Fat Globule Membrane Material Research Articles

Effect of the addition of milk fat globule membrane materials to the construction of fat globule interface in infant formula

To investigate whether the addition of milk fat globule membrane (MFGM) materials could improve the fat stability of infant formula and study the mechanism of membrane construction of fat globules, MFGM materials were added to infant formula in raw materials. The results showed that the optimal additional amount of MFGM materials was 0.5% to achieve better fat stability in the infant formula. The concentration of interfacial proteins in the reconstituted milk‐added MFGM materials was higher than in the control sample. Moreover, the laser confocal scanning microscopy image showed that MFGM materials were involved in the membrane construction of fat globules.

Emulsification potential of milk fat globule membrane material microfiltrated from buttermilk whey

The emulsification potential of milk fat globule membrane (MFGM) material obtained from buttermilk whey was investigated. A microfiltration technique was applied to recover MFGM material from the whey, a side-stream of the cheese-making process from the buttermilk. During the preparation of O/W emulsions, a constant ratio of protein and oil was maintained, and homogenised at 0/2, 3/2, 9/2, and 15/2 MPa pressures using a two-step homogeniser. Emulsions prepared with buttermilk powder (BMP) and microfiltrated buttermilk whey (MFBMW) showed similar microstructure and rheological properties. The particle distribution and mean diameter (D3,2) were similar for both materials. However, no cream separation was observed for emulsion prepared with MFBMW during 8-day storage. Despite the differences in the composition, MFBMW showed good creaming stability, and similar emulsifying properties to BMP. These results demonstrated the future perspective of whey valorisation in a high food value dairy application.

Stabilization of human milk fat analog emulsions using milk fat globule membrane material–coated lipid droplets: Structural and physical properties

To mimic the human milk fat globule, milk fat globule membrane (MFGM) was used as an emulsifier to coat the lipid droplets for the preparation of the human milk fat analog emulsions (MFEs). The physical properties of MFEs at different pH and ionic strength and digestion properties were evaluated. The results showed that the encapsulation rate of MFEs was more than 90%, and the zeta potential was −18.53 mV. MFGM fragments were adsorbed at the interface of the lipid droplets and remained stably dispersed in the aqueous phase. Aggregation of MFEs occurred at pH of 3.5–5.3 and NaCl ≥50 mM or CaCl2 ≥ 5 mM. MFEs behaved as viscoelastic liquids at a pH < 6.7 and aggregated at a pH < 4.6, thus forming a gel with increased viscosity. In addition, the digestive characteristics of MFEs were closer to that of human milk. Lipid droplets aggregated during the gastric digestion stage; however, some parts of the globule structure remained until the end of the intestinal digestion stage. This study provides a better understanding of emulsifying and digestive properties of MFGM, and MFGM can be exploited to develop emulsions containing MFGM-coated lipid droplets for the design of infant food.

Effects of egg yolk lecithin/milk fat globule membrane material ratio on the structure and stability of oil-in-water emulsions

The stability and structure of fat globules are crucial factors affecting the stability of fat in infant formulas and their inherent digestibility and absorption in infants. Thus, the study of mimicking milk fat globule (MFG) emulsions can provide a foundation for the optimization of fats in infant formulas. This study examined the effects of the ratio of egg yolk lecithin (EYL) to milk fat globule membrane (MFGM) material on the stability and fat globule structure of the emulsions. The results show a 1:1 ratio of EYL to MFGM material led to an emulsion with the highest encapsulation rate (90.07 ± 1.03%) and physical stability, larger particle size (1.514 ± 0.043 μm), and the most uniform distribution. Interestingly, formulation at a 1:1 ratio also resulted in the formation of MFG-like structures with phospholipids and proteins encapsulating the lipid core. Moreover, as the ratio of EYL to MFGM material increased, the casein and whey protein content at the simulated fat globule interface decreased, while the phospholipid content increased. Therefore, the addition of EYL represents a promising strategy to enhance the fat globule structure of the MFGM material and increase the stability of the emulsion.

Comparison of bovine milk fat globule membrane protein retention by different ultrafiltration membranes using a label-free proteomic approach

Ultrafiltration (UF) is an effective method for separating and enriching milk proteins. This study aims to analyze the protein profile of milk fat globule membrane (MFGM) materials enriched by UF membranes from butter serum with different molecular mass cutoffs through a label-free proteomic approach. In total, 616 MFGM proteins were identified in all groups, of which 395, 399, 399 and 484 proteins were identified with a 30 kDa, 50 kDa and 100 kDa UF membrane and without UF, respectively. It was more efficient to enrich fatty acid binding protein and mucin 15 using a 30 kDa membrane, whereas mucin 1 was more abundant when using a 50 kDa membrane. Compared with the 30 kDa and 50 kDa membranes, the 100 kDa membrane led to the optimal efficiency with low permeation of the most major MFGM proteins and high permeation of non-MFGM proteins. Butyrophilin, adipophilin, xanthine oxidase/dehydrogenase, and periodic acid Shiff6/7 were concentrated approximately twofold in the 100 kDa retentate. Meanwhile, the relative abundances of β-lactoglobulin and α-lactalbumin were reduced by approximately 17.3% and 16.2%, respectively. This work will facilitate the development of MFGM protein isolation using membrane separation processes and provide a theoretical reference for the production of MFGM proteins.

Emulsification and dilatational surface rheology of ultrasonicated milk fat globule membrane (MFGM) materials

Herein milk fat model emulsions (MFMEs) of infant formulas were prepared with ultrasonication-processed milk fat globule membrane (MFGM) materials (as well as MFGM/Lecithin blend and lecithin). The emulsion stability during storage was determined with a turbiscan. The microstructure of MFMEs was examined with confocal laser scanning microscopy (CLSM) at different pH values. Besides, the adsorption kinetics and linear/nonlinear dilatational rheological properties of oil/water interfaces were measured with a droplet tensiometer. After ultrasonication process, the average particle size of MFGM fragments decreased from 800 ± 100 nm to 230 ± 10 nm. The surface tension (at 100 s) of MFGM-stabilized interfaces was 17.4 mN/m (0.5 g/L), 12.9 mN/m (1.0 g/L and 2.0 g/L) and 11.0 mN/m (4.0 g/L), indicating a good emulsifying capacity of ultrasonicated MFGM materials. At neutral and acidic pH, MFMEs stabilized with MFGM dispersions or MFGM/Lecithin (1:1) at a total concentration of 4.0 g/L showed strong resistance against coalescence (CLSM). MFGM dispersions exhibited different surface rheological behaviour from pure phospholipids, proteins or a simple phospholipid/protein mixture, which suggested a heterogeneous structure of MFGM-stabilized interfaces, mainly consisting of MFGM fragment particles, interspersed with free phospholipids and proteins. These findings could provide a better understanding of emulsifying properties of MFGM materials.

Effect of milk fat globule membrane materials on the crystallization behaviour in dairy recombined cream

Milk fat globule membrane (MFGM) fragments were isolated from reconstituted buttermilk (BM-MFGM) and from buttermilk whey (whey-MFGM) and used to make recombined cream. Besides, the commercial dairy ingredient, Lacprodan® PL20, a material rich in milk polar lipids and proteins, was used as another MFGM source. Recombined cream was prepared by homogenizing 35% (w/w) anhydrous milk fat into an aqueous phase containing individual BM-MFGM, Whey-MFGM, Lacprodan® PL20, or buttermilk powder (BMP) or a mixture of MFGM materials and BMP (4:6, w/w). The effect of MFGM on the fat crystallization behaviour, shear-induced partial coalescence was investigated and compared to those of natural cream and recombined cream made with BMP. It was found that the physicochemical properties of recombined cream were strongly affected by the MFGM source. Shear-induced partial coalescence of WheyMFGM40 was slower compared to that of natural cream. Amongst the four emulsifier materials used in this study, Whey-MFGM showed a similar crystallization behaviour to natural cream.

Microfiltration of raw milk for production of high-purity milk fat globule membrane material

Commercial ingredients containing milk fat globule membrane (MFGM) material are currently isolated from heavily processed dairy streams. The aim of this study was to achieve a more gentle isolation of MFGM material by means of ceramic dia-microfiltration of raw whole milk to separate fat globules from casein micelles and whey proteins prior to MFGM extraction. A pilot-scale experiment with 1.4 μm pore size (membrane surface area 1.05 m2) resulted in an optimal outcome of low permeation of fat (2.5% permeation) and high permeation of proteins (97% permeation). This yielded an MFGM isolate with 7% w/w polar lipids and 30% w/w proteins, where contamination of non-MFGM proteins was only 25% of total protein content. Furthermore, mild pasteurization (72 °C, 15 s) introduced either before or after microfiltration had no impact on filtration efficiency or MFGM yield and composition. The work describes an industrially relevant production method for a less-processed MFGM material of high purity with potential for further separation and valorisation of protein-rich permeate streams.

Placing pasteurisation before or after microfiltration impacts the protein composition of milk fat globule membrane material

Milk fat globule membrane (MFGM) is a value-added ingredient with numerous applications. During industrial isolation, the choice of processing steps is known to influence the intactness and bioactivity of the resulting MFGM-containing material. The present study demonstrates that pasteurisation at 80, 85 or 88 °C had a different impact on the protein composition of MFGM material, depending on whether it was performed before or after microfiltration of raw milk. MFGM isolates from milk pasteurised before microfiltration had a significantly higher content of β-lactoglobulin, but a lower level of periodic acid Schiff base 6 and 7, compared with MFGM isolated from milk pasteurised after microfiltration. The β-lactoglobulin content in MFGM material increased progressively with pasteurisation temperatures. Pasteurisation after filtration did not alter the protein composition of MFGM material significantly compared with an unpasteurised control. The results point towards improved process requirements for a more gentle isolation process for MFGM-enriched fractions.

Rheological Characteristics of Yoghurt with Varying Levels of Milk Fat Globule Membrane

The study on the potential applications of milk fat globule membrane (MFGM) material as an ingredient in processed food has become of great interest in the dairy industry today due to the functional and bioactive properties it possessed. Here, we investigated the effects of varying concentrations of MFGM material isolated from butter milk on the rheological properties of yoghurt. Based on the results, the enrichment of MFGM materials significantly affected the rheological properties of yoghurt. Yoghurts enriched with buttermilk MFGM materials showed shear thinning behavior which was higher than the control. They exhibited a thixotropic behavior as well, as the viscosity of yoghurts enriched with buttermilk MFGM material decreased when subjected to increasing shear rate. The enrichment of higher concentrations of MFGM material isolated from buttermilk produced a gel with high initial apparent viscosity but collapsed rapidly when shear was applied; but still the final viscosity was higher than control. Further investigation should be done on the effects of MFGM materials on the properties of yoghurt. An oxidative stability study on the MFGM enriched yoghurt should be conducted. Duration of experimental conduct such as on the storage time can be lengthened to provide a clearer picture on the evolution of yoghurt gel during storage. Study on the effects of MFGM materials at various pasteurization temperature-time, and different incubation temperature-time combinations should be looked into.

Lipid droplets coated with milk fat globule membrane fragments: Microstructure and functional properties as a function of pH

Processed lipid droplets coated by milk fat globule membrane (MFGM) material are of primary interest to mimic the specific functions provided by the fat globules in milk and dairy products. The objectives were to investigate, as a function of pH, the properties and microstructure of MFGM-coated lipid droplets prepared with an ingredient rich in MFGM containing polar lipids and proteins. The samples were prepared in water and in milk ultrafiltrate. The combination of microscopy techniques, zeta potential and particle size measurements, and rheological determinations was used. We showed that all the components of the ingredient were highly sensitive to pH. Both the polar lipids and proteins contributed to the isoelectric point of the MFGM-rich ingredient at pI=4.2. Lipid droplets were coated with MFGM fragments both adsorbed at the surface of fat and protruding in the aqueous phase. Below pH5.5 the microstructure of the emulsions was affected by aggregation of the lipid droplets and formation of a gel. The emulsions prepared in water did not show coalescence upon 30days storage, while those prepared in milk ultrafiltrate showed coalescence for pH below 5.5. This study demonstrates that the MFGM-rich ingredient has excellent emulsifying properties and will contribute in the development of emulsions containing MFGM-coated lipid droplets for techno-functional, nutritional and health benefits (e.g. in infant formulas).

Isolation of milk fat globule membrane (MFGM) material by coagulation and diafiltration of buttermilk

Due to the functional potential of milk fat globule membrane (MFGM), its isolation from buttermilk is receiving increasing attention by the food industry. However, extraction of MFGM proteins from buttermilk is challenging because of the high levels of serum proteins. In this study, a two-step approach was applied to obtain a MFGM isolate. First, native casein micelles from buttermilk were removed by rennet-induced coagulation. Next, the buttermilk whey obtained was filtered to remove the residual whey proteins. Purified MFGM isolate was collected after six diafiltration steps. The yield of MFGM proteins in the isolates was determined using sodium dodecylsulphate-polyacrylamide gel electrophoresis. In the MFGM isolates, 70% of peripheral membrane proteins were obtained, which is much more effective in comparison with recent isolation methods like cream washing or filtration of buttermilk. Further investigations on casein coagulation conditions of buttermilk may reduce losses, especially of integral MFGM proteins during renneting.

Combined effects of milk fat globule membrane polar lipids and protein concentrate on the stability of oil-in-water emulsions

Milk fat globule membrane (MFGM) material isolated from reconstituted buttermilk by microfiltration (i.e., whole MFGM) contains two major fractions, namely proteins (consisting mainly of MFGM-specific proteins and serum proteins) and lipids (original membrane polar lipids and contaminating triglycerides from the globule core). In this study, MFGM proteins and polar lipid (PL) concentrate were separated from whole MFGM material using solvent extraction. The particle size distribution, stability, surface protein and polar lipid load of oil-in-water emulsions prepared with protein or PL concentrate, individually or in combination, at various concentrations were examined. At low emulsifier concentrations (<2.3%), there was an interacting effect between proteins and PLs on the droplet size. The phase separation of emulsions prepared with a combination of 0.3% proteins and 0.3% PLs was similar to that of emulsions containing 0.3% proteins. The proteins were more preferentially adsorbed at the emulsion droplet surface compared with PLs.

Comparison of emulsifying properties of milk fat globule membrane materials isolated from different dairy by-products

Emulsifying properties of milk fat globule membrane (MFGM) materials isolated from reconstituted buttermilk (BM; i.e., BM-MFGM) and BM whey (i.e., whey-MFGM), individually or in mixtures with BM powder (BMP) were compared with those of a commercial dairy ingredient (Lacprodan PL-20; Arla Foods Ingredients Group P/S, Viby, Denmark), a material rich in milk polar lipids and proteins. The particle size distribution, viscosity, interfacial protein, and polar lipids load of oil-in-water emulsions prepared using soybean oil were examined. Pronounced droplet aggregation was observed with emulsions stabilized with whey-MFGM or with a mixture of whey-MFGM and BMP. No aggregation was observed for emulsions stabilized with BM-MFGM, Lacprodan PL-20, or a mixture of BM-MFGM and BMP. The surface protein load and polar lipids load were lowest in emulsions with BM-MFGM. The highest protein load and polar lipids load were observed for emulsions made with a mixture of whey-MFGM and BMP. The differences in composition of MFGM materials, such as in whey proteins, caseins, MFGM-specific proteins, polar lipids, minerals, and especially their possible interactions determine their emulsifying properties.

The influence of fat globule membrane material on the microstructure of low-fat Cheddar cheese

Microstructural characteristics of low-fat Cheddar cheese differing in the content of milk fat globule membrane (MFGM) material achieved by addition of either buttermilk powder (BMP) or skim milk powder (SMP) to the cheese milk were investigated. Scanning electron microscopy and confocal scanning laser microscopy were used to study the cheese structure and the distribution of the starter culture and fat globules. Variations in the microstructure were observed relating to the MFGM content. The structure of the control cheese (made with the addition of SMP) was more irregular with inhomogeneous large voids. In contrast, cheese made with BMP addition had a homogeneous protein network with small voids, showing a smoother, more compact and less coarse structure accompanied by more pronounced fat globules that were uniformly scattered throughout the protein matrix. The starter bacteria were located within the protein networks in clusters that were distributed homogeneously throughout the cheese matrix regardless of treatment.

Physical properties and microstructure of yoghurt enriched with milk fat globule membrane material

Milk fat globule membrane (MFGM) material was isolated from industrial buttermilk powder (BMP) and both were used as a supplement for the production of yoghurt. MFGM isolated from BMP contained a high concentration of skim milk proteins. The pH measurements indicated no retardation effect of MFGM material to yoghurt fermentation. Comparing yoghurts with the same amount of dry solids, an increase in the concentration of MFGM-enriched material resulted in increasing water-holding capacity and adhesiveness. Supplementation of the MFGM material altered the firmness of yoghurt. Based on confocal laser scanning microscopy, the microstructure of MFGM-enriched yoghurts was denser from that of plain skim milk and BMP-enriched yoghurts. These results indicate the high potential of MFGM material to be used as a novel ingredient for the development of new functional products, utilizing both the technological functionalities as well as the nutritional properties of the material.

Long term effects on human plasma lipoproteins of a formulation enriched in butter milk polar lipid

BackgroundSphingolipids (SL), in particular sphingomyelin (SM) are important components of milk fat polar lipids. Dietary SM inhibits cholesterol absorption in rats (Nyberg et al. J Nutr Biochem. 2000) and SLs decrease both cholesterol and TG concentrations in lipid- and cholesterol fed APOE*3Leiden mice (Duivenvoorden et al. Am J Clin Nutr. 2006). This human study examines effects of a butter milk formulation enriched in milk fat globule membrane material, and thereby in SLs, on blood lipids in healthy volunteers. In a four week parallel group study with 33 men and 15 women we examined the effects of an SL-enriched butter milk formulation (A) and an equivalent control formulation (B) on plasma lipid levels. Plasma concentrations of HDL and LDL cholesterol, triacylglycerols (TG), apolipoproteins AI and B, and lipoprotein (a) were measured. The daily dose of SL in A was 975 mg of which 700 mg was SM. The participants registered food and drink intake four days before introducing the test formula and the last four days of the test period.ResultsA daily increase of SL intake did not significantly influence fasting plasma lipids or lipoproteins. In group B TG, cholesterol, LDL, HDL and apolipoprotein B concentrations increased, however, but not in group A after four weeks. The difference in LDL cholesterol was seen primarily in women and difference in TG primarily in men. No significant side effects were observed.ConclusionThe study did not show any significant decrease on plasma lipids or lipoprotein levels of an SL-enriched formulation containing 2-3 times more SL than the normal dietary intake on cholesterol, other plasma lipids or on energy intake. The formulation A may, however, have counteracted the trend towards increased blood lipid concentrations caused by increased energy intake that was seen with the B formulation.

The properties of liposomes produced from milk fat globule membrane material using different techniques

The isolation of milk fat globule membrane (MFGM) material from buttermilk on a commercial scale has provided a new ingredient rich in phospholipids and sphingolipids. In the pharmaceutical and cosmetic industries, highly purified phospholipids extracted from soya oil or egg yolk are used to produce liposomes. Liposomes are spherical structures consisting of one or more phospholipid bilayers enclosing an aqueous core. They may be used for the entrapment and controlled release of drugs or nutraceuticals, as model membranes or cells, and even for specialist techniques such as gene delivery. There are many potential applications for liposomes in the food industry, ranging from the protection of sensitive ingredients to increasing the efficacy of food addi- tives. Our previous work compared the structure and properties of liposomes prepared from a milk fat globule membrane (MFGM) fraction and soya phospholipid material using a high-pressure ho- mogenizer (Microfluidizer). These results identified some potential advantages in the use of MFGM phospholipids for the manufacture of liposomes for use in food systems. This paper compared the general structure and properties of liposomes prepared from the same MFGM phospholipid mate- rial using three different techniques - microfluidization, the traditional thin-film hydration and the heating method. The thin-film hydration technique required the use of organic solvents, while the other two methods do not involve any non food-safe chemicals. The liposomes prepared by both microfluidization and the heating method had high entrapment efficiencies. Liposomes produced via microfluidization tended to be significantly smaller than those produced by the other methods, with a narrower size distribution, and a higher proportion of unilamellar vesicles. There did not seem to be any advantages in the use of the thin-film hydration method, opening the door to the use of food-safe methods for liposome production. liposome / milk fat globule membrane / phospholipid / microfluidization

Development of the milk fat microstructure during the manufacture and ripening of Emmental cheese observed by confocal laser scanning microscopy

Changes in the physico-chemical properties and microstructure of milk fat globules were investigated during the manufacture and ripening of Emmental cheese. The measurement of fat globule size and apparent zeta-potential showed that they were slightly affected during cheese milk preparation, i.e. storage of cheese milk overnight at 4 °C and pasteurisation. After rennet-induced coagulation and heating of curd grains, coalescence caused the formation of large fat globules (i.e.>10 μm). The structure of fat in Emmental cheese was characterised in situ using confocal laser scanning microscopy (CLSM). The rennet-induced coagulation lead to the formation of a continuous network of casein strands in which fat globules of various sizes were entrapped. Heating of curd grains induced the formation of fat globule aggregates. Pressing of the curd grains resulted in the greatest disruption of milk fat globules, their coalescence, the formation of non-globular fat (free fat) and the release of the milk fat globule membrane (MFGM) material. This study showed that milk fat exists in three main forms in ripened Emmental cheese: (i) small fat globules enveloped by the MFGM; (ii) aggregates of partially disrupted fat globules and (iii) free fat, resulting from the disruption of the MFGM and allowing free triacylglycerols to fill voids in the protein matrix. The curd grain junctions formed in Emmental cheese were also characterised using CLSM: they are compact structures, rich in protein and devoid of fat globules.

Preparation of Liposomes from Milk Fat Globule Membrane Phospholipids Using a Microfluidizer

The isolation of milk fat globule membrane (MFGM) material from buttermilk on a commercial scale has provided a new ingredient rich in phospholipids and sphingolipids. An MFGM-derived phospholipid fraction was used to produce liposomes via a high-pressure homogenizer (Microfluidizer). This technique does not require the use of solvents or detergents, and is suitable for use in the food industry. The liposome dispersion had an average hydrodynamic diameter of 95nm, with a broad particle-size distribution. Increasing the number of passes through the Microfluidizer, increasing the pressure, or reducing the phospholipid concentration all resulted in a smaller average liposome diameter. Changing these variables did not have a significant effect on the polydispersity of the dispersion. Electron microscopy showed that the dispersions formed had a range of structures, including unilamellar, multilamellar, and multivesicular liposomes. The composition of the MFGM phospholipid material is different from that of the phospholipids usually used for liposome production in the pharmaceutical and cosmetic industries. The MFGM-derived fraction comprises approximately 25% sphingomyelin, and the fatty acids are primarily saturated and monounsaturated. These differences are likely to affect the properties of the liposomes produced from the phospholipid material, and it may be possible to exploit the unique composition of the MFGM phospholipid fraction in the delivery of bioactive ingredients in functional foods.