The dried milk oligosaccharide extracts were reconstituted with DDI water to reach the final total carbohydrate concentration of 0.34 mg/mL, which is the same concentration as the 1 mM lactose solution. The reconstituted oligosaccharide samples were measured under the same protocol as above, with 600 spectra collected for each milk type. Before data analysis, the spectra were averaged for three batches, resulting in 200 spectra for each milk type.