SOLUBILIZATION OF ARABINOXYLANS FROM ISOLATED WATER-UNEXTRACTABLE PENTOSANS AND WHEAT-FLOUR DOUGHS BY CELL-WALL-DEGRADING ENZYMES

Water-unextractable pentosans (WUP) isolated from the flours of three wheat cultivars (Apollo, Soissons, Thesee) were treated with enzymes t o solubilize the arabinoxylans. The water-unextractable arabinoxylans from the three cultivars had similar susceptibility to solubilization by enzymes: Grindamyl S 100 (GS100), a commercial preparation for baki ng, rich in pentosanase activities that originated from an Aspergillus niger culture; and three endoxylanases (E1, E2, E3), an arabinofurano sidase (Af), a beta-glucanase (beta G), and a ferulate esterase (FAE) purified from GS100. A cellulase (C) and a pure endoglucanase (eG) fro m Trichoderma reesei were also used. GS100 was able to solubilize high molecular weight arabin-oxylans (HMWAX) from WUP that markedly enhanc e the viscosity of the reaction mixture supernatants. The endoxylanase El was responsible for this solubilizing activity of GS100, whereas E 2 and E3 made only a very low contribution. Combining E1 with FAE led to a limited increase in the arabinoxylan-solubilizing effect. Also, e nzymes hydrolyzing cellulose and beta-glucans slightly improved the ar abinoxylan solubilization from WUP when combined with GS100 or E1, but produced arabinoxylans of lower intrinsic viscosity. Similar effects of the enzymes were observed on arabinoxylan solubilization when appli ed to dough instead of isolated WUP.