Structural and enzymic changes in germinated barley and rye

Germination of barley and rye grains at 15°C and 56% moisture content resulted in the production of α‐amylase, β‐glucanase, endo‐β‐xylanase and α‐arabinosidase. During germination of rye, enzyme activity increased significantly after the first day, whereas in the case of barley a rapid increase was not observed until after the third or fourth day. Rye varieties produced more xylanase, whereas barley produced more α‐amylase and β‐glucanase. Of the barley samples, germinated Pokko had the highest activities of β‐glucanase, xylanase and α‐amylase, and at 46% moisture content highest degradation of cell walls on the basis of image analysis. Arve had the highest α‐arabinofuranosidase activity. Of the rye samples, Amando produced more xylanase and α‐arabinosidase than Anna. The M_w of barley and rye β‐glucan decreased significantly during germination. In rye samples, residual high molecular weight arabinoxylans were still present after 4 days of germination. The mass average molecular weight (M_w) of this fraction was 3 × 10⁶.