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Main Title: Size-Dependent Variability in Flow and Viscoelastic Behavior of Levan Produced by Gluconobacter albidus TMW 2.1191
Author(s): Hundschell, Christoph
Braun, Andre
Wefers, Daniel
Vogel, Rudi
Jakob, Frank
Type: Article
Abstract: Levan is a fructan-type exopolysaccharide which is produced by many microbes from sucrose via extracellular levansucrases. The hydrocolloid properties of levan depend on its molecular weight, while it is unknown why and to what extent levan is functionally diverse depending on its size. The aim of our study was to gain deeper insight into the size-dependent functional variability of levan. For this purpose, levans of different sizes were produced using the water kefir isolate Gluconobacter albidus TMW 2.1191 and subsequently rheologically characterized. Three levan types could be identified, which are similarly branched, but differ significantly in their molecular size and rheological properties. The smallest levan (<107 Da), produced without adjustment of the pH, exhibited Newton-like flow behavior up to a specific concentration of 25% (w/v). By contrast, larger levans (>108 Da) produced at pH ≥ 4.5 were shear-thinning, and the levan produced at pH 5.0 showed a gel-like behavior at 5% (w/v). A third (intermediate) levan variant was obtained through production in buffers at pH 4.0 and exhibited the properties of a viscoelastic fluid up to concentrations of 15% (w/v). Our study reveals that the rheological properties of levan are determined by its size and polydispersity, rather than by the amount of levan used or the structural composition.
Subject(s): levan
molecular weight
Issue Date: 14-Feb-2020
Date Available: 28-Apr-2020
Language Code: en
DDC Class: 660 Chemische Verfahrenstechnik
Sponsor/Funder: BMEL, 2816IP001, Entwicklung strukturgebender Backzutaten mit Exopolysacchariden
Journal Title: Foods
Publisher: MDPI
Volume: 9
Issue: 2
Article Number: 192
Publisher DOI: 10.3390/foods9020192
EISSN: 2304-8158
TU Affiliation(s): Fak. 3 Prozesswissenschaften » Inst. Lebensmitteltechnologie und Lebensmittelchemie » FG Lebensmitteltechnologie und -materialwissenschaften
Appears in Collections:Technische Universität Berlin » Publications

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