title: Molecular structure of large-scale extracted β-glucan from barley and oat: Identification of a significantly changed block structure in a high β-glucan barley mutant.
abstract: Health effects of β-glucan are typically related to dose, size and viscosity without taking the specific molecular structure into account. High β-glucan mutant barley, mother barley and oat β-glucans were large-scale extracted by comparable protocols using hot water, enzyme assisted hydrolysis and ethanol precipitation leading to similar molecular masses (200-300kDa). Multivariate data analysis on all compositional, structural and functional features demonstrated that the main variance among the samples was primarily explained by block structural differences as determined by HPSEC-PAD. In particular the barley high β-glucan mutant proved to exhibit a unique block structure with DP3 and DP4 contributions of: 78.9% and 16.7% as compared to the barley mother (72.1% and 21.4%) and oat (66.1% and 29.1%). This unique block structure was further confirmed by the (1)H NMR determination of the β-1,4 to β-1,3 linkage ratio. Low solubility of the barley samples was potentially an effect of substructures consisting of longer repetitive cellotriosyl sequences. FT-Raman and NMR spectroscopy were useful in measuring sample impurities of α-glucans and prediction of β-linkage characteristics.
authors.affiliation: Department of Food Science, University of Copenhagen, Frederiksberg C, Denmark. skau@life.ku.dk
authors.forename: Mette S
authors.initials: MS
authors.lastname: Mikkelsen
authors.forename: Birthe M
authors.initials: BM
authors.lastname: Jespersen
authors.forename: Flemming H
authors.initials: FH
authors.lastname: Larsen
authors.forename: Andreas
authors.initials: A
authors.lastname: Blennow
authors.forename: Søren B
authors.initials: SB
authors.lastname: Engelsen
mesh_terms: D018554:Avena / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005936:Glucans / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D001467:Hordeum / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D008970:Molecular Weight; D009154:Mutation
chemical_list: D005936:Glucans