Impacts of Steam Injection Technology on Volatile Formation and Stripping During Wort Boiling

In the drive to reduce energy usage in brewing, wort boiling remains an urgent target for optimization, as it remains one of the most energy intensive stages of the process. The Pursuit Dynamics (PDX) wort heater operates as an external wort boiler by injecting conditioned steam into wort at supersonic speeds and claims thus to increase the efficiency of heat transfer. When evaluating the efficacy of new wort boiling processes it is important to determine potential effects on wort volatile formation and stripping, to ensure that there are no downstream impacts on finished beer flavors. Here, concentrations of selected wort volatile compounds were analyzed through the boil utilizing either traditional boiling (external wort heater) or the PDX wort heater, during the full-scale manufacture of 3 products (a lager, a stout and an unfermented malt drink). Results indicated that the PDX wort heater had a relatively minor effect upon wort volatile composition, with furfural, 2-phenylethanal 2-phenethyl alcohol and dimethyl sulfide showing similar rates of formation and stripping as compared with the control boil, for the lager and stout worts. The stripping efficiencies of linalool, beta-myrcene, hexanal and n-hexanol were somewhat reduced in the PDX trial brews. However, analysis of the packaged products revealed that, after downstream processing, analytical and sensory flavor differences between standard boil and PDX trial beverages were minimal.