Cooling method impact on wax oleogel properties and oxidative stability: A comparative study between controlled conduction and convection cooling mechanism

Abstract:Wax-based oleogels represent a promising approach for developing functional alternatives to conventional fats. Under quiescent isothermal conditions, waxes form robust space-filling networks that liquid immobilize oil. However, the cooling rate during crystallization significantly influences molecular alignment, crystal growth, and network organization, which collectively determine oleogel properties. Despite this importance, current laboratory-scale cooling methods predominantly rely on coarse convection or conduction/convection mechanisms, such as room-temperature convection or constant incubation temperatures, all lacking precise temperature control. To address this limitation, we developed a novel experimental cooling system (ECS), integrating a thermoelectric cooler with liquid cooling to apply and monitor precise cooling temperature profiles while preparing beeswax oleogels. The oleogels were subjected to three cooling methods: room temperature convection method (RT; 20-26 °C), cold storage conduction/convection method (C; -16°C), and the ECS controlled conduction (2 °C/min of cooling rate). Microstructure analysis revealed that the ECS method produced oleogels with a high number, crystal size, and projected mass fraction. Further rheology analysis showed that the C and ECS-cooled oleogels displayed a more similar tan_delta trend to commercial fat.
Furthermore, under accelerated oxidative conditions (50°C for 35 days), oleogels prepared using the ECS demonstrated a slower lipid oxidation rate. These findings provide key insights into cooling mechanisms' effect on wax-based oleogel properties, offering guidance for food applications of structured lipids