The lethality of ultrapasteurization treatments (70 degrees C/1.5 min.) applied at constant temperature (isothermal condition) and at a constantly raising temperature of 2 degrees C/min (non-isothermal condition) in liquid whole egg (LWE) against two strains of Listeria monocytogenes (STCC 5672 and 4032) and one of Listeria innocua has been investigated. Isothermal survival curves up to 71 C were obtained, which followed first-order inactivation kinetics. The obtained D-r values indicated that L innocua was significantly (p < 0.05) more heat resistant than L. monocytogenes strains. Non-significant (p > 0.05) differences were observed among z values (12.4 +/- 0.4 degrees C, 13.1 +/- 0.4 degrees C and 12.2 +/- 0.7 degrees C for L. innocua and L. monocytogenes 5672 and 4032, respectively). Based on obtained D-r and z values, isothermal ultrapasteurization treatment (70 degrees C/1.5 min.) would provide 3.5-, 5.0-, and 6.5-Log(10) cycles of L innocua and L. monocytogenes 5672 and 4032, respectively. Non-isothermal heating lag phase increased the thermotolerance of Listeria species in LWE. The simulated industrial pasteurization treatment for LWE (heating-up phase from 25 to 70 degrees C followed by 1.5 min. at 70 degrees C) would attain 5-Log(10) reductions of L. monocytogenes 5672 and 4032, and 3.7-Log(10) reductions of L. innocua. Therefore, the safety level of industrial ultrapasteurization concerning L monocytogenes could be lower than that estimated with data obtained under isothermal conditions. (C) 2012 Elsevier Ltd. All rights reserved.