Characterization of O/W emulgels based on whey protein-alginate-inulin coacervates: Influence of temperature and ultrasound as protein preconditioning process

Abstract

Preconditioning processes in proteins play a crucial role in enhancing their functional properties as surface active agents. Whey protein isolate (WPI, 20 wt%) was preconditioned via temperature (WPI_T, 90 °C) or ultrasound (WPI_US, 20 kHz, 80 % amplitude). FTIR and zeta potential analysis demonstrated the effect of the preconditioning process on the secondary structure and surface properties of WPI. WPI-Alginate:Inulin (AI) complex coacervates (CC_WPI:AI) were formed at pH 3.0 using WPI_T and WPI_US, and the associative electrostatic interactions between WPI-AI led to coacervation yields >90 %, influenced by the preconditioning process employed. Viscoelastic properties outlined a predominantly solid-like behavior (G´ > G"). The CC_WPI:AI system based on WPI_T showed enhanced strength and gel-like structure compared to the WPI_US-based system. Oil-in-water (O/W) emulgels were formed and stabilized with the CC_WPI:AI complexes, exhibiting spherical droplets (93.3-292.8 μm), whereas texture and rheological properties highlighted the formation of gel-like systems. The centrifugation STEP technology was used to evaluate the physical stability of emulgels, WPI_T-based emulgels displayed superior stability against creaming than untreated WPI and WPI_US-based emulgels. These findings provide a basis for developing emulgels with prolonged stability and tunable functional properties, tailoring enhanced viscoelastic and texture attributes to meet specific needs for industrial applications where gel-like properties are pursued.

Keywords: Emulgel; Interfacial activity; Protein:polysaccharide complex.