Quantitation of bioactive components in infant formulas: Milk oligosaccharides, sialic acids and corticosteroids

Structural Characterization and Abundance of Sialylated Milk Oligosaccharides in Holstein Cows during Early Lactation

Among other bioactive molecules, milk contains high amounts of sialylated milk oligosaccharides (MOs) that influence numerous processes in the offspring. For instance, sialylated MOs inhibit the invasion of pathogens and positively influence the gut microbiome to support the optimal development of the offspring. For these reasons, sialylated MOs are also used in infant formula as well as food supplements and are potential therapeutic substances for humans and animals. Because of the high interest in sialylated bovine MOs (bMOs), we used several analytical approaches, such as gas and liquid chromatography in combination with mass spectrometry, to investigate in detail the profile of sialylated bMOs in the milk of Holstein Friesian cows during early lactation. Most of the 40 MOs identified in this study were sialylated, and a rapid decrease in all detected sialylated bMOs took place during the first day of lactation. Remarkably, we observed a high variance within the sialylation level during the first two days after calving. Therefore, our results suggest that the content of sialylated MOs might be an additional quality marker for the bioactivity of colostrum and transitional milk to ensure its optimized application for the production of milk replacer and food supplements.

Rapid method for quantitation of seven human milk oligosaccharides in infant formula and premix

As the evidence supporting the beneficial effects of human milk oligosaccharides (HMOs) grows, so does the commercial interest in their inclusion in infant formula products. This also requires analytical methods capable of their quantification from finished infant formula products as well as from premixed ingredients in some cases. The objective of the present study was the development and single-laboratory validation of a method that can be used for this purpose for seven HMOs: 2'-fucosyllactose (2'FL), 3-fucosyllactose (3FL), difucosyllactose (DFL), 3'-sialyllactose (3'SL), 6'-sialyllactose (6'SL), lacto-N-tetraose (LNT), and lacto-N-neotetraose (LNnT). The present method uses labeling by reductive amination, with 4-aminobenzoic acid ethyl ester (benzocaine) as the labeling reagent and picoline borane as the reducing agent, then applies HPLC separation with UV detection. The seven HMOs could be analyzed from infant formula and premix samples with recoveries between 91 and 108 %, relative standard deviations of 4.3 % or lower across all replicates, and limits of quantitation between 0.001 % and 0.004 % of powder sample by weight. The method was found to be rapid and reliable, with a runtime of only 14 min per injection, in contrast to other methods found in literature which typically use nearly or more than an hour. In addition, it uses instrumentation that's readily available in most analytical laboratories.

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.

Characterization of milk oligosaccharide and sialic acid content and their influence on brain sialic acid in a lean mouse model for gestational diabetes

Oligosaccharides and sialic acids (Sia) are bioactive components in milk that contribute to newborn development and health. Hyperglycemia in pregnancy (HIP) can have adverse effects on both mother and infant. HIP is associated with low-grade systemic inflammation. Inflammation influenced glycan composition, particularly of Sia-containing structures. We hypothesize that HIP and high-fat diet influence milk oligosaccharide composition, particularly sialylated oligosaccharides. Furthermore, we propose that milk Sia content influences pup brain Sia content. To test these hypotheses we (i) characterize mouse milk oligosaccharides and Sia concentrations in mouse milk of a GDM mouse model with dietary fat intake intervention; and (ii) determine Sia levels in offspring brains. The concentrations of oligosaccharides and Sia in mouse milk and offspring's brains were quantified using UPLC-FLD analysis. Analyses were performed on surplus samples from a previous study, where HIP was induced by combining high-fat diet (HF) feeding and low-dose streptozotocin injections in C57Bl/6NTac female mice. The previous study described the metabolic effects of HIP on dams and offspring. We detected 21 mouse milk oligosaccharides, including 9 neutral and 12 acidic structures using UPLC-MS. A total of 8 structures could be quantified using UPLC-FLD. Maternal HIP and HF diet during lactation influenced sialylated oligosaccharide concentrations in mouse milk and total and free sialic acid concentrations. Sia content in offspring brain was associated with total and free Neu5Gc in mouse milk of dams, but no correlations with HIP or maternal diet were observed.