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

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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 , vol. 127 , 107510 . https://doi.org/10.1016/j.foodhyd.2022.107510

Title: 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
Author: Ballance, Simon; Lu, Yudong; Zobel, Hanne; Rieder, Anne; Knutsen, Svein Halvor; Dinu, Vlad T.; Christensen, Bjorn E.; Ulset, Ann-Sissel; Schmid, Marius; Maina, Ndegwa; Potthast, Antje; Schiehser, Sonja; Ellis, Peter R.; Harding, Stephen E.
Contributor organization: University of Helsinki
Department of Food and Nutrition
Carbohydrate Chemistry and Enzymology
Grain Technology
Date: 2022-06
Language: eng
Number of pages: 14
Belongs to series: Food Hydrocolloids
ISSN: 0268-005X
DOI: https://doi.org/10.1016/j.foodhyd.2022.107510
URI: http://hdl.handle.net/10138/343677
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 x 10(3) g/mol. The beta-glucan molecules analysed by these methods were primarily in a random coil conformation as evidenced from individual MarkHouwink-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.
Subject: Dietary fibre
Light scattering
Molar mass
Molecules
Aggregates
FIELD-FLOW FRACTIONATION
LIGHT-SCATTERING
GLYCEMIC RESPONSE
AQUEOUS-SOLUTIONS
BLOOD-GLUCOSE
OAT
BARLEY
CHOLESTEROL
(1->3),(1->4)-BETA-D-GLUCANS
MACROMOLECULES
3143 Nutrition
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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