title: Valuation of brewers spent yeast polysaccharides: a structural characterization approach.
abstract: Brewers spent yeast (BSY) is a by-product from beer industry that can be exploited as source of glucans and mannoproteins, with potential biological activities. In order to solubilize these carbohydrate-rich polymeric materials, a sequential extraction with hot water and alkaline solutions (0.1-8 M KOH) was performed. Mannoproteins were mainly (85%) extracted with 4 M KOH whereas glucans were extracted with 8 M KOH and in an amount that accounted only for 34% of total glucose. Final residue still accounted for 34% of the initial glucans and contained 98% of glucose. Cellulase and α-amylase treatments showed the presence of both α- and β-(1→4)-Glc linkages. To promote total solubilization of these insoluble glucans, the final residue was submitted to a partial acid hydrolysis. This work is the first report showing that the most abundant polysaccharides in BSY are polymers that contain structural features similar to cellulose, thus justifying their resistance to alkaline extractions, acid hydrolysis, and insolubility in water.
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Mariana
authors.initials: M
authors.lastname: Pinto
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: Centro de Biologia Celular, Departamento de Biologia, Secção Autónoma de Ciências da Saúde, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Nunes
authors.affiliation: Unicer Bebidas, SA, Leça do Balio, 4466-955 S. Mamede de Infesta, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Brandão
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: D001515:Beer; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D019649:Food Industry; D006026:Glycoside Hydrolases / Q000737:chemistry; D006868:Hydrolysis; D006878:Hydroxides / Q000737:chemistry; D007220:Industrial Waste; D011134:Polysaccharides / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D007220:Industrial Waste; D011134:Polysaccharides; D017680:Potassium Compounds; D006026:Glycoside Hydrolases; C029943:potassium hydroxide
keywords: Cellulose; Glucans; Mannoproteins; Partial acid hydrolysis; Saccharomyces; Sequential extraction