29 - Beer and Arabinoxylan

Abstract

Arabinoxylans are non-starch polysaccharides (NSP) and are found in a number of tissues, primarily in the cell wall of the aleurone layers and the endosperm. Arabinoxylans are comprised of a mixed linkage between arabinose and xylose. The arabinoxylan structure is degraded, in conjunction with β-glucan, by enzymes during the malting process to facilitate a trouble-free breakdown of the main endosperm contents (protein and starch). Low temperature mashing (<50°C) continues the breakdown of these NSP. However, arabinoxylans have been attributed to contribute to filtration problem during brewing and haze formation in beer. There is variation with a grain type as well as between grain types used for brewing, with barley having a high arabinoxylan content compared to sorghum with a low content. Further research is required to gain a more detailed understanding of the genetic control of arabinoxylan as well as the enzyme systems that degrade this NSP to ensure trouble-free brewing and consistent beer quality. Improvements in filtration technology could increase pressure on barley breeders and maltsters breeders to produce low level arabinoxylan barley and malt which could impact on other quality parameters.