title: Identification of alpha-D-glucosylglycerol in sake.
abstract: alpha-D-Glucosylglycerol (GG) was found for the first time in sake (Japanese rice wine) in an amount of about 0.5%. GG was also found in miso and mirin which had been brewed by using koji. GG was hydrolyzed into glucose and glycerol in an equimolar ratio with maltase (EC 3.2.1.20, alpha-glucosidase from yeast), but not with emulsin (EC 3.2.1.21, beta-glucosidase from almond). The retention times and mass spectra of trimethylsilyl derivatives by a GC-MS analysis of GG in sake were comparable to those of various GG samples synthesized by glycol cleavage. It was proven that GG in sake consisted of three components, viz., 2-O-alpha-D-glucosyl-glycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). The ratio of the three components in GG was 6:66:28 for sake. It is considered that GG was formed by transglucosylation of the glucosyl groups to glycerol by alpha-glucosidase from koji in the sake mash.
authors.affiliation: Tatsuuma-honke Brewing Co., Ltd., Nishinomiya City, Hyogo, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Takenaka
authors.forename: H
authors.initials: H
authors.lastname: Uchiyama
authors.forename: T
authors.initials: T
authors.lastname: Imamura
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002854:Chromatography, Paper; D008401:Gas Chromatography-Mass Spectrometry; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification*; D015394:Molecular Structure; D012275:Oryza; D014920:Wine / Q000032:analysis*
chemical_list: D005960:Glucosides; C034727:glucosylglycerol