Structural characterisation of galacto-oligosaccharides (VITAGOS™) sythesized by transgalactosylation of lactose
Guo, Q., Goff, H.D., Cui, S.W. (2018). Structural characterisation of galacto-oligosaccharides (VITAGOS™) sythesized by transgalactosylation of lactose. Bioactive Carbohydrates and Dietary Fibre, [online] 14 33-38. http://dx.doi.org/10.1016/j.bcdf.2017.07.007
Plain language summary
This study provided detailed structural information on galacto-oligosaccharides, a type of sugar, produced from the whey of cheese making. Oligosaccharides produced by a Canadian company was fractionated into single oligosaccharides, then the detailed structures of each oligosaccharides was elucidated using 2D NMR spectroscopy. These results can be used to promote the use of galacto-oligosaccharides from cheese making as a food ingredient.
A galacto-oligosaccharide product (VITAGOS™) was prepared by glycoside hydrolases (β-galactosidase from Aspergillus oryzae and Kluyveromyces lactis) using lactose as substrate. Monosaccharide composition analysis indicated that VITAGOS™ contained 40.3% (w/w, dry basis) glucose and 51.1% (w/w, dry basis) galactose. According to high performance size exclusion chromatography (HPSEC) analysis, VITAGOS™ was a sugar mixture with degree of polymerisation (DP) ranging from 1 to 7, with DP2 and DP3 as the dominant fractions (32% and 33%, w/w). In addition, more than three fractions were observed for each DP pool indicated by the oligosaccharides profiles obtained from high performance anion exchange chromatography (HPAEC) analysis. Six sub-fractions (F1-F6, corresponding to DP1 to DP6 rich fraction, respectively) were then collected using biogel P-2 column, followed by structural characterisation through methylation analysis combined with 1D & 2D NMR spectroscopy. The detailed molecular structures of VITAGOS™ with DP up to 4 are provided.