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Recent studies have demonstrated the positive effects of regular intake of milk fat globule membranes (MFGMs) on neural and cognitive development, as well as immune and gastrointestinal health in infants and elders. Dairy products and by-products generated from the butter and butter oil manufacturing process are valuable sources of MFGM. Thus, in view of the growing need to reduce by-products and waste, it is crucial to foster research aimed at the valorization of dairy by-products rich in MFGM. For this purpose, all the by-products coming from butter and butter oil production (from raw milk to the related by-products) were used to study the MFGM isolated fractions, followed by their characterization through a combined lipidomic and proteomic approach. The patterns of polar lipids and proteins indicated that buttermilk (BM), butterserum (BS), and their mix (BM-BS blend) are the most suitable by-products to be employed as starting material for the isolation and purification of MFGMs, thus obtaining MFGM-enriched ingredients for the manufacture of products with high biological activity. [ABSTRACT FROM AUTHOR]

Human and animal milk contain a rich variety of milk proteins that meet the needs of their newborns. In total, 1263 skim milk proteins and 1754 MFGM proteins were identified in human milk and six types of animal milk, respectively. Both similarities and differences were observed among the species. Human milk contained more immunoglobulins involved in the adaptive immune response, playing a crucial role in mucosal defense in newborn babies. In contrast, ruminant milk contained higher amounts of antimicrobial proteins, which protect newborns from bacterial infections. The most dominant difference in MFGM proteins between human and animal milk was related to protein processing in the endoplasmic reticulum. Goat milk and camel milk were more similar to human milk in terms of skim milk and MFGM proteins compared to the other five types of animal milk. Moreover, immunoglobulins and complement and coagulation cascade proteins in goat milk were most similar to those in human milk. A higher content of immunoglobulin A was observed in donkey milk, which could be considered as a source of IgA in infant formula. These results provide more comprehensive and novel insights into protein variation among animal milk, which may support improving dairy products such as infant formula.

Dietary proteins play important roles in the growth and reproduction of sheep, and the ewe's demand for proteins increases dramatically during late pregnancy. This research aimed to investigate the effect of dietary crude protein (CP) levels during late pregnancy on colostrum fat globule membrane (MFGM) protein and the growth performance of Hu sheep and their offspring, and provide a reference for the protein intake of ewes during late pregnancy. A total of 108 multiparous Hu sheep (45.6 ± 1.18 kg) were selected for this study, then 60 pregnant ewes confirmed by B-scan ultrasonography were randomly divided into three treatments (20 ewes/treatment) and fed by total mixed ration pellet with CP levels at 9.00% (LP), 12.0% (MP), and 15.0% (HP) during late pregnancy, respectively. The weight and dry matter intake of ewes during late pregnancy were recorded to calculate the average daily gain (ADG) and feed conversion ratio (FCR). Twin lambs were weighed on days 0, 7, 14, 30, 60, and 180 after birth to calculate ADG. Meanwhile, the colostrum of ewes was collected within 12 h after delivery. The colostrum MFGM proteins were identified and quantified by the isobaric tag for relative and absolute quantification (iTRAQ) coupled with liquid chromatography-tandem mass spectrometry methods. In addition, biological functions of differentially expressed proteins (DEPs) were annotated by Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The results revealed that a 15.0% CP level had significant effects on the BW of lambs on days 0, 7, and 30 (P < 0.05). Notably, a total of 1,529 MFGM proteins were identified and 286 DEPs were found among three treatments. Functional analysis showed that DEPs were mainly involved in cell growth, differentiation, and tissue repair, and involved in metabolic pathways, such as the porphyrin and chlorophyll metabolism pathways. In this study, lambs in HP treatment had better growth performance; moreover, dietary 15.0% CP level also affected the colostrum MFGM proteins composition of Hu ewes. These observations can facilitate future studies on the feeding regimen of ewes during late pregnancy.

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]

Recent studies have demonstrated the positive effects of regular intake of milk fat globule membranes (MFGMs) on neural and cognitive development, as well as immune and gastrointestinal health in infants and elders. Dairy products and by-products generated from the butter and butter oil manufacturing process are valuable sources of MFGM. Thus, in view of the growing need to reduce by-products and waste, it is crucial to foster research aimed at the valorization of dairy by-products rich in MFGM. For this purpose, all the by-products coming from butter and butter oil production (from raw milk to the related by-products) were used to study the MFGM isolated fractions, followed by their characterization through a combined lipidomic and proteomic approach. The patterns of polar lipids and proteins indicated that buttermilk (BM), butterserum (BS), and their mix (BM-BS blend) are the most suitable by-products to be employed as starting material for the isolation and purification of MFGMs, thus obtaining MFGM-enriched ingredients for the manufacture of products with high biological activity.

[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]

In comparison to skim milk and whey, buttermilk and butter serum contain high amounts of functional milk fat globule membrane (MFGM) proteins. Quantification of MFGM proteins is difficult because no analytical standard material is available. By means of conventional SDS-PAGE with subsequent staining, MFGM proteins are analytically separated. However, due to various protein structures (e.g., glycosylation) the affinity to the dye is inconsistent. A direct correlation between measured band intensity and protein concentration and, therefore, absolute protein quantification is not possible. The purpose of this study was to apply a novel stain free SDS-PAGE technique that relies on measuring UV light fluorescence of tryptophan in order to quantify MFGM proteins. Thus, proteins can be quantified without the need for analytical standards, provided that the relative tryptophan content relative to the molecular weight is known. In this study, buttermilk and butter serum obtained from raw cream were examined and the three most abundant membrane proteins were absolutely quantified. Higher amounts of peripheral MFGM proteins were determined in buttermilk (0.9 g/L) and butter serum (2.7 g/L), in comparison to integral MFGM proteins (0.3–0.5 g/L). Conclusions were drawn regarding the absolute protein amount of MFGM material surrounding native milk fat globules. [ABSTRACT FROM AUTHOR]

Dietary proteins play important roles in the growth and reproduction of sheep, and the ewe's demand for proteins increases dramatically during late pregnancy. This research aimed to investigate the effect of dietary crude protein (CP) levels during late pregnancy on colostrum fat globule membrane (MFGM) protein and the growth performance of Hu sheep and their offspring, and provide a reference for the protein intake of ewes during late pregnancy. A total of 108 multiparous Hu sheep (45.6 ± 1.18 kg) were selected for this study, then 60 pregnant ewes confirmed by B-scan ultrasonography were randomly divided into three treatments (20 ewes/treatment) and fed by total mixed ration pellet with CP levels at 9.00% (LP), 12.0% (MP), and 15.0% (HP) during late pregnancy, respectively. The weight and dry matter intake of ewes during late pregnancy were recorded to calculate the average daily gain (ADG) and feed conversion ratio (FCR). Twin lambs were weighed on days 0, 7, 14, 30, 60, and 180 after birth to calculate ADG. Meanwhile, the colostrum of ewes was collected within 12 h after delivery. The colostrum MFGM proteins were identified and quantified by the isobaric tag for relative and absolute quantification (iTRAQ) coupled with liquid chromatography-tandem mass spectrometry methods. In addition, biological functions of differentially expressed proteins (DEPs) were annotated by Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The results revealed that a 15.0% CP level had significant effects on the BW of lambs on days 0, 7, and 30 ( P < 0.05). Notably, a total of 1,529 MFGM proteins were identified and 286 DEPs were found among three treatments. Functional analysis showed that DEPs were mainly involved in cell growth, differentiation, and tissue repair, and involved in metabolic pathways, such as the porphyrin and chlorophyll metabolism pathways. In this study, lambs in HP treatment had better growth performance; moreover, dietary 15.0% CP level also affected the colostrum MFGM proteins composition of Hu ewes. These observations can facilitate future studies on the feeding regimen of ewes during late pregnancy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wang, Zhang, Li and Yue.)

Milk fat is dispersed in milk as small, spherical globules, stabilized in the form of emulsion by its surrounding membrane. This membrane, called the milk fat globule membrane (MFGM), is created in the secretory cells of the mammary gland, and represents an ordered and unique biophysical system. This review characterizes the main milk fat globule components, their structure, and intracellular origin. The milk fat globule membrane has many potentially bioactive components. These are discussed in terms of their health effects for the native and processed globules. Because of their functional and nutritional properties, MFGM components can be used as valuable ingredients in the manufacture of new functional foods. [ABSTRACT FROM PUBLISHER]

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]

Churning is a common method to separate milk fat globule membrane (MFGM) from milk fat globules. In this work, we qualitatively and relative quantitatively analyzed the MFGM components obtained by churning cream for different time using a label-free proteomic approach. The result showed that 794 MFGM proteins were identified in all groups, of which 51, 14, 60 and 44 unique proteins were contained after churning cream for 2 min, 4 min, 6 min and 8 min, respectively. The sample churned for 6 min possessed the largest portion of total and unique proteins compared with other three groups. The relative abundances of proteins butyrophilin and xanthine dehydrogenase/oxidase, proteins cluster of differentiation 36 and fatty acid binding protein had the same change tendency during the continuous agitation process. Some milk serum proteins also were detected in the buttermilk. The analysis of protein profiles of MFGM at different churning time had an important guidance for enriching a certain MFGM protein. • MFGM enriched materials were obtained by churning cream for different time. • Distribution of MFGM proteins was analyzed by proteomic approach. • BTN can be obtained from the buttermilk by churning for 6min. • PAS6/7 can be obtained from the buttermilk by churning for 8min. [ABSTRACT FROM AUTHOR]

Homogenization disrupts fat globules and reduces the size of fat globules. This processing method changes the components of milk fat globule membranes (MFGMs). In this work, changes in the MFGM protein profile, namely, the amount and number of proteins, of pasteurized milk caused by different homogenization conditions, including preheating temperature (prior to homogenization) and pressure, were investigated using a label-free proteomic approach, Kjeldahl nitrogen determination and SDS-PAGE. In total, 467 MFGM proteins in all the samples were identified. When the homogenization pressure was 30 MPa or the preheating temperature was 60 °C, the number of MFGM proteins was the highest. Preheating treatment caused a decrease in MFGM proteins. In raw milk, SDS-PAGE revealed the incorporation of MFGM proteins, such as XO, BTN, and ADPH, through disulphide bonds with the surface of the MFGM. In addition, the amount of β-CN and α-La increased with increasing homogenization pressure and preheating temperature, respectively. The two treatments also reduced the amount of CD 36, FABP, and PAS 6/7 that were involved in the reconstruction of MFGMs to some extent. • Homogenization can induce diverse types of proteins involved in MFGM reconstruction. • Preheating treatment caused a decrease in the number of MFGM proteins. • This research method could be extended to MFGM reconstruction in other milk products. [ABSTRACT FROM AUTHOR]