Thermal degradation kinetics of anthocyanins extracted from juçara (Euterpe edulis Martius) and “Italia” grapes (Vitis vinifera L.), and the effect of heating on the antioxidant capacity

- We described the kinetic behavior of the thermal degradation of anthocyanins.
- Thermal degradation of anthocyanins follows a first-order reaction kinetics.
- Anthocyanins in grape degraded more rapidly than anthocyanins in juçara.
- We characterized thermodynamically the degradation processes.
- Degradation reactions were endothermic and not spontaneous.
- The antioxidant capacity of the anthocyanins were retained post-processing.

The effect of temperature on the degradation of anthocyanins in juçara and “Italia” grape extracts was determined between 50 and 90 °C. For both species, thermal degradation followed a first-order kinetic model. The decimal reduction time decreased with increasing temperature, and dependence on the thermodegradable factor was lower at higher temperatures. The anthocyanins from juçara degraded more slowly than those extracted from “Italia” grapes. The activation enthalpy and free energy of inactivation indicated an endothermic reaction, not spontaneous degradation, whereas the activation entropy suggested that the transition state has less structural freedom than that of the reactants. The antioxidant capacity of the extracts was reduced when subjected to 90 °C heat treatment, however, significant quantities of this bioactive compound still remained.