"Cut-off" effect of antioxidants and/or probes of variable lipophilicity in microheterogeneous media. (1st September 2016)

• Record Type: Journal Article
• Authors: Aliaga, Carolina; López de Arbina, Amaia; Rezende, Marcos Caroli
• Is Part Of: Food chemistry. Volume 206(2016)
• Page Start: 119
• Page End: 123
• Publication Date: 2016-09-01
• Subjects: Hydrophobicity -- 4-AlkanoyloxyTEMPO -- Micelle -- EPR -- Antioxidant activity -- Ascorbate -- BHT -- α-Tocopherol -- Trolox; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2016.03.024
• Languages: English
• ISSNs: 0308-8146

Abstract

Graphical abstract: Highlights: Activities of 4 antioxidants in micelle were measured with TEMPO derivatives. Hydrophilic (ascorbate, Trolox) and hydrophobic (α-tocopherol, BHT) were evaluated. A "cut-off" effect for C6–C8 chain-length probes was observed for all antioxidants. C6–C8 were most reactive with hydrophobic and least with hydrophilic antioxidants. The "cut-off" effect is due to the "amphiphobic" nature of the TEMPO derivatives. Abstract: The activities of two hydrophilic (ascorbic acid and Trolox) and two hydrophobic (α-tocopherol and BHT) antioxidants were measured by reaction with a series of 4-alkanoyloxyTEMPO radical probes1 in buffered (pH 7), aqueous, micellar solutions of reduced Triton-X 100. In all cases, a cut-off effect was observed, in line with previous observations of the same effect for the partitioning of probe series1 in this medium. These results support an interpretation of the cut-off effect in food emulsions, based on the "amphiphobic" nature of either the antioxidants or probes: competition between two molecular moieties, for the micellar hydrophobic core, tends to expose a reacting fragment differently to a more hydrophilic microenvironment, as the probe or antioxidant hydrophobicity increases.