Non-starch polysaccharides in barley and malt: a mass balance of flour fractionation

Flours from dehusked barley and malt were fractionated to obtain water-insoluble cell wall material for structural studies of cell wall polysaccharides and study of their enzymic degradation. Composition was determined for all the fractions obtained. Mass balances were calculated to quantify losses of water-soluble material and to monitor major changes due to malting of the grain. Both in barley and malt, more than 95 % (w/w) of the flour was recovered after fractionation. In the isolated fractions 80-100 % of the mass could be accounted for by the analysed components. (neutral sugars, proteins, lipids). Main components were starch, protein and nonstarch polysaccharides (nsp). The nsp consisted predominantly of arabinose, xylose and glucose. In barley, most of the non-starch glucose was present as (1 → 3, 1 → 4)(ß- D-glucan (ß-glucan). Small amounts of feruloyl and acetyl groups (less than 0-1 % w/w) were also present. After malting, ß-glucan and water-soluble arabinoxylans were almost totally degraded. Water-insoluble arabinoxylans were partly degraded as indicated by recovery of a large amount of arabinose- and xylose-containing material in the ethanol-soluble fraction from malt.