The effect of hydrodynamic cavitation on isomerization of hop alpha-acids, wort quality and energy consumption during wort boiling

Abstract

Wort boiling is one of the most energy-intensive steps in beer production because the isomerization of hop alpha-acids (AA) into iso-alpha-acids (IAA) is a time and energy-consuming process. Acceleration of this process by hydrodynamic cavitation (HC), created by a Venturi tube cavitation nozzle, at temperatures below the boiling point, has been tested on a pilot scale. The results show that HC accelerated AA isomerization at all temperatures tested (70–90 °C). The highest HC powered isomerization yield was achieved at 90 °C. However, some quality parameters of the wort were not satisfactory (dimethyl sulphide content, hot break) and therefore the process was extended by a final short boil (10 min). This led to a wort comparable to that obtained after the traditional boiling process (100 °C, 90 min) with a simultaneous 33% energy savings.