Occurrence of Arabinoxylo-oligosaccharides and Arabinogalactan Peptides in Beer

Total, reducing end, and free neutral monosaccharide analyses were performed to estimate the arabinoxylan (AX) and arabinogalactan peptide (AGP) contents and AX average degree of polymerization (avDP) and arabinose substitution (avDS) of a series of commercial beers representing different beer styles. The analytical data were related to standard beer parameters. AX content was lowest in alcohol-free and light beers (0.49-0.69 g/L) and highest in strong ales (1.19-1.90 g/L) and German white beers (1.64-1.78 g/L). AX content generally correlated well with the original wort extract value of the beers. A similar trend was observed for AGP content, with overall values of 0.07-0.37 g/L. The AX avDS in the different beers was 0.49-0.66, while the AX avDP varied between 19 and 61, indicating the major fraction of these polysaccharides that ended up in the beers was extensively cleaved and present as arabinoxylo-oligosaccharides. Free xylose, arabinose, galactose, and glucose contents in the beers were 0.02-0.13, 0.02-0.11, 0.01-0.04, and 0.06-15.8 g/L, respectively. For the latter parameters, no correlation with standard beer parameters could be found.