title: Cloning and characterization of a Weissella confusa dextransucrase and its application in high fibre baking.
abstract: Wheat bran offers health benefits as a baking ingredient, but is detrimental to bread textural quality. Dextran production by microbial fermentation improves sourdough bread volume and freshness, but extensive acid production during fermentation may negate this effect. Enzymatic production of dextran in wheat bran was tested to determine if dextran-containing bran could be used in baking without disrupting bread texture. The Weissella confusa VTT E-90392 dextransucrase gene was sequenced and His-tagged dextransucrase Wc392-rDSR was produced in Lactococcus lactis. Purified enzyme was characterized using (14)C-sucrose radioisotope and reducing value-based assays, the former yielding K(m) and V(max) values of 14.7 mM and 8.2 μmol/(mg ∙ min), respectively, at the pH optimum of 5.4. The structure and size of in vitro dextran product was similar to dextran produced in vivo. Dextran (8.1% dry weight) was produced in wheat bran in 6 h using Wc392-rDSR. Bran with and without dextran was used in wheat baking at 20% supplementation level. Dextran presence improved bread softness and neutralized bran-induced volume loss, clearly demonstrating the potential of using dextransucrases in bran bioprocessing for use in baking.
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Kajala
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Qiao
authors.initials: Q
authors.lastname: Shi
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Nyyssölä
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Ndegwa Henry
authors.initials: NH
authors.lastname: Maina
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Yaxi
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Kati
authors.initials: K
authors.lastname: Katina
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Tenkanen
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland.
authors.forename: Riikka
authors.initials: R
authors.lastname: Juvonen
mesh_terms: D001939:Bread / Q000382:microbiology; D003911:Dextrans / Q000378:metabolism; D004043:Dietary Fiber / Q000378:metabolism; D005285:Fermentation; D005516:Food Microbiology; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D058836:Weissella / Q000201:enzymology*
chemical_list: D003911:Dextrans; D004043:Dietary Fiber; D005964:Glucosyltransferases; C020025:dextransucrase