Evaluation of Prebiotic Glycan Composition in Human Milk and Infant Formula: Profile of Galacto-Oligosaccharides and Absolute Quantification of Major Milk Oligosaccharides by UPLC-Cyclic IM-MS and UPLC-MS/MS.

Prebiotic oligosaccharides have attracted immense interest in the infant formula (IF) industry due to their unique health benefits for infants. There is a need for the reasonable supplementation of prebiotics in premium IF products. Herein, we characterized the profile of galacto-oligosaccharides (GOS) in human milk (HM) and IF using ultrahigh-performance liquid chromatography-cyclic ion mobility-mass spectrometry (UPLC-cIM-MS) technique. Additionally, we further performed a targeted quantitative analysis of five essential HM oligosaccharides (HMOs) in HM (n = 196), IF (n = 50), and raw milk of IF (n = 10) by the high-sensitivity UPLC-MS/MS method. HM exhibited a more abundant and variable HMO composition (1183.19 to 2892.91 mg/L) than IF (32.91 to 56.31 mg/L), whereas IF contained extra GOS species and non-negligible endogenous 3'-sialyllactose. This also facilitated the discovery of secretor features within the Chinese population. Our study illustrated the real disparity in the prebiotic glycome between HM and IF and provided crucial reference for formula improvement.