Development and characterization of a novel, edible oleocolloid made of rice bran wax oleogel and sodium alginate-kappa-carrageenan hydrogel

Even though tropical oils are extensively used in the food industry for their physicochemical characteristics; there are environmental concerns regarding their production. Therefore, suitable alternatives to solid fats are a challenge. This work aims to develop and characterize plant-based oleocolloids with the potential to mimic solid fats. Oleocolloids (OC) were prepared by combining an oleogel (OG) composed of 9 wt% rice bran wax (RBW), monoglycerides (MG, 0-2 wt%), and soybean oil with a hydrogel (HG) formulated with 1 wt% sodium alginate and 0.5 wt% kappa-carrageenan in water. Two OG:HG ratios; 7:3 and 8:2 were prepared and analyzed. Homogeneous and self-standing formulations were selected and characterized in their rheological properties by amplitude sweep tests. The microstructure was assessed using confocal scanning laser microscopy (CSLM) and the solid fat content (SFC) profile through pNMR. Micrographs showed that all samples exhibited HG-in-OG structure since HG droplets were dispersed in the OG phase, and their size decreased upon MG addition, accordingly with its emulsifying capacity. Overall, the elastic modulus (G’) and yield stress (σ*) values of 8:2OC were higher than those of 7:3OC. In 8:2OC, G’ and σ* were enhanced with the increase in MG concentration, suggesting that MG participates in the structuring mechanism of the OC, modifies the microstructure, and imparts superior mechanical strength to this matrix. The SFC remained between 6.5 and 8.5% for all OC at temperatures between 10 and 60°C and then it sharply decreased as the temperature approached the melting point (∼70°C). Significance of the work: Oleogel/hydrogel colloidal mixtures have the potential to act as healthy and sustainable alternatives to conventional solid fats; however limited research has been focused on the food applicability of these matrices. This work demonstrated that the novel plant-based oleocolloids developed hold promise to replace solid fats in high-fat foods while enhancing their nutritional profile.