Enzymatic hydrolysis of arabinoxylans from spelt bran and hull

Spelt bran and hull were submitted to enzymatic treatment during 1 h, 4 h and 24 h to release arabinoxylans (AXs). Several enzymatic commercial preparations with mainly endo-xylanase activity from Trichoderma reesei (Rohalase WL), Thermomyces lanuginosus (Pentopan Mono conc. BG), Bacillus subtilis (Belfeed B MP and Grindamyl Powerbake 900), Humicola insolens (Ultraflo L), Aspergillus aculeatus (Shearzyme 2×), A. aculeatus plus T. reesei (Shearzyme Plus) were tested and combined with a commercial cellulolytic preparation from T. reesei (Celluclast 1.5L). The xylanolytic activity of the commercial enzyme preparations was heterogeneous. The production of monomers by the different enzymes was evaluated on oat spelt xylan. Spelt bran and hull hydrolysates were analysed in regard to their content of total and free sugars. Monomers of glucose were mainly released with Celluclast, Ultraflo L and Shearzyme 2×. The percentage of released AXs ranged from 18.1% to 69.7% for bran and 0.5% to 6.4% for hull (% of the AXs originally present in the substrate). The solution of AXs hydrolysed by endoxylanases from spelt bran contained polysaccharides with a degree of polymerisation (DP) of 2–71 while those hydrolysed with endoxylanases plus Celluclast had DPs were 1–1164. The hydrolysates from spelt hull had much lower DPs (between 2 and 17).

► Enzymatic hydrolysis of arabinoxylans from spelt bran and hull.
► Yields of extraction, degree of polymerisation, content of total and free sugars.
► Commercial enzymatic preparations have great influence on these parameters.
► Yields of extraction were higher for bran than for hull.