Kinetic Modelling of Turmeric Curing Process

Fresh turmeric rhizomes (Curcuma Longa L.) are traditionally cured in water, then sun-dried and processed into a powder for use as a spice. The curing process significantly affects the overall quality of turmeric. In this study, curing was carried out by two different processes: Conventional Curing (CC) and Improved Conventional Curing (ICC) within the temperature range of 80°C -120°C. The textural degradation kinetics of turmeric during the curing process was studied by applying two kinetic models: first-order kinetics and the fractional conversion model. The change in texture during curing followed a first-order Arrhenius model, with activation energies of 46.34 kJ mol-1 and 40.64 kJ mol-1 for CC and ICC, respectively. The reaction rate over the reference temperature range was observed to vary from 0.0098 min−1 to 0.0431 min−1 for CC and from 0.0013 min−1 to 0.0443 min−1 for ICC. It was observed that ICC influences the rate constant (k) and the activation energy (E), both in favour of texture softening. These findings suggest that texture degradation during turmeric curing follows a predominantly first-order kinetic behaviour, and the derived parameters can serve as a useful tool for process optimization and quality control in turmeric processing.