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This study provides insights into the composition and in-situ structures of the milk fat globule membrane (MFGM) in buffalo milk with different fat globule sizes (0.55 μm and 8.04 μm). Small fat globules contained a higher amount of MFGM proteins and polar lipids, while the content of MFGM components (except for ADPH) was greater per unit membrane area in large fat globules. A total of 386 differentially expressed proteins were identified, with many of the most differentially expressed proteins being associated with human diseases, such as cancer and elderly diseases. The coverage of sphingomyelin and certain MFGM proteins (BTN and PAS 6/7) on large fat globules was higher, potentially linked to the presence of larger, irregular lipid rafts and patch-shaped glycocalyxes, respectively. These findings suggest that small fat globules are suitable for nutritional fortification of buffalo milk, while large fat globules are appropriate for the preparation of functional dairy-based ingredients. • The membranes of buffalo milk fat globules with different sizes were fully studied. • Major MFGM proteins and PLs were enriched in the small-sized fat globule fractions. • Most differentially expressed proteins were involved in Human Diseases. • Large and irregular lipid rafts existed in large fat globules. • Small circular lipid rafts and fewer glycocalyxes existed in small fat globules. [ABSTRACT FROM AUTHOR]

Milk fat globule membrane (MFGM) proteins are receiving increased attention due to their reported benefits for human health, particularly in infant populations. Challenges exist in MFGM protein quantification due to their low quantities, complex chemistry, interactions with other matrix components, and the high matrix complexity. In this study, a subset of four MFGM proteins were selected as relevant targets for identification and quantification in an infant formula (IF) matrix: butyrophilin, mucin 1, xanthine dehydrogenase/oxidase, and perilipin 2. An analytical protocol for absolute quantification of these four MFGM proteins in IF was successfully developed and validated. Additionally, the feasibility to apply the method in selected MFGM ingredients was also demonstrated. The method demonstrated good performance; high accuracy and robustness, low LOQ and uncertainty, while controlling the matrix effect. This study represents a report of an analytical method to quantify selected MFGM proteins in IF. • The matrix effect from infant formula had a major impact on protein quantification. • The method was also applied for use in milk fat globule membrane ingredients. • Of the four proteins studied, Butyrophilin had the highest concentration. • Of the four proteins studied, Mucin 1 had the lowest concentration. • The method showed high sensitivity and precision, and low uncertainty. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect mechanism of MFGM proteins on the acid-tolerant survival of Lactobacillus was first revealed. • MFGM proteins could improve the survival ability of bacteria under low acid conditions. • Protein differences were analyzed by Tandem Mass Tags (TMT) proteomics. The prerequisite for lactic acid bacteria to perform their probiotic function is that they could survive the acid-stressed environment of production and application. In this experiment, the protective mechanism of milk fat globule membrane (MFGM) proteins on lactic acid bacteria under acid stress was investigated. Scanning electron microscopy and fluorescence probe were used to analyze the condition of the acid-treated bacteria, which showed that MFGM proteins could enhance the survival ability of Lactobacillus acidophilus CICC 6074 under acid stress by maintaining cell morphology, elevating intracellular pH and H+-ATPase activity. Furthermore, Tandem Mass Tags (TMT) proteomic analysis revealed that MFGM protein could exert protective effects on L. acidophilus CICC 6074 by regulating amino acid metabolism, ATPase activity, peptidoglycan synthesis, gene repair and heritage, etc. The results will provide a new approach for the protection and development of functional lactic acid bacteria. [ABSTRACT FROM AUTHOR]

[Display omitted] • The cream separated from the milk rich in LFGs contains more MFGM proteins. • The new emulsion preparation method omits a pre-emulsification step. • The emulsions prepared by the new method showed higher stability. • The interfacial protein number was approximately 2-fold higher on NE-2 than CE-2. • All major MFGM proteins were identified at the interface of NE-2 rather than CE-2. Milk fat globule membrane (MFGM) proteins have several biological functions and maintain the fat globule structure. However, the major MFGM protein compositions in simulated human milk emulsions are different from those in human milk due to the composition loss in the isolation process of MFGM materials. To overcome this limitation, we developed a novel strategy, namely, the solution enriched with MFGM was homogenized with cream separated from the milk rich in large-sized fat globules. The results of physicochemical properties and the interfacial protein coverage of the emulsions showed that the emulsions prepared by the new method had a smaller particle size, higher stability, and more interfacial protein coverage when the ratio of fat to protein was 1:3. In addition, proteome differences in interfacial proteins between the new emulsions and simulated infant formula emulsions were investigated, and the results revealed that the interface of the emulsions prepared by the new method contained all major MFGM proteins and unique GO annotations and KEGG pathways. However, only four MFGM proteins (XO, ADPH, PAS 6/7) were quantified at the interface of the emulsions prepared by the common method. Furthermore, the protein number and the total relative abundance of major MFGM proteins were approximately 2-fold and 475-fold higher at the interface of the emulsions prepared by the new method compared to the common method. Overall, the study modulated the interfacial protein composition of fat globules by screening the sources of lipid and homogenization methods and revealed its potential effect on processing stability and biological properties. [ABSTRACT FROM AUTHOR]

Abstract: The membrane surrounding fat globules in milk, called the milk fat globule membrane (MFGM), represents a unique biophysical system. Over the last two decades, a great deal of knowledge on the intracellular origin, composition and structure of MFGM has been accumulated. In recent years, several health-beneficial components of MFGM have been identified, which consequently has led to increasing interest in developing MFGM as a food ingredient with unique functional properties and health benefits. This review focuses on current research relating to the composition and structure of MFGM, and interactions of MFGM with skim milk proteins during heat treatments. Various methods of isolating MFGM, reported in the literature, are reviewed and evaluated for their potential to produce MFGM ingredients for food applications. The functional properties of MFGM components, particularly their ability to stabilize oil-in-water emulsions and to form liposomes for the delivery of bioactive compounds, are discussed. Areas for future research are identified. [Copyright &y& Elsevier]