The paper opens with a discussion on the advantages and disadvantages of high gravity brewing and goes on to consider the process itself. Wort gravities between 13 and 18 degrees Plato are used successfully and most breweries maintain the existing mash bill and make up the remainder of the extract with sugar or syrup added to the kettle. Some adjustments may be necessary e.g. brewhouse times and temperatures, hopping rate, fermentation procedures. In practice, brewers dilute at different stages of the process depending on relative fermentation and storage capacity. Treatment of the dilution water is one of the major aspects of high gravity brewing and involves sterilisation and deaeration. Various methods are available for sterilisation including chlorine treatment, boiling, ultraviolet light, ultrafiltration, ozone treatment and chlorine dioxide, and these processes are briefly described. The water may be deaerated by boiling or vacuum deaeration using steam jet ejectors, liquid ring rotary vacuum pumps or reciprocating dry type vacuum pumps. After treatment, the water is carbonated and cooled to prevent air pickup and stored until required. A number of methods are used to control the blending of the beer and water and range from a simple manual control to sophisticated automatic instrumentation.
Keywords: equipment high gravity brewing survey