Rheological and mechanical characterization of curcumin-loaded emulsion-filled gels produced with whey protein isolate and xanthan gum

- Mixed gels filled by curcumin-loaded solid lipid microparticles were produced.
- Lipid microparticles were homogeneously distributed in the gelled matrix.
- Rheological data were affected by type and concentration of lipid microparticles.
- Interactions among surfactants and protein chains influenced rheological data.
- Curcumin encapsulation was advantageous for color stability of filled gels.

Reduction of the lipid content of food without textural loss can be carried out by producing emulsion-filled gels. This study aimed to produce and characterize heat-set mixed protein-polysaccharide (whey protein isolate-WPI and xanthan gum-XG) gels filled with curcumin-loaded solid lipid microparticles (SLM). Curcumin-loaded SLM were produced with babacu (Orbignyia speciosa) oil and triestearin using different surfactant (mixtures of tween 60 and span 80) concentrations. Gels produced with WPI, XG at pH 6.5 were characterized by rheology, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), water holding capacity (WHC) and instrumental colorimetry stability. SEM and CLSM analyses showed particulate gels and SLM homogeneously distributed in the biopolymer matrix. Filled gels showed higher values of WHC than non-filled gels. The type and concentration of SLM in filled gels affected their behavior when submitted to small or large deformations. The interactions among protein and surfactants chains, as well as the porosity of gels, influenced significantly in mechanical and rheological properties. Filled gels were more stable in terms of color than non-filled gel, indicating curcumin encapsulation in SLM was advantageous.