title: Activities of antioxidants are affected by colloidal properties of oil-in-water and water-in-oil emulsions and bulk oils.
abstract: The activity of alpha-tocopherol, Trolox, propyl gallate, gallic acid, methyl carnosoate, and carnosic acid was studied in two oil-in-water (o/w) emulsions, in two water-in-oil (w/o) emulsions, and in bulk oil with and without added emulsifiers. All antioxidants had either moderate or higher activity in bulk oil than in the emulsions. In most emulsions, the most polar antioxidants, propyl gallate and gallic acid, exhibited either prooxidant activity or no antioxidant activity. Methyl carnosoate was the most active antioxidant in w/o emulsions but was less active than Trolox in o/w emulsions. alpha-Tocopherol was less active in bulk oil than in emulsions, but its activity in bulk oil was markedly enhanced by the addition of o/w emulsifiers. Partitioning of antioxidants, hydrogen bonding, interphase transport, surface accessibility, and interaction of emulsifier with antioxidants are considered to be important parameters that determine antioxidant activity in lipid-containing systems.
authors.affiliation: Institute of Human Nutrition and Food Science, University of Kiel, Olshausenstrasse 40, D-24118 Kiel, Germany. kschwarz@foodtech.uni-kiel.de
authors.forename: K
authors.initials: K
authors.lastname: Schwarz
authors.forename: S W
authors.initials: SW
authors.lastname: Huang
authors.forename: J B
authors.initials: JB
authors.lastname: German
authors.forename: B
authors.initials: B
authors.lastname: Tiersch
authors.forename: J
authors.initials: J
authors.lastname: Hartmann
authors.forename: E N
authors.initials: EN
authors.lastname: Frankel
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D003102:Colloids; D003314:Corn Oil / Q000737:chemistry*; D004655:Emulsions; D014867:Water
chemical_list: D000975:Antioxidants; D003102:Colloids; D004655:Emulsions; D014867:Water; D003314:Corn Oil