title: Characterization of Chemically and Thermally Treated Oil-in-Water Heteroaggregates and Comparison to Conventional Emulsions.
abstract: Heteroaggregated oil-in-water (O/W) emulsions formed by targeted combination of oppositely charged emulsion droplets were proposed to be used for the modulation of physical properties of food systems, ideally achieving the formation of a particulate 3-dimensional network at comparably low-fat content. In this study, rheological properties of Quillaja saponins (QS), sugar beet pectin (SBP), and whey protein isolate (WPI) stabilized conventional and heteroaggregated O/W emulsions at oil contents of 10% to 60% (w/w) were investigated. Selected systems having an oil content of 30% (w/w) and different particle sizes (d43≤ 1.1 or ≥16.7 μm) were additionally subjected to chemical (genipin or glutaraldehyde) and thermal treatments, aiming to increase network stability. Subsequently, their rheological properties and stability were assessed. Yield stresses (τ0) of both conventional and heteroaggregated O/W emulsions were found to depend on emulsifier type, oil content, and initial droplet size. For conventional emulsions, high yield stresses were only observed for SBP-based emulsions (τ0,SBPapproximately 157 Pa). Highest yield stresses of heteroaggregates were observed when using small droplets stabilized by SBP/WPI (approximately 15.4 Pa), being higher than those of QS/WPI (approximately 1.6 Pa). Subsequent treatments led to significant alterations in rheological properties for SBP/WPI systems, with yield stresses increasing 29-fold (glutaraldehyde) and 2-fold (thermal treatment) compared to untreated heteroaggregates, thereby surpassing yield stresses of similarly treated conventional SBP emulsions. Genipin-driven treatments proved to be ineffective. Results should be of interest to food manufacturers wishing to design viscoelastic food emulsion based systems at lower oil droplet contents.
authors.affiliation: Dept. of Food Physics and Meat Science, Univ. of Hohenheim, Garbenstrasse 21/25, 70599, Stuttgart, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Maier
authors.affiliation: Dept. of Food Physics and Meat Science, Univ. of Hohenheim, Garbenstrasse 21/25, 70599, Stuttgart, Germany.
authors.forename: Corina L
authors.initials: CL
authors.lastname: Reichert
authors.affiliation: Dept. of Food Physics and Meat Science, Univ. of Hohenheim, Garbenstrasse 21/25, 70599, Stuttgart, Germany. j.weiss@uni-hohenheim.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D027461:Beta vulgaris / Q000737:chemistry; D045703:Emulsifying Agents / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry*; D005504:Food Analysis; D005524:Food Technology; D005782:Gels; D005976:Glutaral / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D031990:Quillaja / Q000737:chemistry; D012212:Rheology; D012503:Saponins / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D000067816:Whey Proteins / Q000737:chemistry*
chemical_list: D045703:Emulsifying Agents; D004655:Emulsions; D005782:Gels; D012503:Saponins; D000067816:Whey Proteins; D014867:Water; D005976:Glutaral
keywords: emulsion; gel; glutaraldehyde; stability; thermal denaturation