Inactivation kinetics of tomato juice lipoxygenase by pulsed electric fields

Pulsed electric field (PEF) inactivation models for tomato juice lipoxygenase (LOX) were studied. Tomato juice was treated by PEF with the combinations of electric field strength (0, 10, 15, 20, 30, 35 kV/cm), PEF treatment time (20, 30, 50, 60, 70 mus), and PEF treatment temperature (10, 20, 30, 40, 50 degreesC). The first-order inactivation models, Hulsheger's model, Fermi's model, and the 2nd-order polynomial equation adequately described the LOX inactivation. Calculated D values were 161.0, 112.9, 101.0, and 74.8 mus at 15, 20, 30, and 35 kV/cm, respectively, at 30 degreesC. The activation energy for the inactivation of LOX by PEF was 35.7 kJ/mol. Applied electric field strength was the primary variable for the inactivation of LOX.