Enzymic degradation of water-unextractable cell wall material and arabinoxylans from wheat flour
1993
Gruppen, H. | Kormelink, F.J.M. | Voragen, A.G.J.
Differences were investigated in the enzymic breakdown of water-unextractable cell wall material (WUS) of wheat flour by endoxylanase I (endoI) and endoxylanase III (endoIII) purified from Aspergillus awamori. The degradation by these enzymes of water-extracted and alkali-extracted arabinoxylans was also examined. Both enzymes released in total 90% of the arabinoxylans present in the WUS, without solubilization of glucomannans, (1 leads to 3, 1 leads to 4)-beta-glucans and cellulose. Both poly- and oligosaccharides were released during the incubation. Arabinoxylans with similar arabinose/xylose ratios, obtained from different fractions of the WUS, showed different degrees of degradation. No differences could be observed in enzymic solubilization and degradation between WUS and alkali-extracted arabinoxylans from different wheat cultivars. Compared with endoI, incubation with endoIII resulted in a more rapid solubilization and/or degradation of WUS and extracted arabinoxylans. EndoIII digestion resulted also in a more rapid decrease in the total water-holding capacity of the residual WUS, although, when the water-holding capacity was expressed on a per gram of residual WUS basis, a two-fold increase was observed as a result of enzyme incubation. Application of endoIII in baking trials yielded a 14% increase in loaf volume, together with an improvement in crumb structure and 'break and shred', whereas endoI yielded only a 4% increase of loaf volume with no improvement of other baking characteristics.
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