High pressure processing and thermosonication of beer: Comparing the energy requirements and Saccharomyces cerevisiae ascospores inactivation with thermal processing and modeling

• Nonthermal HPP and thermosonication achieve higher S. cerevisiae spore inactivation in beer than thermal processing.
• Ascospore inactivation in beer by HPP or thermosonication is nonlinear (Weibull).
• Nonthermal HPP is more effective than thermal pasteurization and requires less energy.
• Nonthermal HPP is a promising technology for pasteurization in the beer industry.

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 °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 °C TS, then 60 °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).