Isolation and properties of Aspergillus niger IBT-90 xylanase for bakery.
Xylanase of low molecular weight (K II) was isolated from the fungus Aspergillus niger IBT-90 cultivated in medium with wheat bran. K II was purified by precipitation with ammonium sulphate (20-80% saturation) and gel filtration on Biogel P-10. This enzyme is most active in hydrolysis of birchwood xylan at 50 degrees C and pH 5.5. Xylanase K II has an ability to degrade 1,4-beta-bonds and to debranch substrates. It degrades not only xylans but also cellulose, an important factor for its application in bakery. Ag+, Fe3+ and NBS are strong inhibitors of the enzyme. DTT and Na+ activate xylanase K II by 24 and 13%, respectively. Enzyme K II used as additive to flour improves dough properties, increases the volume of wheat-rye and whole meal bread, and increases the porosity of crumb and the moisture of the final product, consequently extending the shelf life of bread.
Romanowska
Irena
I
Institute of Technical Biochemistry, Technical University of Lodz, Stefanowskiego 4/10, 90-924 Lodz, Poland. irerom@p.lodz.pl
Polak
Jacek
J
Bielecki
Stanisław
S
D000645:Ammonium Sulfate; D001234:Aspergillus niger / Q000201:enzymology*; D001939:Bread; D002482:Cellulose / Q000378:metabolism; D002850:Chromatography, Gel; D004229:Dithiothreitol / Q000494:pharmacology; D043364:Endo-1,4-beta Xylanases / Q000302:isolation & purification* / Q000378:metabolism*; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D005590:Fractional Precipitation; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology; D008970:Molecular Weight; D012834:Silver / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D013696:Temperature; D014990:Xylans / Q000378:metabolism
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D014990:Xylans; D012834:Silver; D002482:Cellulose; D012964:Sodium; D007501:Iron; D043364:Endo-1,4-beta Xylanases; D000645:Ammonium Sulfate; D004229:Dithiothreitol