Kinetic Models of Evaporation and Total Phenolics Degradation during Pomegranate Juice Concentration

Pomegranate juice was concentrated by conventional heating at different temperatures (45, 50, 55, 60, and 65 degrees C), and the effect of temperature on evaporation rate and on thermal degradation of total phenolics was investigated. Concentration kinetics modeling was developed based on thin-layer drying models. The logarithmic model was found to give better predictions than the others. The temperature dependence of the model constants was expressed by polynomial relationships. In addition, a first-order decay model, with an Arrhenius and a polynomial dependency on temperature and water content, respectively, was used to describe the joint influence of temperature and moisture content on the thermal degradation of total phenolics in a concentration process of pomegranate juice.