The Relevance of Different Enzymes for the Hydrolysis of β-glucans in Malting and Mashing

Makoto Kanauchi¹ and Charles W Bamforth^2,3
¹Department of Food Management, Miyagi University, 2-2-1 Hatatate Taihaku-ku Sendai Miyagi, 982-0215 Japan.
² Department of Food Science & Technology, University of California, Davis, CA 95616-8598, USA.
³ Corresponding author. E-mail: cwbamforth@ucdavis.edu

J. Inst. Brew. 114(3), 224–229, 2008 | VIEW ARTICLE

ABSTRACT
β-Glucosidase and to a lesser extent endo-β1-4-glucanase are present in significant quantity in raw barley. These enzymes, as well as endo-β1-3, 1-4-glucanase, endo-β1-3-glucanase and exo- β1-3-glucanase, increase in activity during steeping and germination. Exo-β1-3-glucanase stands apart through its very late development during germination and it may be a limiting enzyme in malts that have not received substantial modification. Three separate exo-glucanases were located in malt and each of them displayed a preference for β1-3 linkages. As the principle product of endo-β1-3, 1-4-glucanase is oligosaccharides with a β1-4 linkage at the non-reducing end (from which end exo enzymes approach the substrate), this is likely to be a second reason (alongside the late development of the enzyme) why such oligosaccharides survive in significant quantities into wort. A third contributing factor may be the sensitivity of the exoglucanasesto ions such as potassium, sodium and magnesium.

Key words:
Barley, endo, exo, glucanase.