Structure and Physical Properties of Plant Wax Crystal Networks and Their Relationship to Oil Binding Capacity

The microstructure, melting and crystallization behavior, rheological properties and oil binding capacity of crystalline networks of plant-derived waxes in edible oil were studied and then compared amongst different wax types. The critical concentrations for oleogelation of canola oil by rice bran wax (RBX), sunflower wax, candelilla wax, and carnauba wax were 1, 1, 2, and 4 %, respectively, suggesting RBX and sunflower wax are more efficient structurants. A phenomenological two-phase exponential decay model was implemented to quantify the oil-binding capacity of these oleogels. Parameters obtained from this empirical model were then evaluated against microscale structural attributes such as crystal size, mass distribution and porosity to determine the structural dependence of oil-binding capacity. Gels containing candelilla wax exhibited the greatest oil-binding capacity, as they retained nearly 90 % of their oil. This is due to the small crystal size as well as the spatial distribution of these crystals. Using a microscopic to macroscopic approach, this study examines how the structural characteristics unique to each wax and resulting oleogel system affect functionality and macroscopic behavior.