Colour changes in thermally processed cupuacu (Theobroma grandiflorum) puree:: critical times and kinetics modelling

Colour changes in thermally treated cupuacu (Theobroma grandiflorum) fruit puree were modelled mathematically. Isothermal experiments in the temperature range of 80-115 degrees C were performed and colour was measured by a tristimulus colorimeter. At each temperature total colour difference (TCD*) increased and normalized L* decreased with processing time, both following a power law model. The power of the model was temperature-dependent and described by the Arrhenius law. To estimate the model constants, a one-step non-linear regression was performed on all data. Activation energies of 31 and 36 kJ/mol were determined for TCD* and normalized L*, respectively. These results should prove useful in the design of pasteurization processes which minimize colour changes in cupuacu puree.