Determining antioxidant distributions in model food emulsions: development of a new kinetic method based on the pseudophase model in micelles and opaque emulsions

Abstract

The mechanisms of lipid peroxidation and the distributions of antioxidants in emulsions are not fully understood, in a large part because conventional methods for monitoring reactant distributions in solutions of homogeneous surfactant aggregates cannot be used in opaque emulsions. Here we show that a kinetic method based on monitoring the rate of product formation by HPLC for reaction of an arenediazonium ion probe and the antioxidant TBHQ in aqueous micellar solutions of a non-ionic surfactant, C₁2E₆, gives the same values for the distribution constant of TBHQ as more established spectral shift and kinetic methods. The HPLC method also works in octane/C₁2E₆/H₂O emulsions. To our knowledge, this is the first application of a pseudophase model to a real biphasic system. Future work will focus on estimating distribution constants of a variety of antioxidants in emulsions and attempting to establish a scale of antioxidant efficiency from their rate constants in the surfactant film of the emulsions.

Acknowledgements This is publication No. D10535-1-02 from the Center for Advanced Food Technology (CAFT). This research was supported in part by the State of New Jersey, and the New Jersey Agricultural Experiment Station. The Center for Advanced Food Technology is a New Jersey Commission on Science and Technology Center. We are also grateful to the National Science Foundation, grant number CHE-9985774, for partial support of this research and to Dr. Donald Hamm of Best Foods for extremely fruitful initial discussions.