Browsing by Author "Hou, Yaxi"

Non-digestible oligosaccharides possess important physicochemical and physiological properties. They have gained great attention because of their potential prebiotic properties. The oligosaccharides have wide food industrial applications as dietary fibers, sweeteners, humectants, and possible weight controlling agents. In this thesis, cloned Weissella confusa VTT E-90392 dextransucrase was used to catalyze the synthesis of oligosaccharides (acceptor products) by acceptor reaction, when sucrose was the glucosyl unit donor. Maltose acceptor reaction was selected to analyze the effects of the concentrations of sucrose and maltose, as well as the dosages of dextransucrase on maltose acceptor products. Other acceptor reactions were also evaluated, with primary lactose and cellobiose acceptor products being purified and partially characterized by MS/MS. Concentrations of sucrose and maltose, as well as their interactions were the most important factors regarding isomalto-oligosaccharides production. The production of overall oligosaccharides could be increased by increasing sucrose and maltose concentrations. Lactose, cellobiose, other disaccharides and trisaccharides could be acceptors for W. consufa dextransucrase. In combination with the structures from previous publications, 2-a-Dglucopyranosyl-cellobiose and 2-a-D-glucopyranosyl-lactose were probably the primary products for cellobiose and lactose, although one trisaccharide synthesized by lactose acceptor reaction remains unknown. In order to verify the characterization, NMR spectroscopic analysis is needed for further study. In conclusion, W. consufa dextransucrase is capable of catalyzing oligosaccharides synthesis, and acceptor reactions would be promising methods in producing prebiotic oligosaccharides.