PRODUCTION AND CHARACTERIZATION OF SHORT CHAIN LEVAN-TYPE FRUCTOOLIGOSACCHARIDES BY LEVANSUCRASE DERIVATIVE

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Short chain levan-type fructooligosaccharides (LFOSs) are nondigestible oligosaccharides and widely used in food industry. They are composed of beta-(2,6)-linked D-fructofuranosyl residues with beta-(2,1)-linkage at branch points. In this report, LFOSs with degree of polymerization between 3 to 5 residues were produced in high yield by levansucrase derivative N251Y (EC 2.4.1.10), using sucrose as a sole substrate. Production of LFOSs was carried out in 40% sucrose (w/v) in deionized water and 8.75 unit/gram of levansucrase derivative N251Y was employed over 24 h incubation time. The purification of LFOSs was performed by size-exclusion chromatography with Bio-Gel P-2 as a stationary phase. TLC and MALDI-TOF mass spectrometry analysis of the purified products indicated trifructooligosaccharide (504 g.mol-1), tetrafructooligosaccharide (666 g.mol-1) and pentafructooligosaccharide (825 g.mol-1) were produced with product distribution approximately 70%, 24%, 6% (mole fraction), respectively. Chemical structures of levan-type fructooligosaccharides were confirmed by 1H and 13C NMR analysis of both the purified fructooligosaccharides and their acetylated derivatives.