Comprehensive identification and absolute quantification of milk oligosaccharides in 25 commercial young child formulas

This study comprehensively identified and quantified oligosaccharides (OSs) in 25 commercial young child formulas (YCFs) from China market. Using MALDI-TOF/TOF and UPLC-MS/MS, 196 OS structures were identified, of which 182 were common to all YCFs. The profile comprised 23 confirmed native bovine milk oligosaccharides (BMOs) while the majority (155 structures) likely originated from supplemented ingredients such as galacto-oligosaccharides (GOS) and fructo-oligosaccharides (FOS). Absolute quantification of eight OSs (2′-FL, 3-FL, LNnT, 3′-SL, 6′-SL, 3′-GL, 4′-GL, 6′-GL) revealed total abundances ranging from 1245.4 to 6728.1 μg g⁻¹. The GL isomers (3’/4’/6′-GL) were most abundant, consistent with GOS fortification, followed by the sialylated OSs (3′-SL and 6′-SL). In contrast, 2′-FL, 3-FL, and LNnT were present at relatively low levels. Clarifying OS origins along with their abundance is fundamental to a comprehensive understanding of YCFs, enabling accurate functional assessment and targeted product enhancement.