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Determinationof trans-Galacto-oligosaccharides
(TGOS) in InfantMilk Formula
Ion-ExchangeChromatography
(Applicable to the quantitative determination of added trans-galacto-oligosaccharides
in Infant Milk Formula.)
Updated version: submitted on23th of July 2014
Principle:
Galacto-oligosaccharides also known as oligogalactosyllactose, oligogalactose, or
transgalacto-oligosaccharides (TOS) produced by transgalactosylation of lactose.
This
assay has been set up to determine the GOS content in Infant Milk Product.
The disadvantage of the currently used AOAC 2001method is that themeans of
removing the lactose from IMF is not robust. If the lactose is not removed from IMF,
then the concentration is too high compared to the GOS concentration. Both
contribute to the galactose content after enzymation, so the contribution fromGOS
cannot bemeasured correctly. By removing the free lactose from the GOS in IMF
with a chromatographic preparative step before hydrolyzation reliable results can be
obtained.
Fractionation is performed on HPAEC equipment. The collected fraction is treated
with SPE to remove all salts from themobile phase used in the chromatographic
preparative step. After SPE the fluids are removed by a speedvac. The GOS is
obtained in a solid form in a 2mL safelock tube.
The buffer (used for the enzymatic treatment) including a suitable sugar as internal
standard (e.g. ribose) is added to dissolve GOS. Part of the solution is used for the
enzymatic treatment; the other part is used to determine the residual lactose
concentration in the fraction (no enzyme added).
After enzymatic treatment both solutions are analyzed on HPAEC-PAD to determine
the galactose, ribose and lactose concentrations. The GOS concentration is described
as%galactose fromGOS. The galactose concentration needs to be corrected for the
residual lactose in the fraction.
GOS-02
FORWORKINGGROUP/ERPUSEONLY
DONOTDISTRIBUTE
