title: Effect of ultrasound and temperature on tomato peroxidase.
abstract: Tomato peroxidase (POD) was inactivated by heat and ultrasound. Thermal inactivation of tomato POD was performed at temperatures of 63, 64, 65, 66 and 67°C. Thermal inactivation of POD in tomato showed apparent first-order kinetics. E(a) was calculated from the slopes of Arrhenius plot and found as 14.9×10(4) J/mol. The effect of ultrasound on tomato peroxidase inactivation was investigated at 15%, 25%, 40%, 50% and 75% ultrasonic powers for 20-150 s. It was observed that as the ultrasonic power increased, inactivation rate increased. 100% POD inactivation was observed at 50% power for 150 s and at 75% power for 90 s of ultrasonication. Regeneration of POD activity was investigated for the samples exposed to ultrasound at different ultrasonic powers. It was observed that at 15% and 25% ultrasonic powers, residual enzyme activity increased linearly, whereas at powers of 40%, 50% and 75% residual enzyme activity increased nonlinearly. There was no regeneration in the samples which 100% enzyme inactivation obtained by ultrasound. A significant decrease in vitamin C content of tomato extract was observed as a function of temperature and treatment time, whereas ultrasonic treatment had no significant effect on vitamin C content of tomato extract.
authors.affiliation: Department of Food Engineering, Faculty of Engineering, University of Gaziantep, Gaziantep, Turkey.
authors.forename: Songül Sahin
authors.initials: SS
authors.lastname: Ercan
authors.forename: Ciğdem
authors.initials: C
authors.lastname: Soysal
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism; D004789:Enzyme Activation; D007700:Kinetics; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism*; D013696:Temperature; D014465:Ultrasonics
chemical_list: D009195:Peroxidase; D001205:Ascorbic Acid