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Single Lab Validation Report for GOS in Infant Formula and Adult Nutritionals
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Introduction
Currently, the standard method for analyzing GOS in food products is AOAC 2001.02 (De Slegte, 2002).
GOS (and lactose) in the sample are hydrolyzed with an enzyme to galactose and glucose. GOS content is
calculated from the difference in galactose content of a hydrolyzed and non-hydrolyzed sample. An
important advantage is that other non-digestible oligosaccharides do not interfere with the method.
The disadvantage of the AOAC 2001.02 method for IFT is that the high lactose content in IFT results in a
high quantity of galactose formed after hydrolysis. The resulting galactose quantity released from
lactose is very high compared to the galactose quantity released from GOS. For the GOS calculation this
means two large numbers are subtracted, which leads to an estimate for GOS content that is not precise
(reproducibility typically 10 – 15%). Precipitation with cold ethanol can be applied to remove part of the
lactose. However, a considerable amount of lactose remains and part of GOS may be removed as well.
In the currently proposed method, which is developed in collaboration with Danone Nutricia Research,
lactose is removed before hydrolysis in a chromatographic preparative step and this leads to more
precise results. The method consists of the following steps: 1) preparative separation, 2) SPE purification
and concentration, 3) enzymatic hydrolysis, and 4) HPAEC-PAD analysis.
GOS-02 SLV
FOR ERP USE ONLY
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