KINETIC OF COLOUR CHANGE OF AIR DRIED FORTIFIED APPLES WITH VITAMIN E

The kinetics of color changes in dehydrated apples fortified with vitamin E is evaluated starting from the CIE-L*a*b * coordinates, tone (hab*) and chromes (Cab*), during 180 days and storage temperatures of 4, 20 and 30ºC. Due to translucency of samples, the Kubelka–Munk’s theory of multiple light dispersion is applied to reflection spectrum, showing an increment in the adsorption compared with dispersion as much as higher is the temperature and storage time. At 4ºC the color is not a critical parameter for the product, since there are not appreciable changes during the 180 days, as well as with packing type (atmospheric and vacuum). At 20 and 30ºC higher changes in color appear, mainly in vacuum packed samples, its evolution defines different trajectories according to packing type and temperature with a tendency to red ones (> a *), from pale to dark color (< L *) and less pure (< Cab *) due to browning. Kinetic models of orders 0. 1 and 2 are applied to describe color changes, being the 2nd order model the one that better coefficient of regression presents in most of parameters.