Effect of Supercritical Carbon Dioxide on the Enzymes Inactivation in Single-Strength Carrot Juice

The inactivation of Pectin Methylesterase (PME), and Peroxidase (POD), in fresh single-strength carrot juice by supercritical carbon dioxide (SCCD) at 40 °C and a CO2/juice ratio (w/w) equal to 3 was investigated. In the range of pressure from 10 to 25 MPa and treatment time from 40 to 110 min, both PME and POD were effectively inactivated significantly. The laboratory inactivation tests were performed by using a semi continuous method with a continuous stream of CO2 fed at constant mass flow rate from the beginning to the end of each experimental test. A semi empirical kinetic model that accounts for a residual equilibrium fraction, , of POD and PME was used to describe satisfactorily the inactivation behavior. Under the above mentioned experimental conditions the pressure dependence of the kinetic constants, , can be described satisfactorily by a constitutive equation that is a linear function of the reduced pressure, , of carbon dioxide. The numerical values of the two model parameters, calculated by fitting the experimental data in terms of dimensionless residual activity measured at the end of each experimental tests are: 0.04035 min-1, 0.10720 for POD and 0.00345min-1, 0.08941 for PME