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

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 exo-glucanases to ions such as potassium, sodium and magnesium.