High internal phase emulsions stabilized solely by whey protein isolate-low methoxyl pectin complexes: effect of pH and polymer concentration

Abstract

In recent years, there has been significant progress in edible emulsion technology especially with respect to creating and stabilizing surfactant-free emulsion systems for food applications. In this paper, we demonstrate the fabrication of high internal phase emulsions (HIPE) (φ = 0.82) stabilized using colloidal complexes of non-gelling biopolymers (at concentrations as low as 0.3 wt%). The colloidal complexes were pre-formed by combining whey protein isolate (WPI) and low-methoxyl pectin (LMP) at three different pH values (i.e. pH 3.5, 4.5, 5.5) and used further for fabricating stable HIPEs. In addition to the effect of pH, the influence of total biopolymer concentration on the formation and properties of HIPEs was also evaluated. Depending on the total concentration of biopolymers used, the WPI-LMP complexes (formed at pH 4.5) showed a Z-average diameter in the range of 250-350 nm. It was found that the formation of HIPEs was strongly influenced by the pH of the colloidal complexes. At a pH close to the isoelectric point of WPI (≈pH 4.8) and WPI-LMP complexes (≈pH 3.4), severe aggregation of colloidal particles occurred, resulting in poor formation and stability of HIPEs. On comparing the stabilization behaviour of the complexes with the uncomplexed protein, it was noticed that the former provided comparatively better stabilization to the HIPEs against coalescence at pH 4.5 and 5.5. Based on the rheological data (low amplitude oscillatory shear rheology and flow measurements), all HIPE samples showed viscoelastic and shear-thinning behaviour. We believe that such viscoelastic gel-like systems could find potential commercial applications in the development of label-friendly novel food products with interesting textures.

Pickering stabilization of thymol through green emulsification using soluble fraction of almond gum – Whey protein isolate nano-complexes

“…However, it has been shown in several studies that relatively stable Pickering oil-in-water emulsions can be created by particles with values around 60° (C. Li et al, 2013;Wijaya, Van der Meeren, Wijaya, & Patel, 2017). Thymol oil-in-water emulsions stabilized by only WPI showed a rapid phase separation after a few hours of storage at pH 4.5, but the emulsions containing nano-complexes were opaque and homogeneously dispersed (data not shown).…”

A review of the rheological properties of dilute and concentrated food emulsions

“…Rheological measurements can also be used to monitor changes in the structural organization and interactions of the droplet in emulsions. For instance, measuring changes in the viscosity or elastic modulus of an emulsion when system conditions are changed in a specified way can be used to follow changes in emulsion properties (Zhu, Chen, McClements, Zou, & Liu, , ), such as droplet flocculation, continuous phase gelation, or gravitational separation (Wang & Heuzey, ; Wijaya, Van der Meeren, Wijaya, & Patel, ; Wu & McClements, ). This type of measurement can also be used to monitor the degradation of emulsions during preparation or storage.…”

Perspective on oleogelator mixtures, structure design and behaviour towards digestibility of oleogels

“…Usually, protein-polysaccharide complexation is used to stiff the interface of concentrated oil-in-water emulsions (high internal phase emulsion-HIPE). Pairs of soy protein: k-carrageenan [19 ]; whey protein isolate-low methoxyl pectin [20] or even the triad gelatin, tannic acid, and flaxseed gum [21] complexes have been applied for HIPE stabilization. Apart from complexation mechanism, other approaches have been used such as cross-linking (i.e.…”