Development of Salt- and Gastric-Resistant Whey Protein Isolate Stabilized Emulsions in the Presence of Cinnamaldehyde and Application in Salad Dressing

Abstract

Protein-stabilized emulsions tend to be susceptible to droplet aggregation in the presence of high ionic strengths or when exposed to acidic gastric conditions due to a reduction of the electrostatic repulsion between the protein-coated droplets. Previously, we found that incorporating cinnamaldehyde into the oil phase improved the resistance of whey protein isolate (WPI)-stabilized emulsions against aggregation induced by NaCl, KCl and CaCl2. In the current study, we aimed to establish the impact of cinnamaldehyde on the tolerance of WPI-stabilized emulsions to high salt levels during food processing and to gastric conditions. In the absence of cinnamaldehyde, the addition of high levels of monovalent ions (NaCl and KCl) to WPI-emulsions cause appreciable droplet aggregation, with the particle sizes increasing from 150 nm to 413 nm and 906 nm in the presence of NaCl and KCl, respectively. In contrast, in the presence of 30% cinnamaldehyde in the oil phase, the WPI-emulsions remained stable to aggregation and the particle size of emulsions kept within 200 nm over a wide range of salt concentrations (0–2000 mM). Divalent counter-ions promoted droplet aggregation at lower concentrations (≤20 mM) than monovalent ones, which was attributed to ion-binding and ion-bridging effects, but the salt stability of the WPI emulsions was still improved after cinnamaldehyde addition. The incorporation of cinnamaldehyde into the oil phase also improved the resistance of the WPI-coated oil droplets to aggregation in simulated gastric fluids (pH 3.1–3.3). This study provides a novel way of improving the resistance of whey-protein-stabilized emulsions to aggregation at high ionic strengths or under gastric conditions.

WITHDRAWN: Preparation of fucoxanthin nanoemulsion stabilized by natural emulsifiers: fucoidan, sodium caseinate and gum Arabic

“…The larger oil droplets also appear in emulsion stabilized by proteins in high ionic strength or acidic conditions indicating the occurrence of droplet coalescence and therefore a decrease in droplet surface area. In GT, protease breaks down the structure of a protein in the emulsion which contributes to the destabilization of emulsion and direct lipase-oil contact facilitates faster lipolysis [16,49]. The digestion of proteins in the GT begins firstly by gastric protease and about 18% of casein is digested in SGF for 2 hours [50].…”

Structure and stability characterization of pea protein isolate-xylan conjugate-stabilized nanoemulsions prepared using ultrasound homogenization

“…S4 ). It can be concluded that the prepared nanoemulsions are prone to coalescence, creaming, and phase separation triggered by MgCl 2 and FeSO 4 , which could be attributed to ion binding or ion bridging effects induced by these bivalent salt ions [54] .…”

Preparation of Fucoxanthin Nanoemulsion Stabilized by Natural Emulsifiers: Fucoidan, Sodium Caseinate, and Gum Arabic

“…The larger oil droplets also appear in emulsion stabilized by proteins in high ionic strength or acidic conditions indicating the occurrence of droplet coalescence and therefore a decrease in droplet surface area. In GT, protease breaks down the structure of a protein in the emulsion, which contributes to the destabilization of emulsion and direct lipase–oil contact facilitates faster lipolysis [ 14 , 54 ]. The digestion of proteins in the GT begins firstly by gastric protease, and about 18% of casein is digested in SGF for 2 h [ 55 ].…”