title: Structure of Brewer's Spent Grain Lignin and Its Interactions with Gut Microbiota in Vitro.
abstract: Lignin is part of dietary fiber, but its conversion in the gastrointestinal tract is not well understood. The aim of this work was to obtain structural information on brewer's spent grain (BSG) lignin and to understand the behavior of the polymeric part of lignin exposed to fecal microbiota. The original BSG and different lignin fractions were characterized by pyrolysis-GC/MS with and without methylation. Methylation pyrolysis proved that the ratio between guaiacyl and syringyl units was similar in all lignin samples, but the ratio between p-coumaric and ferulic acids varied by the isolation method. Combined pyrolysis results indicated higher acylation of γ-OH groups in syringyl than in guaiacyl lignin units. The polymeric lignin structure in the alkali-soluble fraction after enzymatic hydrolysis was slightly altered in the in vitro colon fermentation, whereas lignin in the insoluble residue after enzymatic treatments remained intact.
authors.affiliation: VTT Technical Research Centre of Finland Ltd. , P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
authors.forename: Taina
authors.initials: T
authors.lastname: Ohra-aho
authors.affiliation: VTT Technical Research Centre of Finland Ltd. , P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
authors.forename: Piritta
authors.initials: P
authors.lastname: Niemi
authors.affiliation: VTT Technical Research Centre of Finland Ltd. , P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
authors.forename: Anna-Marja
authors.initials: AM
authors.lastname: Aura
authors.affiliation: Department of Environmental and Earth Sciences, University of Milano-Bicocca , Piazza della Scienza 1, Milan, I-20126 Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Orlandi
authors.affiliation: VTT Technical Research Centre of Finland Ltd. , P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
authors.forename: Kaisa
authors.initials: K
authors.lastname: Poutanen
authors.affiliation: Natural Resources Institute Finland , Viikinkaari 4, FI-00790 Helsinki, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Buchert
authors.affiliation: VTT Technical Research Centre of Finland Ltd. , P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Tamminen
mesh_terms: D003106:Colon / Q000378:metabolism / Q000382:microbiology; D002523:Edible Grain / Q000737:chemistry / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D000069196:Gastrointestinal Microbiome; D006801:Humans; D008031:Lignin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008031:Lignin
keywords: Py-GC/MS; TMAH/Py; brewer’s spent grain; colon microbiota; in vitro fermentation; lignin