Ventura Giovanni, Bianco Mariachiara, Losito Ilario, Cataldi Tommaso R I, Calvano Cosima D
Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, via Orabona 4, 70126 Bari, Italy.
Centro Interdipartimentale SMART, Università degli Studi di Bari Aldo Moro, via Orabona 4, 70126 Bari, Italy.
Int J Mol Sci. 2025 Jan 28;26(3):1120. doi: 10.3390/ijms26031120.
Kefir, a fermented milk product produced using kefir grains, is a symbiotic consortium of bacteria and yeasts responsible for driving the fermentation process. In this study, an in-depth analysis of kefir's lipid profile was conducted, with a focus on its phospholipid (PL) content, employing liquid chromatography with high-resolution mass spectrometry (LC-HRMS). Nearly 300 distinct polar lipids were identified through hydrophilic interaction liquid chromatography (HILIC) coupled with electrospray ionization (ESI) and Fourier-transform orbital-trap MS and linear ion-trap tandem MS/MS. The identified lipids included phosphatidylcholines (PCs), lyso-phosphatidylcholines (LPCs), phosphatidylethanolamines (PEs) and lyso-phosphatidylethanolamines (LPEs), phosphatidylserines (PSs), phosphatidylglycerols (PGs), and phosphatidylinositols (PIs). The presence of lysyl-phosphatidylglycerols (LyPGs) was identified as a key finding, marking a lipid class characteristic of bacterial membranes. This discovery highlights the role of viable bacteria in kefir and underscores its probiotic potential. The structural details of minor glycolipids (GLs) and glycosphingolipids (GSLs) were further elucidated, enriching the understanding of kefir's lipid complexity. Fatty acyl (FA) composition was characterized using reversed-phase LC coupled with tandem MS. A mild epoxidation reaction with meta-chloroperoxybenzoic acid (m-CPBA) was performed to pinpoint double-bond positions in FAs. The dominant fatty acids were identified as C18:3, C18:2, C18:1, C18:0 (stearic acid), C16:0 (palmitic acid), and significant levels of C14:0 (myristic acid). Additionally, two isomers of FA 18:1 were distinguished: ∆9-cis (oleic acid) and ∆11-trans (vaccenic acid). These isomers were identified using diagnostic ion pairs, retention times, and accurate / values. This study provides an unprecedented level of detail on the lipid profile of kefir, shedding light on its complex composition and potential nutritional benefits.
开菲尔是一种使用开菲尔粒生产的发酵乳制品，是负责驱动发酵过程的细菌和酵母的共生菌群。在本研究中，利用液相色谱-高分辨率质谱（LC-HRMS）对开菲尔的脂质谱进行了深入分析，重点关注其磷脂（PL）含量。通过亲水相互作用液相色谱（HILIC）结合电喷雾电离（ESI）、傅里叶变换轨道阱质谱和线性离子阱串联质谱/质谱，鉴定出近300种不同的极性脂质。鉴定出的脂质包括磷脂酰胆碱（PC）、溶血磷脂酰胆碱（LPC）、磷脂酰乙醇胺（PE）和溶血磷脂酰乙醇胺（LPE）、磷脂酰丝氨酸（PS）、磷脂酰甘油（PG）和磷脂酰肌醇（PI）。赖氨酰磷脂酰甘油（LyPG）的存在被确定为一项关键发现，它是细菌膜特有的一类脂质。这一发现突出了开菲尔中活菌的作用，并强调了其益生菌潜力。进一步阐明了次要糖脂（GL）和糖鞘脂（GSL）的结构细节，加深了对开菲尔脂质复杂性的理解。使用反相液相色谱结合串联质谱对脂肪酸（FA）组成进行了表征。用间氯过氧苯甲酸（m-CPBA）进行温和的环氧化反应，以确定脂肪酸中双键的位置。主要脂肪酸被鉴定为C18:3、C18:2、C18:1、C18:0（硬脂酸）、C16:0（棕榈酸），以及显著含量的C14:0（肉豆蔻酸）。此外，区分了脂肪酸18:1的两种异构体：∆9-顺式（油酸）和∆11-反式（反式vaccenic酸）。这些异构体通过诊断离子对、保留时间和精确的/值进行鉴定。本研究提供了关于开菲尔脂质谱前所未有的详细信息，揭示了其复杂的组成和潜在的营养益处。
