title: Effects of pH on the ability of flavonoids to act as Pickering emulsion stabilizers.
abstract: The flavonoids tiliroside, rutin and naringin have been investigated as stabilizers of Pickering oil-in-water (O/W) emulsions. The mean droplet size of tetradecane emulsions was considerably smaller at higher pH, especially for rutin. The solubility of flavonoids in the aqueous phase was 4-6 times higher at pH 8 compared to pH 2 for tiliroside and rutin, although all absolute solubilities remained low (<1 mM). This agreed with a slight increase in surface activity of tiliroside and rutin at the O-W interface at pH 8 compared to pH 2. However, improved emulsion stabilization at higher pH is better explained by the significant increase in ζ-potential of the flavonoid particles to more negative values at pH 8, which will improve particle dispersion and increase the charge on the droplets stabilized by them. A buckwheat tea extract, rich in rutin, was also shown to be an effective stabilizer of sunflower O/W emulsions.
authors.affiliation: School of Food Science and Nutrition, University of Leeds, Leeds, UK.
authors.forename: Zijun
authors.initials: Z
authors.lastname: Luo
authors.forename: Brent S
authors.initials: BS
authors.lastname: Murray
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Ross
authors.forename: Malcolm J W
authors.initials: MJ
authors.lastname: Povey
authors.forename: Michael R A
authors.initials: MR
authors.lastname: Morgan
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Day
mesh_terms: D004655:Emulsions / Q000737:chemistry*; D044950:Flavanones / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal; D008956:Models, Chemical; D010316:Particle Size; D012431:Rutin / Q000737:chemistry; D055672:Static Electricity; D013535:Suspensions
chemical_list: D004655:Emulsions; D044950:Flavanones; D005419:Flavonoids; D013535:Suspensions; C052083:tiliroside; D012431:Rutin; C005274:naringin