Quantitative determination of α-tocopherol distribution in a tributyrin/Brij 30/water model food emulsion

Effects of emulsifier hydrophile–lipophile balance and emulsifier concentration on the distributions of gallic acid, propyl gallate, and α-tocopherol in corn oil emulsions

“…Kinetic data were obtained by employing our derivatization method (azo dye formation) as described in detail elsewhere [33]. This methodology exploits the rapid reaction of ArN þ 2 ions with a suitable coupling agent such as N-(1-naphthyl)ethylenediamine, NED, to yielding an stable azo dye, Scheme 4, that is diluted with a 50:50 (v:v) BuOH/EtOH mixture to yield an optically transparent, homogeneous solution whose absorbance is measured spectrometrically [33][34][35]. Control experiments showed that the absorbance of the azo dye at k ¼ 572nm follows Beeŕs law and is a linear function of the concentration of 16-ArN þ 2 .…”

“…The protocols for applying the pseudophase kinetic model to emulsions have been described in detail [32,33], and only the relevant parts are summarized here. As in pseudophase kinetic models, antioxidants and other reactive components partition themselves among the different regions according to their solubility characteristics and surface activity, which are in turn determined by their chemical structures and polarity.…”

“…We proceeded in a different way [31][32][33][34][35][36]. Rather than focusing in developing analytical methods to measure analyte concentrations in the different regions of the emulsion, we focused in building up methods to determine the partition constants of the antioxidants in the intact emulsion.…”

“…In previous work, we used this methodology to investigate the distribution of a number of antioxidants and to evaluate the relative effects of external parameters (temperature and acidity) on their distribution in the different regions of the food emulsions [31][32][33][34][35][36]. Here, we expand our previous investigations and report on the effects of the emulsifier concentration and of the nature of the emulsifier, characterized by the hydrophile-Lipophile Balance (HLB), on the distribution of three selected antioxidants, gallic acid (GA), propyl gallate (PG), and a-tocoppherol (TOC).…”

Interfacial kinetics in octane based emulsions. Effects of surfactant concentration on the reaction between 16-ArN2+ and octyl and lauryl gallates

“…Details of the method are given elsewhere [31]. The final mixture is homogeneous and optically transparent permitting direct spectrometric measurement of the azo dye absorbance.…”