A spore-forming bacterium, Alicyclobacillus acidoterrestris, is often responsible for fruit juices quality degradation. The objective was to study the influence of ultrasounds and combinations with temperature (thermosonication) on A. acidoterrestris spores inactivation in apple juices. Commercially available juice was artificially inoculated with the bacterium (similar to 10(5) CFU/mL). Sonication was carried out in an ultrasonic bath (35 kHz; 120-480 W) at room temperature and at 70, 80, 85, 90 and 95 degrees C for different times. Thermal treatments at the same temperatures were performed as a control. Sonication had no significant effect on A. acidoterrestris spores inactivation. However, when applied at 70 and 80 degrees C, it allowed 1 log-cycle more of inactivation when compared to thermal treatments and at the end of the processes. Ultrasounds at higher temperatures required approximately half of the treatment time to attain the same inactivation that occurred when the thermal processes were applied alone. In thermosonicated juices, spores decreased by 4.8, 4.7 and 5.5 log-cycles (at 85, 90 and 95 degrees C, respectively) after 90, 60 and 20 min.