Crystallization Behavior and Structural Build-Up of Palm Stearin - Wax Hybrid Fat Blends

Hybrid fat blends have emerged as a promising approach to improve the properties of wax-based oleogels which can be used as healthier alternatives for saturated fat products such as butter and margarine. The application of wax-based oleogels is limited because of their sensitivity to shear and waxy mouthfeel. This research investigates the interaction between waxes and palm stearin in hybrid fat blends. For the oleogels, 150% of the critical gelling concentration of the waxes was used, specifically 6% berry wax (BEW), 1.5% candelilla wax (CLW) and 6% carnauba wax (CRW), all incorporated in rapeseed oil. The concentration of palm stearin (PS) in the reference system (30PS) and the hybrid fat blends was 30% (PS-BEW, PS-CLW, PS-CRW). It was found that the addition of PS to the wax-based oleogels largely affected the properties on the nano- to macroscale. On the nanoscale, the polymorphic transition from α to β of palm stearin was delayed when adding BEW, while it did not change with the other waxes. On microscale, the high melting CRW acted as a seeding template for the palm stearin in PS-CRW, resulting in the formation of fat crystals that were rich in CRW in the center. For PS-BEW and PS-CLW, it was hypothesized that the fat crystals were the result of co-crystallization. All three hybrid fat blends showed improved rigidity and shear sensitivity compared to the PS reference and the wax-based oleogels on a macroscale. These results demonstrate that the interaction between palm stearin and waxes can have a positive effect on the final structure.