title: Modifications of Saccharomyces pastorianus cell wall polysaccharides with brewing process.
abstract: The cell wall polysaccharides of brewers spent yeast Saccharomyces pastorianus (BSY) and the inoculum yeast (IY) were studied in order to understand the changes induced by the brewing process. The hot water and alkali extractions performed solubilized mainly mannoproteins, more branched for BSY than those of IY. Also, (31)P solid state NMR showed that the BSY mannoproteins were 3 times more phosphorylated. By electron microscopy it was observed that the final residues of alkali sequential extraction until 4M KOH preserved the yeast three-dimensional structure. The final residues, composed mainly by glucans (92%), showed that the BSY, when compared with IY, contained higher amount of (1→4)-linked Glc (43% for BSY and 16% for IY) and lower (1→3)-linked Glc (17% for BSY and 42% for IY). The enzymatic treatment of final residue showed that both BSY and IY had (α1→4)-linked Glc and (β1→4)-linked Glc, in a 2:1 ratio, showing that S. pastorianus increases their cellulose-like linkages with the brewing process.
authors.affiliation: QOPNA Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Rita
authors.initials: R
authors.lastname: Bastos
authors.affiliation: QOPNA Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal. Electronic address: ecoelho@ua.pt.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Coelho
authors.affiliation: QOPNA Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Coimbra
mesh_terms: D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism; D002480:Cellulase / Q000378:metabolism; D006868:Hydrolysis; D006878:Hydroxides / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D017680:Potassium Compounds / Q000737:chemistry; D012440:Saccharomyces / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D006878:Hydroxides; D011134:Polysaccharides; D017680:Potassium Compounds; D014867:Water; D000516:alpha-Amylases; D002480:Cellulase; C029943:potassium hydroxide
keywords: Alcoholic fermentation stress; Brewers spent yeast; Glucan; Mannoprotein; Sequential extraction