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Solubilization of Arabinoxylans from Isolated Water-Unextractable Pentosans and Wheat Flour Doughs by Cell-Wall-Degrading Enzymes¹

¹Presented in part at the AACC 81st Annual Meeting, Baltimore, MD, September 1996. ²Unité de Technologie des Céréales et des Agropolyméres, Institut National de la Recherche Agronomique, 2 place Viala 34060 Montpellier cedex 01, France. ³Laboratoire de Biochimie et Technologie des Glucides, Institut National de la Recherche Agronomique, rue de la Géraudière 44026 Nantes cedex 03, France. ⁴Corresponding author. E-mail: rouau@ensam.inra.fr

Water-unextractable pentosans (WUP) isolated from the flours of three wheat cultivars (Apollo, Soissons, Thésée) were treated with enzymes to 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 baking, rich in pentosanase activities that originated from an Aspergillus niger culture; and three endoxylanases (E1, E2, E3), an arabinofuranosidase (Af), a β- glucanase (βG), and a ferulate esterase (FAE) purified from GS100. A cellulase (C) and a pure endoglucanase (eG) from Trichoderma reesei were also used. GS100 was able to solubilize high molecular weight arabinoxylans (HMWAX) from WUP that markedly enhance the viscosity of the reaction mixture supernatants. The endoxylanase E1 was responsible for this solubilizing activity of GS100, whereas E2 and E3 made only a very low contribution. Combining E1 with FAE led to a limited increase in the arabinoxylan-solubilizing effect. Also, enzymes hydrolyzing cellulose and β-glucans slightly improved the arabinoxylan 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 applied to dough instead of isolated WUP.