STRUCTURAL DETERMINATION OF SOME NEW OLIGOSACCHARIDES AND ANALYSIS OFTHE BRANCHING PATTERN OF ISOMALTOOLIGOSACCHARIDES FROM BEER

Separation of the low molecular weight fraction of oligosaccharides fr om beer and subsequent NMR analysis led to the identification of sever al new derivatives of trehalose, sucrose, maltooligosaccharides glucos ylated at O-2 of reducing end Glc, and linear Glc oligomers with alpha -(1-->3) and alpha-(1-->4)-linkages. Reducing oligosaccharides were la beled with 7-amino-4-methylcoumarin by reductive amination, separated according to their molecular weight and the branching pattern was stud ied using enzymatic (pullulanase) degradation in combination with MALD I-TOF mass spectrometry and HPLC analysis. It was found that up to DP 10 isomaltooligosaccharides mostly consisted of a linear reducing alph a-(1-->4)-linked Glc chain substituted by single maltose or maltotrios e residue at O-6 of any residue except the reducing one. (C) 1998 Else vier Science Ltd. All rights reserved.