Designing and characterizing multicomponent, plant-based bigels of rice bran wax, gums, and monoglycerides

Abstract

In this study, plant-based, edible water-in-oil biphasic gels (bigels) were developed and characterized. Bigels were composed of a rice bran wax (RBW)/soybean oil oleogel (OG) and a sodium alginate/kappa-carrageenan hydrogel (HG). The addition of monoglycerides (MG, 0–2% w/w) in the OG phase and the effect of OG:HG ratio (0:10, 7:3, 8:2, 10:0) were evaluated through physical, microstructural, thermal, and rheological analyses. All bigels were self-supporting and visually homogeneous, except the 7:3 formulation containing 1 and 2% MG, which showed phase separation. Confocal laser scanning microscopy revealed that MG acted as emulsifiers by reducing the HG particle size. Differential scanning calorimetry measurements showed that RBW and MG crystallized in the OG phase, indicating that both components acted as oleogelators. In line with these results, increasing the MG concentration in the OG phase increased the solid fat content of the bigels. Results from small deformation rheology showed that the rheological properties of the bigels were mainly governed by the OG phase. The mechanical strength (G′) followed the trend 0:10≪8:2–7:3<10:0 and further increased after MG addition. The resistance to permanent deformation followed the opposite trend and increased with the increase in MG concentration. In particular, the 8:2 formulation containing 2% MG best fitted the rheological properties required for commercial semi-solid fats. Consequently, the bigels developed in this study constitute a promising plant-based substitute for semi-solid fats with an improved saturated to unsaturated fatty acid ratio.