and Gelation Behavior of Low- and High Melting Waxes in Rice Bran Oil: a Case-Study on Berry Wax and Sunflower Wax

Low-melting berry wax (BEW) has proven to be a good oil gelator with a positive contribution to the consistency and flexibility of the structured oil. Nevertheless, the properties of BEW and the corresponding oleogel have not yet been investigated in-depth. In this research, the difference in crystallization and gelling behavior between sunflower wax (SW), a high melting wax, and BEW, a low-melting wax, in rice bran oil (RBO) was investigated. The difference in melting and crystallization temperatures can be explained by the different chemical composition (long-chain wax esters in SW and short-chain fatty acids in BEW). The heterogeneity in crystal habits (unidirectional platelets versus microcrystalline particles) and polymorphism (orthorhombic versus hexagonal) are responsible for the varying gel strength and hardness of the respective SW- and BEW-oleogels. The microcrystalline BEW particles aligned and reorganized during 1-month storage at 5 °C, which leaded to an increase in the gel strength and hardness of BEW-oleogel. The gelling property of SW-oleogel however did not significantly differ after 4 weeks at 5 °C, despite of the appearance of spherulitic crystalline clusters. The changes in the physical properties of wax-based oleogels during storage time were further explored using differential scanning calorimetry, polarized light microscope, powder X-ray diffraction and rheology.