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Comparative studies employing different organic solvents on
the removal of dextrins from the coupling sugar mixture
revealed that the precipitation of dextrin was not
pronounced when propanol, acetone or n-butanol were used.
Addition of methanol with 4.5 times the volume of coupling
sugar mixture effectly removed 54％ dextrins. However,
only 3 times the volume of reaction mixture was required
to obtain the same quantity of dextrins precipitation when
ethanol was in use. Therefore, the coupling sugar content
rised from 17.6％ to 30.8％, with 75％ increase. Coupling
sugar mixture which had been treated with ethanol to
partially remove dextrins was successfully applied on 2-meter
Bio-Gel P-2 column at 55℃ and 60ml/h to separate each sugar.
One ml of 85％ ethanol-soluble coupling sugar solution was
optimal for the separation process. The resolution values of
sucrose and coupling sugar were 1.310 and 1.079 respectively,
with excellent separation performance. An aliquot of 1ml of
60％ coupling sugar mixture without removal of dextrins was
satisfactorily applied to the same column for separating each
component. The resolution values of peaks were larger than 1.
But the total coupling sugar was only up to 14.4％.
Eliminating CGTase inhibition simplified the process of
coupling sugar production. The separation performance on Bio-
Gel P-2 column at 55℃ and 60ml/h was excellent in
separating each component from ethanol-soluble portion of
coupling sugar mixture. Results from HPLC analysis on
fractions collected showed that the recoveries of maltosyl
fructoside and maltotriosyl fructoside were 87.3％ and 72.6％
respectively, and the individual purities were 96.3％ and
98.9％.
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