41. Addition of xylanase and beta-gulucanase under optimal conditions improves the filtration efficiency in rye-malt brewing

Hideki Maeda (1), Masaru Kato (1), Thomas Kunz (2), Frank-Jürgen Methner (2), Hiroyuki Moriki (1); (1) Research Laboratories for Alcoholic Beverage Technologies, Kirin Company, Limited, Yokohama, Japan; (2) Institute of Food Technology and Food Chemistry, Technical University of Berlin, Berlin, Germany

Technical Session 12: Filtration
Tuesday, August 16  •  8:15–9:30 a.m.
Plaza Building, Concourse Level, Governor’s Square 14

In brewing science, it is known that arabinoxylan influences wort separation and beer filtration efficiency, as well as beta-glucan. However, compared to beta-glucan, less is known about arabinoxylan. Rye malt, with which beer is brewed in the southern United States and Europe, contains a higher amount of arabinoxylan than barley malt or wheat malt. So, we think rye malt would be a model raw material with which to explore the filtration ability afforded by arabinoxylan. We investigated the possibility of improving wort separation from rye malt using two criteria: (i) by varying the malting condition using xylanase or gibberellic acid spraying; and (ii) by using a selection of polysaccharide-degrading enzymes. We first malted the rye in an 800-g scale plant by varying several experimental conditions such as malting temperature, germination days, target steeping degree, etc. We found that a higher malting temperature (20°C) contributed to a lower beta-glucan content, lower viscosity and higher lautering speed compared to a lower malting temperature (15°C). We sprayed rye kernels with xylanase or gibberellic acid during germination with the same malting conditions. Addition of xylanase during germination increased the lautering speed without altering the amount of beta-glucan or the KI value. The time of addition of gibberellic acid seems to have an influence on its effect. Addition of gibberellic acid at the beginning of germination increased the lautering speed and the KI value, while its addition 24 hr after germination did not alter the amount of beta-glucan, the KI value or the lautering speed. These results show that the addition of xylanase during germination is effective in improving wort separation ability without further modifications, while the addition of gibberellic acid improves filtration at the early stages of germination. Next, we added commercial enzymes, consisting of xylanase and beta-glucanase, at the mashing-in stage. We found that the combination of xylanase and beta-glucanase was the most effective for improving lautering speed. Use of xylanase alone was the next best alternative. From these data it is evident that both beta-glucan and arabinoxylan influenced the effectiveness of filtration. The addition of external xylanase is effective during the process of malting or mashing because of the relative scarcity of internal xylanase under these malting conditions. Our results show that adding both xylanase and beta-glucanase at the mashing-in stage is the best way to maximize filtration ability. Further investigation into the benefits of adding the enzymes during malting in addition to mashing would be a significant next step in improving wort separation in rye malt.

Hideki Maeda received a master’s degree in biotechnology from Tokyo University, Japan, in March 2006. In April 2006, he was employed by Kirin Brewery Company, Ltd., as a member of the quality assurance group at the Shiga plant and was transferred to the brewing group of the same plant in 2008. From 2010 he worked at the Research Laboratories for Brewing, Kirin Brewery Company, Ltd. From September 2013 to August 2015 he studied brewing science at the Technical University of Berlin under Prof. Frank-Jürgen Methner. Since September 2015, he has been working in the Research Laboratories for Alcoholic Beverage Technologies in Kirin Company, Ltd.