In this research, pasteurization of beer by nonthermal high pressure processing (HPP) and thermosonication (TS) were compared with thermal pasteurization. The inactivation of Saccharomyces cerevisiae ascospores in beer was studied and modelled for HPP at 200, 300 and 400 MPa, and for TS at 50, 55 and 60 degrees C with an acoustic energy density of 16.15 W/mL. The energy requirements for equivalent ascospore inactivation by HPP, TS, and thermal processes were compared. For the same processing time, ascospore inactivation was greatest with nonthermal HPP, followed by 60 degrees C TS, then 60 degrees C thermal processing. Nonlinear survival curves which could be described by the Weibull model were observed for both HPP and TS. To achieve a 2.5 log reduction in ascospores, HPP required 77 kJ/L compared with 189 kJ/L for thermal processing and 2612 kJ/L for TS. HPP and thermosonication may be alternatives to thermal beer pasteurization, achieving greater log reductions in S. cerevisiae ascospores with shorter processing times (TS and HPP) or less energy (HPP). (C) 2016 Elsevier Ltd. All rights reserved.