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Inter-laboratory analysis of cereal beta-glucan extracts of nutritional importance: An evaluation of different methods for determining weight-average molecular weight and molecular weight distribution

Ballance, Simon; Lu, Yudong; Zobel, Hanne; Rieder, Anne; Knutsen, Svein Halvor; Dinu, Vlad T.; Christensen, Bjørn E.; Ulset, Ann Sissel; Schmid, Marius; Maina, Ndegwa; Potthast, Antje; Schiehser, Sonja; Ellis, Peter R.; Harding, Stephen E.

Inter-laboratory analysis of cereal beta-glucan extracts of nutritional importance: An evaluation of different methods for determining weight-average molecular weight and molecular weight distribution Thumbnail


Authors

Simon Ballance

Yudong Lu

Hanne Zobel

Anne Rieder

Svein Halvor Knutsen

Vlad T. Dinu

Bjørn E. Christensen

Ann Sissel Ulset

Marius Schmid

Ndegwa Maina

Antje Potthast

Sonja Schiehser

Peter R. Ellis

Stephen E. Harding



Abstract

In an interlaboratory study we compare different methods to determine the weight-average molecular weight (Mw) and molecular weight distribution of six cereal beta-glucan isolates of nutritional importance. Size-exclusion chromatography (SEC) with multi-angle light scattering (MALS), capillary viscometry, sedimentation velocity analytical ultracentrifugation and one asymmetric flow field-flow fractionation (AF4)-MALS method all yielded similar Mw values for mostly individual chains of dissolved beta-glucan molecules. SEC with post-column calcofluor detection underestimated the Mw of beta-glucan >500 × 103 g/mol. The beta-glucan molecules analysed by these methods were primarily in a random coil conformation as evidenced from individual Mark-Houwink-Kuhn-Sakurada (MHKS) scaling coefficients between 0.5 and 0.6 and Wales-Van Holde ratios between 1.4 and 1.7. In contrast, a second AF4-MALS method yielded much larger Mw values for these same samples indicating the presence and detection of beta-glucan aggregates. Storage of the six beta-glucan solutions in the dark at 4 °C for 4 years revealed them to be stable. This suggests an absence of storage-induced irreversible aggregation phenomena or chain-scission. Shear forces in SEC and the viscometer capillary and hydrostatic pressure in analytical ultracentrifugation probably led to the reversable dissociation of beta-glucan aggregates into molecularly dissolved species. Thus, all these methods yield true weight-average molecular weight values not biased by the presence of aggregates as was the case in one of the AF4 based methods employed.

Citation

Ballance, S., Lu, Y., Zobel, H., Rieder, A., Knutsen, S. H., Dinu, V. T., Christensen, B. E., Ulset, A. S., Schmid, M., Maina, N., Potthast, A., Schiehser, S., Ellis, P. R., & Harding, S. E. (2022). Inter-laboratory analysis of cereal beta-glucan extracts of nutritional importance: An evaluation of different methods for determining weight-average molecular weight and molecular weight distribution. Food Hydrocolloids, 127, Article 107510. https://doi.org/10.1016/j.foodhyd.2022.107510

Journal Article Type Article
Acceptance Date Jan 15, 2022
Online Publication Date Jan 29, 2022
Publication Date 2022-06
Deposit Date May 22, 2025
Publicly Available Date May 27, 2025
Journal Food Hydrocolloids
Print ISSN 0268-005X
Electronic ISSN 1873-7137
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 127
Article Number 107510
DOI https://doi.org/10.1016/j.foodhyd.2022.107510
Keywords Dietary fibre, Light scattering, Molar mass, Molecules, Aggregates
Public URL https://nottingham-repository.worktribe.com/output/7715663
Publisher URL https://www.sciencedirect.com/science/article/pii/S0268005X22000303?via%3Dihub

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Inter-laboratory analysis of cereal beta-glucan extracts of nutritional importance: An evaluation of different methods for determining weight-average molecular weight and molecular weight distribution (4.3 Mb)
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Publisher Licence URL
https://creativecommons.org/licenses/by/4.0/

Copyright Statement
0268-005X/© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).





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