Intensification of the Dimethyl Sulfide Precursor Conversion Reaction: A Retrospective Analysis of Pilot-Scale Brewer’s Wort Boiling Experiments Using Hydrodynamic Cavitation

Dimethyl sulfide (DMS), a low-boiling compound generated during barley germination and wort cooking from the conversion of its main precursor S-methylmethionine (SMM), a functional biomolecule, is detrimental to beer flavor. Vigorous and prolonged boiling, a time-consuming and energy-intensive process, is required to decrease the content of SMM and the released free gaseous DMS. The standard model assumed wort temperature and pH as the limiting factors of the SMM conversion reaction. The purpose of this study was to assess the specific effect of hydrodynamic cavitation (HC) on the SMM conversion rate in pilot-scale experiments of brewer’s wort boiling. While the standard model was further validated, for the first time the SMM conversion rate was shown to be significantly affected by HC processes. The SMM half-life was reduced by up to 70% and sensitive to HC regimes. The intensification of the SMM conversion reaction could be attributed to the HC-based generation of hydroxyl radicals. Other wort processes unfolded in compliance with standard specifications, such as the removal of free gaseous DMS, the isomerization of hop alpha-acids, and the change in wort color. Evidence supports HC for a substantial reduction in process time and energy consumption in the brewer’s wort boiling step.