Tuesday, 24 May 2005 - 11:35 AM

This presentation is part of: Physical Organic

Determining the distribution of an antioxidant between the oil, interfacial and aqueous regions of food-like emulsions stabilized by C12E6

Krishnan Gunaseelan and Laurence S. Romsted. Rutgers University, Piscataway, NJ

We have developed a new approach for estimating the distributions of antioxidants in opaque, surfactant based, macroemulsions based on the pseudophase model for homogenous microemulsions. The distribution of t-butylhydroquinone, TBHQ, in emulsions composed of tributyrin, C12E6, and acidic water is described by two partition constants between the oil and interfacial, POI, and the water and interfacial, PWI, regions. To estimate values for POI and PWI requires fitting two independent data sets with two independent mathematical relations and solving two equations simultaneously. One data set was obtained by electrochemical determination of the observed rate constant, kobs, for reaction of TBHQ with an arenediazonium ion probe as a function of C12E6 volume fraction. The second data set was obtained by determining the partition constant, POW, of TBHQ between tributyrin and water in the absence of surfactant by UV-Visible spectrometry, POW = 0.015. The values of the partition constants in the emulsion are: POI = 11 and PWI = 7.11 x 102. Application of this approach to a variety of antioxidants in emulsions containing different food oils and emulsifiers should provide new insight into the factors controlling antioxidant distributions and may lead to a development of a new scale of antioxidant efficiency.

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