Carrot (Daucus carota L.) peroxidase inactivation, phenolic content and physical changes kinetics due to blanching Original Research Article

The kinetics of peroxidase thermal inactivation, total phenolic content degradation, and colour (CIE L∗a∗b∗) and texture changes were studied in a temperature range of 70–90 °C for carrots (Daucus carota L.). Peroxidase inactivation, total phenolic content degradation and the lightness colour (L∗ parameter) change were successfully described by a first-order reaction model. The redness and yellowness colour (a∗ and b∗ parameters, respectively) and texture (firmness and energy parameters) changes presented a fractional conversion kinetic model behavior. The temperature effect was well described by the Arrhenius law. All the blanching conditions recommended to reduce peroxidase inactivation to an acceptable level (90% loss of its original activity) ensured good quality retention. However, to obtain a high quality carrot product a balance must be made between colour and total phenolic content losses. Therefore, blanching at 80 °C for 6 min is suggested as a compromise condition to maximize quality. The overall study indicated that colour is a critical parameter to optimize carrot hot water blanching condition.