Determination of β-Galactooligosaccharides (GOS) in Infant Formula and Adult Nutritionals: Single-Laboratory Validation, First Action 2021.01

Background beta-Galactooligosaccharides (GOS) are typically used in infant formula and adult nutritionals as a source of nondigestible oligosaccharides, which may bring beneficial effects through modulation of the gut microbiota. However, suitable methods for the determination of GOS in products with a high background of lactose do not exist. Objective The aim of this work was to develop a method suitable for the determination of GOS in infant formula and adult nutritionals and demonstrate suitability through single laboratory validation. Methods Reducing oligosaccharides are labeled with 2-aminobenzamide (2AB), separated by hydrophilic interaction LC, and determined assuming that all oligosaccharides give an equimolar response in the detector. The same sample is analyzed a second time after treatment with beta-galactosidase to remove GOS. The difference in the determined oligosaccharides between the two measurements will be the GOS content of the sample. The method was validated in a single laboratory on infant formula and adult nutritionals. Results Recoveries were in the range 91.5-102%, relative standards of deviation (RSDr) were in the range 0.7-5.99%, and one sample had an RSDr of 8.30%. Except for the one sample with an RSDr of 8.30%, the performance is within the requirements outlined in the Standard Method Performance Requirements, which specifies recoveries in the range 90-110% and RSDr of below 6%. Conclusions The method is suitable for the determination of GOS in infant formula and adult nutritionals.