β-glucans and arabinoxylans

Abstract

The major targets in malting and brewing are to obtain maximum extract yield, enough nutrients for yeast growth, fermentable sugars for alcohol production and a balanced combination of high molecular weight compounds to achieve a beautiful and stable foam and smooth mouth feel in beer and to avoid haze formation during storage. Wort and beer filtration difficulties frequently happen in beer processing because of insufficient hydrolysis of cell wall components. It is well documented that insufficient degradation of cell walls hinders the diffusion of germination enzymes, the mobilization of kernel reserves and hence reduces malt extract. β-glucans and arabinoxylans are the major components of endosperm cell walls. In general, insufficient degradation of cell walls is closely related to more residues of these sugars, which may lead to highly viscous wort and beer, giving rise to filtration problems in the brewery. In malt barley breeding, low β-glucan and arabinoxylans contents, or high activities of β-glucanase and xylosidase, which degrade β-glucan and arabinoxylans respectively, have been considered as an important target.