Kinetics of Beta-Carotene Degradation at Temperatures Typical of AIr Drying of Foods

Degradation of β-carotene was studied in a model system at temperatures between 60 and 80°C in order to formulate a kinetic model useful in the optimization of air drying processes. Two previously reported kinetic analyses were used: a first order model and a simplified free radical reaction model. In both cases the models fit the experimental data but neither is entirely satisfactory since the kinetic parameters reflected an initial concentration dependence. This dependence disappeared at high carotene initial concentrations and also when the thickness of the lipid layer was increased either by using a support with a lower specific surface area or by adding a saturated fatty acid. These results indicate that at high concentrations oxygen diffusion becomes a limiting factor. When using food systems, a first order model seemed a better choice for the simulation of the carotene degradation. Results could not be directly related to those of the model system, probably because the model was too simple, and did not contain the pro- and anti-oxidant components naturally occurring in foods.