title: 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) (φoil= 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.
authors.affiliation: Particle and Interfacial Technology Group, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Gent, Belgium. wahyu.wijaya@ugent.be and Vandemoortele Centre for Lipid Science and Technology, Laboratory of Food Technology and Engineering, Department of Food Safety and Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium. ashok2510@gmail.com.
authors.forename: Wahyu
authors.initials: W
authors.lastname: Wijaya
authors.affiliation: Particle and Interfacial Technology Group, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Gent, Belgium. wahyu.wijaya@ugent.be.
authors.forename: Paul
authors.initials: P
authors.lastname: Van der Meeren
authors.affiliation: Department of Food Science and Technology, Faculty of Agricultural Technology, Bogor Agricultural University, Kampus IPB Darmaga Bogor 1668 PO. Box. 220, Indonesia.
authors.forename: Christofora Hanny
authors.initials: CH
authors.lastname: Wijaya
authors.affiliation: Vandemoortele Centre for Lipid Science and Technology, Laboratory of Food Technology and Engineering, Department of Food Safety and Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium. ashok2510@gmail.com.
authors.forename: Ashok R
authors.identifier: http://orcid.org/0000-0002-3840-2473
authors.initials: AR
authors.lastname: Patel
mesh_terms: D004655:Emulsions / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010368:Pectins / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012212:Rheology; D014783:Viscosity; D000067816:Whey Proteins / Q000737:chemistry*
chemical_list: D004655:Emulsions; D011108:Polymers; D000067816:Whey Proteins; D010368:Pectins