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.

Stabilization of Emulsion and Butter like Products Containing Essential Fatty Acids Using Kalonji Seeds Extract and Curcuminoids

“…The interaction of antioxidant with emulsifi ers at oil/water interface also infl uences its activity 32 by affecting permeability rate of transfer of oxygen across the interface. The The values given are means of three consecutive experiments standard deviations…”

Proximate compositions, phytochemical constituents, antioxidant activities and phenolic contents of seed and leaves extracts of Egyptian leek (Allium ampeloprasum var. kurrat)

“…However, petroleum ether and hexane extracts of seeds showed significantly (p < 0.05) the lowest values of DPPH radical scavenging activity 24.14 and 25.10%, respectively. The β-carotene bleaching method (coupled oxidation of β-carotene and linoleic acid) estimates the relative ability of antioxidant compounds in the plant extracts to scavenge the radical of linoleic acid peroxide that oxidizes β-carotene in the emulsion phase [37]. Total antioxidant activity of the seeds and leaves extracts as measured by the bleaching of beta-carotene ranged from 35.12 to 91.85%.…”

“…The higher antioxidant activity of methanolic and ethanolic extracts than of petroleum ether and hexane extracts may be due to the presence of higher concentrations of both phenolics and flavonoids (Table 4). In previous works, flavonoids and phenolics have been reported as potent antioxidants in β-carotene-linoleic acid bleaching systems [37]. FRAP assay measures the change in absorbance at 593 nm owing to the formation of a blue colored Fe 2+ tripyridyltriazine compound from colorless oxidized Fe 3+ form by the action of electron donating antioxidants.…”

Effects of Antioxidants and Additional Emulsifiers on the Stability of Emulsified Milk Fat in the Photo/Radical Oxidation System

“…The oxidative stability of lipid particles in O/W emulsions is also influenced by many factors such as the pH, type, and concentration of emulsifiers composing the droplet interface 1 . Because lipid oxidation in O/W emulsions takes place mostly at the interface of the lipid and aqueous phases, the interface characteristics of the dispersed particles can have a large effect on the oxidative stability of oils and fats in O/W emulsions 2,3 .…”