title: Characterization of an unexpected bioemulsifier from spent yeast obtained from Thai traditional liquor distillation.
abstract: Crude biopolymer was extracted from spent yeast, lyophilized and fractionated on Sephadex G-100 to yield two fractions coded as fraction I and II. Fraction I was composed of both carbohydrates and proteins, showing emulsifying activity whereas fraction II consisted of only proteins and possessed no activity. Hence composition and chemical characterization of the purified fraction I (bioemulsifier) was analyzed using various analytical techniques. It was found that the sample contained 96% of carbohydrates consisting mainly of glucose with minor quantities of mannose, and 4% of protein built from 17 amino acids with the highest content of serine followed by alanine. The results also indicated that the sample was protein-bound glucan with the average molecular weight of 1.93×10(5) Da. The functional groups and primary structure of the sample were revealed by FT-IR and NMR techniques. The data demonstrate that the sample comprises a mixture of (1→4)-α- and (1→3)-β-D-glucans bound with protein. Enzymatic hydrolyses using α-amylase and endo 1,3-β-D-glucanase confirmed the presence of both glucans. Therefore, this bioemulsifier was identified as glucan-protein complex which is different from usual mannoprotein emulsifier derived from yeasts.
authors.affiliation: Department of Industrial Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
authors.forename: Paweena
authors.initials: P
authors.lastname: Dikit
authors.forename: Pawadee
authors.initials: P
authors.lastname: Methacanon
authors.forename: Wonnop
authors.initials: W
authors.lastname: Visessanguan
authors.forename: Aran
authors.initials: A
authors.lastname: H-kittikun
authors.forename: Suppasil
authors.initials: S
authors.lastname: Maneerat
mesh_terms: D000434:Alcoholic Beverages / Q000032:analysis*; D000596:Amino Acids / Q000032:analysis; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D057168:Distillation / Q000379:methods*; D045703:Emulsifying Agents / Q000737:chemistry* / Q000302:isolation & purification; D043326:Glucan 1,3-beta-Glucosidase / Q000378:metabolism; D006868:Hydrolysis; D007220:Industrial Waste / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013785:Thailand; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D000596:Amino Acids; D045703:Emulsifying Agents; D007220:Industrial Waste; D000516:alpha-Amylases; D043326:Glucan 1,3-beta-Glucosidase