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This research aimed to investigate the characteristics of casein phosphopeptides in Chinese human milk, and their potential relationship to infant growth. Using the liquid chromatography-Orbitrap-mass spectrometry technique, a total of 15 casein phosphopeptides were identified from 200 human milk samples. Also, our results indicate that casein phosphopeptides were phosphorylated with only one phosphate. The relative concentrations of casein phosphopeptides at 6 months postpartum were increased compared with milk at 2 months (FDR < 0.05). Significantly positive correlations were observed between casein phosphopeptides and infant growth, as shown by four casein phosphopeptides were positively correlated with the infants' weight-for-age Z -scores (r s range from 0.20 to 0.29), and three casein phosphopeptides were positively correlated with the infants' length-for-age Z-scores (r s range from 0.19 to 0.27). This study is the first to reveal the phosphorylated level and composition of casein phosphopeptides in Chinese human milk, and their potential relationship with infant growth. [Display omitted] • First discovery of the composition of casein phosphopeptides in Chinese human milk. • Casein phosphopeptides in human milk were found to be hypo-phosphorylated. • Casein phosphopeptides increased with the duration of lactation. • Casein phosphopeptides were positively correlated to infant weight and length. [ABSTRACT FROM AUTHOR]

In this study, we aimed to detect the comprehensive fatty acid (FA) profile in human milk, including total fatty acids (total FAs), Sn-2 fatty acids (Sn-2 FAs), and phospholipid fatty acids (PLFAs), and further analyzed the influence of the sampling regions on human milk FA profile. The results showed that oleic acid (C18:1n9c), palmitic acid (C16:0), and linoleic acid (C18:2n6c) were the main FA species in total FAs, and Sn-2 C16:0 was the dominant Sn-2 FA species. Moreover, the PLFAs were mainly comprised of PL C16:0, PL stearic acid (PL C18:0), PL C18:1n9c, and PL C18:2n6c. Furthermore, FAs showed geographical differences, such as the highest content of linolenic acid (C18:3n3) and docosahexaenoic acid (C22:6n3) of total FAs was observed in Lanzhou and Weihai, respectively. Therefore, these results provide more FA data for the Chinese human milk database, and further enrich the theoretical information for the development of infant formula. [ABSTRACT FROM AUTHOR]

Human milk (HM) provides optimal nutrition for infants, but infant formula (IF) serves as a potential alternative to HM when breastfeeding is not an option. However, IF possesses a more intense aroma than HM, and it is often challenging to reduce this disparity due to its stringent production regulations. Therefore, investigating the interaction between HM proteins and odor molecules is essential for comprehending the distinct odor characteristics of HM and guiding improvements in IF to mimic the aroma of HM. This research aims to characterize the HM odor and explore the influence of HM α -lactalbumin (HMLB) on the release of HM odor skeleton compounds (OSC) using a combination of computer simulation, human perceptions, and instrumental analyses. A total of 20 OSCs were identified. Notably, the release of most of these compounds was negatively correlated with the HM protein content, with the strongest negative correlations being observed for hexanal, nonanal, and decanal (|R| ≥ 0.7, P < 0.01). The molecular docking simulations demonstrated that HMLB inhibited the volatilization of hexanal, nonanal, and decanal, thereby increasing the odor threshold of these odor compounds (61.94 %, 241.5 %, and 198.6 %). This inhibition was mainly achieved through the formation of hydrogen bonding and hydrophobic interactions, a finding corroborated by multi-spectroscopic analysis. Overall, the experimental results provide valuable insights into the odor mechanism of HM and contribute to the development of IF that mimics the HM odor. [Display omitted] • Twenty odor skeleton components (OSC) that make up HM odor were characterized. • Most of the OSCs were negatively correlated with the total protein content of HM. • Non-covalent interactions of OSCs with α -lactalbumin (HMLB) affected their release. • The quenching of OSCs fluorescence by HMLB was based on a static mechanism. • The odor thresholds of OSCs were significantly increased by HMLB. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ninety-four odor-active compounds were identified from HM by DHS-GC × GC-O-MS. • Nonanal and octanal were the most important odor-active compounds in most HM. • Fat content was closely related to the amounts of odor-active compounds in HM. • Aldehydes have most abundant species and the highest correlation with fat content. • HM odor attributes were contributed by synergistic effect of odor-active compounds. Odor is an important indicator of human milk (HM) quality, with a proven function. Here, the effect of inter-individual nutrient differences on key odor-active compounds (OACs) and odor attributes of HM samples was investigated using flavor analysis techniques and correlation network analysis. A total of ninety-four OACs were identified from 30 HMs, of which 24 key OACs could represent the basic odor characteristics of HMs. Fat content was closely related to the amounts of OACs, with aldehydes being the most abundant species and having the highest correlation with fat content. Of them, nonanal and octanal were the most important OACs in HM, having both high flavor dilution factor (2 ∼ 64, 4 ∼ 128) and odor activity values (<1 ∼ 37, 2 ∼ 36) in most samples. Additionally, different pattern of synergism between key OACs contribute to each odor attribute of HM. These findings will provide insights for subsequent in-depth studies of HM flavor. [ABSTRACT FROM AUTHOR]

• New SPE-UPLC-MS/MS method for simultaneous analysis of 20 oxylipins and 5 PUFAs. • Optimized solid-phase extraction and chromatographic conditions. • A rapid, sensitive and reproducible method for breast milk and infant formula. • Contents of oxylipins and PUFAs in breast milk were higher than infant formula. Oxylipins and their precursors (long-chain polyunsaturated fatty acids, LCPUFAs) are key intercellular signaling molecules influencing the inflammatory response. Each oxylipin has pro- and/or anti-inflammatory effects, and the relative abundance of different oxylipins can alter the inflammatory balance, making it important to clarify the oxylipin profile of breast milk for optimal infant health. The extraction, identification, and simultaneous quantification of oxylipins in breast milk are challenging due to the structural similarity, limited stability, and the low endogenous concentration of oxylipins and the complex matrix of breast milk. This study aimed to develop a solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry (SPE-UPLC-MS/MS) method for the comprehensive and specific quantification of oxylipins and their precursors in breast milk. The LC conditions (including column, mobile phase, and gradient conditions) and SPE procedure (including SPE cartridges, elution solvent, and elution volume) were optimized to achieve accurate quantification and better analyte recovery. A single 18-minute chromatographic run allows for the quantification of 20 oxylipins and 5 PUFAs. The results showed good linearity (R2 > 0.99) over the concentration range of 2 to 100 ng/mL, with the instrument detection limits ranging from 0.01 to 0.90 ng/mL for oxylipins and 0.02 to 0.59 ng/mL for PUFAs. The method is rapid, sensitive, and reproducible (RSD ≤ 10%) and is suitable for the quantitative analysis of oxylipins and their precursors in infant formula samples. [ABSTRACT FROM AUTHOR]