Lipid Profile Determination by Direct Infusion ESI-MS and Fatty Acid Composition by GC-FID in Human Milk Pools by Folch and Creamatocrit Methods

Human milk (HM) is extremely important to the baby, containing a varied and balanced range of nutrients fundamental to the ideal development of the newborn. Among these nutrients, HM lipids provide 40-60% of the energy. In HM banks, the creamatocrit method is employed as a quick and solvent-free tool, however, since Folch methodology is considered reference for lipid extraction, this study compared the fatty acid (FA) composition and the lipid profile by gas chromatography with flame ionization detector (GC-FID) and direct infusion by electrospray ionization mass spectrometry (DI-ESI-MS) in pools of different HM phases, obtained from Folch and creamatocrit methods, in order to elucidate which method provides better information about HM lipids. Lipid compositon results by Folch were superior to the results obtained by creamatocrit in HM pools investigated. It means, the lipid profiles of all HM pools were more intense, and the number of FA identified by Folch was also higher in comparison to the creamatocrit method (21 and 6 FAs, respectively). GC-FID analysis in combination with principal component analysis (PCA) divided the methods, confirming a greater contribution of the Folch method. Therefore, Folch methodology revealed an effective lipid extraction in comparison to creamatocrit method.

人乳（Human milk, HM）对婴儿极为重要，其含有多样且均衡的营养素，这些营养素是新生儿理想发育的基础。其中，人乳脂质可提供40%~60%的能量。在人乳库中，乳脂比容法（crematocrit method）常被用作快速且无需溶剂的检测手段，但由于Folch法（Folch methodology）被视为脂质提取的参考标准，本研究采用气相色谱-火焰离子化检测器（gas chromatography with flame ionization detector, GC-FID）与电喷雾电离质谱直接进样法（direct infusion by electrospray ionization mass spectrometry, DI-ESI-MS），对比了通过Folch法和乳脂比容法获得的不同相别人乳混合样品的脂肪酸（fatty acid, FA）组成与脂质谱，以阐明哪种方法能更精准地反映人乳脂质信息。在所检测的人乳混合样品中，Folch法得到的脂质组成结果优于乳脂比容法。具体而言，所有人乳混合样品的脂质谱信号更强，且Folch法鉴定出的脂肪酸数量也多于乳脂比容法（分别为21种和6种）。结合主成分分析（principal component analysis, PCA）的气相色谱-火焰离子化检测器分析结果可区分两种检测方法，证实了Folch法具有更优异的表现。因此，相较于乳脂比容法，Folch法能实现更高效的脂质提取。