M. KAWASAKI (1), T. Fusa (1), A. Yokoyama (1); (1) Kirin Brewery Company, Limited, Yokohama, Japan

Poster

Wort boiling is the most energy-demanding process in the whole brewhouse operation. Along with the increasing interest in the global warming issue, Kirin Group has been making efforts to mitigate CO₂ emissions throughout our value chain. For example, Kirin Brewing Company invested in process facilities such as a vapor compression system to reduce CO₂ emissions in the brewhouse operation. New equipment like low-pressure boiling systems or the Merlin system have been installed to save energy and associated costs as well. While the energy savings of new boiling technology are significant compared with older systems, the initial capital cost to retrofit or upgrade existing brewhouses across a large brewery network, as well as the cost of depreciation over a long time, are very high. One of the most important objectives of wort boiling is to degrade S-methyl methionine (SMM) into dimethyl sulfide (DMS) and evaporate DMS. Isomerization of alpha-acids, hop flavors control, and imparting palate-fullness to beer through the Maillard reaction are also critical in this process. We focused on the dependence of DMS formation and alpha-acid isomerization processes on the temperature of wort and evaluated a simple two-phase wort boiling procedure that could save steam usage in this process. At the first phase of this process, we raised the temperature of a lautered wort and held it at a certain temperature for long enough to convert SMM to DMS and isomerize alpha-acids before it started to boil. After this first phase, we finally started boiling wort to drive-off DMS and hop-derived off-flavors such as myrcene in the second phase. For our particular brand, which requires 90 min of boiling, we could reduce its boiling time down to 30 min after 60 min of the first holding phase. An evaporation rate of 10% could be reduced to 3% also. This new procedure could reduce about 30% of steam usage with the same DMS level and off-flavor intensity as the conventional method. We also found that other quality issues such as hop aroma profile and palate-fullness could be controlled by the duration of the first phase before wort boiling and timing of hop addition during the whole process. This method could lead to energy savings with no major changes in the existing wort-boiling system.

Makoto Kawasaki received an M.S. degree in chemical engineering from Yokohama National University in 2003. He began his employment with Kirin Brewery Company, Limited in 2003 as an assistant quality assurance manager in Kirin’s Shiga brewery. Since 2007 he has functioned as assistant brewing manager in the Sendai brewery dedicated to the improvement of quality and efficiency in the brewing process. He attended the Master Brewers Program at UC Davis and received a Diploma in Brewing from the Institute of Brewing and Distilling in 2010. Since 2010, he has been working at Kirin’s Technology Development Center in Yokohama to develop and evaluate new technology for further cost reduction and improvement of brewhouse and filtration efficiency.