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Christelle Lopez - One of the best experts on this subject based on the ideXlab platform.

  • The interfacial properties of Milk Fat Globules govern their interactions with proteins: role of high shear stress and pH probed by AFM based force spectroscopy
    2019
    Co-Authors: Sameh Obeid, Nadine Leconte, Frederic Gaucheron, Fanny Guyomarc'h, Grégory Francius, Herve Guillemin, Stéphane Pezennec, Gaelle Tanguy-sai, Christelle Lopez
    Abstract:

    The interfacial properties of colloidal particles influence their interaction with each other and with their environment. This, in turn, governs the physical and functional characteristics of colloidal systems such as emulsions found in foods, drugs or cosmetics. Milk has been an important part of the human diet for thousands of years. It is a natural oil-in-water emulsion in which the lipids are dispersed as ~0.1-10 μm colloidal assemblies called the Milk Fat Globules (MFG). MFG are composed of a core droplet of triacylglycerols (TAG) surrounded by a biological membrane. This membrane, mainly composed of polar lipids, cholesterol and glycoproteins, acts as the interface with the surrounding bulk of Milk proteins (ie. casein micelles and whey proteins) or with enzymes of the gastrointestinal tract during digestion. The physicochemical properties of MFG and their membrane composition are altered by technological treatments during the manufacture of dairy products (Lopez et al., 2015, Dairy Science & Technology). Shear stress induces the adsorption of caseins from the aqueous phase of Milk to the MFG surface and heat-treatment causes the co-adsorption of highly-reactive denatured whey proteins. All these proteins precipitate at acid pH, which is used for Milk gelation in yoghurt-making. Here, atomic force spectroscopy was used to measure the adhesion forces, adhesion work and rupture distances between individual casein micelles, attached to the AFM probe, and MFG taken at different stages of processing: native MFG, then processed MFG, prior to and after acidification. Results showed that native MFG present low affinity for casein micelles independently of the pH, due to the steric effect of the glycocalyx surrounding their native membrane. When casein were adsorbed to the MFG’s surface, the adhesion forces increased, particularly at acid pH due to a decrease in electrostatic repulsion. The presence of denatured whey proteins further enhanced adhesion between the MFG and individual casein micelles. These results evidenced a clear correlation between adhesion forces at the nanoscale and the bulk properties of the Milk gels. This showed that the interfacial properties of MFG are important to drive the connectivity of the acid gel. This study open perspectives for the closer evaluation of individual colloid interface properties in relationship with the bulk physical and functional properties of colloid systems.

  • The surface properties of Milk Fat Globules govern their interactions with the caseins: Role of homogenization and pH probed by AFM force spectroscopy
    Colloids and Surfaces B: Biointerfaces, 2019
    Co-Authors: Sameh Obeid, Frederic Gaucheron, Marie-hélène Famelart, Fanny Guyomarc'h, Grégory Francius, Herve Guillemin, Stéphane Pezennec, Chantal Cauty, Christelle Lopez
    Abstract:

    The surface of Milk Fat Globules consists of a biological membrane rich in polar lipids and glycoproteins. However, high shear stress applied upon homogenization disrupts the membrane and leads to the adsorption of casein micelles, as the major protein fraction of Milk. These changes in the interface properties could affect the interactions between native or homogenized Milk Fat Globules and the surrounding protein matrix, at neutral pH and upon acidification. In this study, macroscale rheometry, microscopic observations, nanoscale AFM-based force spectroscopy and physico-chemical analysis were combined to examine the interfacial composition and structure of Milk Fat Globules and to evaluate their interactions with casein micelles. We showed that the surface properties of Milk Fat Globules (biological membrane vs. caseins) and pH govern their interactions with casein micelles. The adhesion between individual Fat Globules and casein micelles was higher upon homogenization, especially at acid pH where the work of adhesion increased from 3.3 x 10-18 to 14 x 10-18 J for native and homogenized Fat Globules, respectively. Consequently, casein-coated homogenized Fat Globules yield stiffer Milk acid gels. These findings cast light on the importance of colloidal particle’s surface properties and pH on their connectivity with the surrounding matrix, which modulates the bulk microstructure and rheological properties with potential functional consequences, such as Milk lipid digestion.

  • Unraveling the Complexity of Milk Fat Globules to Tailor Bioinspired Emulsions Providing Health Benefits: The Key Role Played by the Biological Membrane
    European Journal of Lipid Science and Technology, 2018
    Co-Authors: Christelle Lopez, Chantal Cauty, Fanny Guyomarc'h
    Abstract:

    Many food products are oil in water (O/W) emulsions. Milk has the specificity to be a natural O/W emulsion secreted by the lactating cells. The Milk Fat Globules are recognized as being efficient conveyors of energy in the form of triacylglycerols and of bioactive molecules, specifically provided by the biological membrane, the MFGM, which is the interface with the gastrointestinal tract. However, the MFGM is altered in many processed dairy products and is currently absent from standard infant Milk formulas. The objectives of this invited article are to evaluate whether the specific composition and structure of the MFGM and Milk polar lipid assemblies, associated with their nutritional and health benefits, could be used to tailor functional emulsions bioinspired by the MFGM-coated Milk Fat Globules. Recent knowledge about the structure of the MFGM revealing the heterogeneous distribution of proteins and the formation of ordered lipid domains rich in Milk sphingomyelin and cholesterol is presented. The impacts of the unique composition and biophysical properties of Milk polar lipids on the structure and potential functions of the MFGM are highlighted. Facing the evidence of both the functional and health benefits provided by the MFGM, the preparation of MFGM-enriched ingredients from dairy products has recently attracted wide attention. The utilization of MFGM components to tailor the surface of processed lipid droplets in food emulsions and to develop new products providing health benefits is discussed.

  • Buffalo Milk Fat Globules and their biological membrane: [i]in situ[/i] structural investigations
    Food Research International, 2015
    Co-Authors: Hanh T. H. Nguyen, Eric Beaucher, Marie-noelle Madec, Lydia Ong, Sally L Gras, Sandra Kendish, Christelle Lopez
    Abstract:

    Milk Fat Globules and their surrounding biological membrane (the MFGM) are not well understood despite the importance of theseMilk components in human nutrition and the role of Fat Globules in determining the properties of dairy products. The objectives of this study were to investigate these unique colloidal assemblies and the microstructure of the MFGM in buffalo Milk, which is the second largest global source of dairy products. In-situ structural investigations were performed at roomtemperature using confocalmicroscopy withmultiple fluorescent probes (Nile Red, Rh-DOPE, the lectinWGA-488). Microscopic observations showed cytoplasmic crescents around Fat Globules and the heterogeneous distribution of glycosylatedmolecules and polar lipidswith the occurrence of lipid domains. The lipid domains in the buffaloMFGMappear to formby the segregation of lipids with a high phase transition temperature (e.g. sphingomyelin and saturated phosphatidylcholine molecular species) and cholesterol resulting in a gel phase or a Lo phase forming circular domains. The structure of the buffalo MFGM results from a non-random mixing of components, consistent with observations for other species. Structural heterogeneities of theMFGMcould affect the processability of buffalo Fat Globules and the bioavailability of Milk lipids.

  • The size and interfacial composition of Milk Fat Globules are key factors controlling triglycerides bioavailability in simulated human gastro-duodenal digestion
    Food Hydrocolloids, 2014
    Co-Authors: Cyrielle Garcia, Benoît Robert, Christelle Lopez, Claudine Antona, Martine Armand
    Abstract:

    Lipids organisation might modulate Fatty acid bioavailability leading to health implications. We determined whether the size and the interfacial composition of cow Milk Fat Globules could affect triglycerides digestibility. Native Fat Globules of various sizes covered by their biological membrane (4.2 mm, large LFG 6.6 mm, small SFG 1.7 mm) or homogenised heat-treated (0.3 mm) were digested in gastric and duodenal conditions simulating human physiology. Lipolysis extents were calculated from the amount of free Fatty acids generated, and the Fatty acid composition of the products of lipolysis was determined by GC analysis. SFG were more efficiently hydrolysed than LFG by gastric (13.3 versus 5.6%), gastric plus pancreatic (62.9 versus 48.7%) and pancreatic (79.6 versus 54.7%) lipases. A higher lipid interface area with native SFG, that might increase lipases binding sites, can explain these results. However, the homogenisation, which markedly decreases Fat globule size increasing consequently the lipid/water interface area, did not improve gastric (9%) or duodenal (64.5%) lipolysis probably due to an important change in globule surface composition (proteins versus phospholipids). Interestingly, the size of the Milk globule (SFG and HM versus NM and LFG) controls the type of the free Fatty acids generated by the human gastric lipase, palmitic versus oleic acid, suggesting a different orientation of the accessible mixed triglycerides. Moreover, the type of monoglycerides produced from SFG digestion could be less atherogenic compared to LFG. The size of Fat Globules governs gastric and duodenal lipolysis extent when the composition of the interfacial layer is appropriate. It might further control Fatty acid bioavailability impacting on gastric emptying rate via the preferential release of oleic acid, a strong stimulator of CCK.

Harjinder Singh - One of the best experts on this subject based on the ideXlab platform.

  • modification of Milk Fat Globules during processing and gastrointestinal digestion
    2020
    Co-Authors: Sophie Gallier, Harjinder Singh
    Abstract:

    Milk is an important source of nutrition in the diet of children and adults. Our understanding of the structure of the Milk Fat Globules and the effect of dairy processing on the digestion of lipids has increased over the last decades. The role of the Milk Fat globule membrane (MFGM) has moved beyond being simply a triglyceride-stabilizing membrane and is recognized for providing efficient digestion, gut maturation and protection and brain development. This chapter reviews the structure of the MFGM, the effect of processing on the structure of the Fat Globules and impact on their digestion under adult and infant conditions, and the development of emulsions mimicking the structure of Milk Fat Globules.

  • symposium review Fat Globules in Milk and their structural modifications during gastrointestinal digestion
    Journal of Dairy Science, 2019
    Co-Authors: Harjinder Singh
    Abstract:

    The Fat Globules in Milk are unique oil droplets that are stabilized by a specific and structurally complex membrane, the Milk Fat globule membrane (MFGM). In the last decade, excellent progress has been made on studying the structure of the Milk Fat Globules and the MFGM and how common processing treatments affect these structures to deliver dairy products with improved functional properties. Although the digestion of Milk Fat to deliver energy and lipid-soluble nutrients is essential for survival of the neonate, there is little understanding of the complex processes involved. The structural alterations to Fat Globules during gastrointestinal processing affect the way in which Milk Fat is digested, absorbed, and metabolized. The packaging of these Globules within the MFGM or in other forms may affect the bioaccessibility of raw or processed Milk Fat Globules; in turn, this may affect access of the gastrointestinal enzymes to the Globules and, therefore, may influence the rate and extent of lipid digestion. This review focuses on recent advances in understanding Milk Fat Globules during gastrointestinal digestion, including the effects of processing on their bioavailability and the kinetics of lipid digestion. Possible effects of the dairy matrix on lipid digestion and physiological responses are briefly described.

  • Natural and processed Milk and oil body emulsions: Bioavailability, bioaccessibility and functionality
    Food Structure, 2017
    Co-Authors: Sophie Gallier, Dennis Stanley Acton, Manohar L. Garg, Harjinder Singh
    Abstract:

    Abstract A well-studied naturally-occurring lipid structure is the oil-in-water emulsion droplet. The interfacial quality and quantity of the oil droplets play a key role in the digestion in the gut and subsequent lipid uptake and may have longer term health consequences. Studies on natural droplets, the Milk Fat Globules and the oil bodies, and the effect of processing on their structure and on their digestion are discussed. This article reviews how processing affects the structure of naturally-occurring oil droplets, how it impacts the lipid bioavailability and bioaccessibility, and highlights recent developments to mimic natural lipid emulsion functionality for infant nutrition.

  • in vivo digestion of bovine Milk Fat Globules effect of processing and interfacial structural changes ii upper digestive tract digestion
    Food Chemistry, 2013
    Co-Authors: Sophie Gallier, Paul J Moughan, Shane M Rutherfurd, Xiang Q Zhu, Harjinder Singh
    Abstract:

    Abstract The aim of this research was to study the effect of Milk processing on the in vivo upper digestive tract digestion of Milk Fat Globules. Fasted rats were serially gavaged over a 5 h period with cream from raw, pasteurised, or pasteurised and homogenised Milk. Only a few intact dietary proteins and peptides were present in the small intestinal digesta. Significantly ( P C  ⩾ 10) Fatty acids were present in the digesta of rats gavaged with raw (448 mg g −1 digesta dry matter (DDM)) and homogenised creams (528 mg g −1 DDM), as compared to pasteurised and homogenised cream (249 mg g −1 DDM). Microscopy techniques were used to investigate the structural changes during digestion. Liquid–crystalline lamellar phases surrounding the Fat Globules, Fatty acid soap crystals and lipid–mucin interactions were evident in all small intestinal digesta. Overall, the pasteurised and homogenised cream appeared to be digested to a greater extent.

  • structural changes of bovine Milk Fat Globules during in vitro digestion
    Journal of Dairy Science, 2012
    Co-Authors: Sophie Gallier, Harjinder Singh
    Abstract:

    An in vitro digestion model that simulated gastric and intestinal fasting conditions was used to monitor the physical, chemical, and structural changes of Fat Globules from raw bovine Milk. During in vitro gastric digestion, the Fat Globules were stable under low-acidic conditions. Some peptides and β-lactoglobulin were resistant to proteolysis by pepsin. Phospholipids, proteins, and peptides stabilized the Globules in the stomach model. During in vitro intestinal digestion, most of the β-lactoglobulin and residual peptides were hydrolyzed by trypsin and chymotrypsin, and the lipolytic products, released from the hydrolysis of the triglyceride core of the Globules, led to destabilization and coalescence of the Globules. By accumulating at the surface of the Fat Globules, the lipolytic products formed a lamellar phase and their solubilization by bile salts resulted in the formation of disk-shaped micelles. This study brings new interesting insights on the digestion of bovine Milk.

Xingguo Wang - One of the best experts on this subject based on the ideXlab platform.

  • effects of human caprine and bovine Milk Fat Globules on microbiota adhesion and gut microecology
    Journal of Agricultural and Food Chemistry, 2021
    Co-Authors: Yunping Yao, Xingguo Wang, Xinyun Zhou, Hadiatullah Hadiatullah, Shuo Wang
    Abstract:

    Milk Fat is an essential nutrient for infant development. The effects and mechanisms of human, caprine, and bovine Milk Fat Globules (MFGs) on the gut microbiota were investigated in this study. Human MFGs enhance the efficacy of probiotics by inhibiting pathogen function. Akkermansia and Bifidobacterium were identified as the dominant microbiota by human MFGs. Mucin and complement inhibitory proteins in human MFGs were found to inhibit different pathogens. Caprine MFGs directly promoted the colonization of probiotics and the emergence of the biomarker Allobaculum. Mucin 1 in caprine MFGs was primarily responsible for inducing probiotic adhesion. Bovine MFGs increased the abundance of Oscillospira, which reduces the risk of obesity. Due to the enrichment of cell-cell junction proteins and the lack of mucin, the regulation of gut microecology by bovine MFGs was not readily apparent. In short, this study paves the way for the development of functional infant formula.

  • dairy processing affects the gut digestion and microecology by changing the structure and composition of Milk Fat Globules
    Journal of Agricultural and Food Chemistry, 2021
    Co-Authors: Xinyun Zhou, Yunping Yao, Hadiatullah Hadiatullah, Ting Guo, Xingguo Wang
    Abstract:

    Milk Fat Globules (MFGs) are the major source of energy for infants' dietary intake. In this study, the effects of changes in the structure and composition of MFG after dairy processing on lipolysis and immune regulation were investigated. Pasteurized MFG tends to form protein aggregates to prevent lipolysis. However, the aggregate is rich in neutrophil degranulation products, which are effective in killing pathogens. Homogenized MFG has the lowest hydrolysis rate due to the reconstituted anti-lipase barrier and exposed apolipoprotein. Simultaneously, the reconstituted barrier can compensate for the lack of the complement cascade. Spray-dried MFG had the highest hydrolysis rate attributable to the disrupted MFG barrier and the release of lipoprotein lipase and endothelial lipase. The immunomodulatory properties of spray-dried MFG proteins are mainly mediated by the toll-like receptor (TLR) signaling pathway. This research provides the improvement basis of dairy processing and functional infant formulas.

  • Effects of Human, Caprine, and Bovine Milk Fat Globules on Microbiota Adhesion and Gut Microecology
    'American Chemical Society (ACS)', 2021
    Co-Authors: Yunping Yao, Xingguo Wang, Xinyun Zhou, Hadiatullah Hadiatullah, Shuo Wang
    Abstract:

    Milk Fat is an essential nutrient for infant development. The effects and mechanisms of human, caprine, and bovine Milk Fat Globules (MFGs) on the gut microbiota were investigated in this study. Human MFGs enhance the efficacy of probiotics by inhibiting pathogen function. Akkermansia and Bifidobacterium were identified as the dominant microbiota by human MFGs. Mucin and complement inhibitory proteins in human MFGs were found to inhibit different pathogens. Caprine MFGs directly promoted the colonization of probiotics and the emergence of the biomarker Allobaculum. Mucin 1 in caprine MFGs was primarily responsible for inducing probiotic adhesion. Bovine MFGs increased the abundance of Oscillospira, which reduces the risk of obesity. Due to the enrichment of cell–cell junction proteins and the lack of mucin, the regulation of gut microecology by bovine MFGs was not readily apparent. In short, this study paves the way for the development of functional infant formula

  • variation of Fat globule size and Fatty acids in human Milk in the first 30 days of lactation
    International Dairy Journal, 2020
    Co-Authors: Wendi Jiang, Qingzhe Jin, Xue Zhang, Jin Cheng, Jie Song, Wei Wei, Mingdong Dong, Xingguo Wang
    Abstract:

    Abstract Variation in human Milk Fat Globules (HMFGs) and the association with Fatty acid (FA) composition during lactation was investigated. Human Milk samples (n = 134) from six healthy Chinese mothers were collected every day between 3 and 30 days postpartum, and the size distribution of HMFGs and FA composition in samples were investigated. The results indicated that mean HMFG size increased from 3.77 ± 0.95 to 5.09 ± 0.88 μm during lactation. A significant increase was observed in the size of HMFGs and Fat content in human Milk samples from day 3 to day 10 postpartum. Colostrum samples showed higher contents of medium-chain Fatty acids, very-long-chain Fatty acids, and saturated Fatty acids than mature Milk.

  • lipid composition and structural characteristics of bovine caprine and human Milk Fat Globules
    International Dairy Journal, 2016
    Co-Authors: Yunping Yao, Xiaoqiang Zou, Guozhong Zhao, Jingying Xiang, Qingzhe Jin, Xingguo Wang
    Abstract:

    Milk Fat is widely accepted to be the major nutrient in human Milk. Commercial infant formulas are usually based on mammalian Milk such as bovine or caprine Milk, but the differences in Milk Fat Globules (MFGs) between human, bovine and caprine Milk remain unclear. We showed that saturated Fatty acid content was higher in bovine and caprine MFGs (>60%) than in human MFG ( 7 times higher than in bovine and caprine MFGs. The cholesterol content of human Milk was ∼20% higher than that of bovine and caprine Milk. Triacylglycerol molecular species and polar lipids also differed between bovine, caprine and human MFGs. Confocal laser scanning microscopy images of MFGs revealed that the shape of the liquid-ordered domains varied by species.

Sophie Gallier - One of the best experts on this subject based on the ideXlab platform.

  • modification of Milk Fat Globules during processing and gastrointestinal digestion
    2020
    Co-Authors: Sophie Gallier, Harjinder Singh
    Abstract:

    Milk is an important source of nutrition in the diet of children and adults. Our understanding of the structure of the Milk Fat Globules and the effect of dairy processing on the digestion of lipids has increased over the last decades. The role of the Milk Fat globule membrane (MFGM) has moved beyond being simply a triglyceride-stabilizing membrane and is recognized for providing efficient digestion, gut maturation and protection and brain development. This chapter reviews the structure of the MFGM, the effect of processing on the structure of the Fat Globules and impact on their digestion under adult and infant conditions, and the development of emulsions mimicking the structure of Milk Fat Globules.

  • Natural and processed Milk and oil body emulsions: Bioavailability, bioaccessibility and functionality
    Food Structure, 2017
    Co-Authors: Sophie Gallier, Dennis Stanley Acton, Manohar L. Garg, Harjinder Singh
    Abstract:

    Abstract A well-studied naturally-occurring lipid structure is the oil-in-water emulsion droplet. The interfacial quality and quantity of the oil droplets play a key role in the digestion in the gut and subsequent lipid uptake and may have longer term health consequences. Studies on natural droplets, the Milk Fat Globules and the oil bodies, and the effect of processing on their structure and on their digestion are discussed. This article reviews how processing affects the structure of naturally-occurring oil droplets, how it impacts the lipid bioavailability and bioaccessibility, and highlights recent developments to mimic natural lipid emulsion functionality for infant nutrition.

  • in vivo digestion of bovine Milk Fat Globules effect of processing and interfacial structural changes ii upper digestive tract digestion
    Food Chemistry, 2013
    Co-Authors: Sophie Gallier, Paul J Moughan, Shane M Rutherfurd, Xiang Q Zhu, Harjinder Singh
    Abstract:

    Abstract The aim of this research was to study the effect of Milk processing on the in vivo upper digestive tract digestion of Milk Fat Globules. Fasted rats were serially gavaged over a 5 h period with cream from raw, pasteurised, or pasteurised and homogenised Milk. Only a few intact dietary proteins and peptides were present in the small intestinal digesta. Significantly ( P C  ⩾ 10) Fatty acids were present in the digesta of rats gavaged with raw (448 mg g −1 digesta dry matter (DDM)) and homogenised creams (528 mg g −1 DDM), as compared to pasteurised and homogenised cream (249 mg g −1 DDM). Microscopy techniques were used to investigate the structural changes during digestion. Liquid–crystalline lamellar phases surrounding the Fat Globules, Fatty acid soap crystals and lipid–mucin interactions were evident in all small intestinal digesta. Overall, the pasteurised and homogenised cream appeared to be digested to a greater extent.

  • structural changes of bovine Milk Fat Globules during in vitro digestion
    Journal of Dairy Science, 2012
    Co-Authors: Sophie Gallier, Harjinder Singh
    Abstract:

    An in vitro digestion model that simulated gastric and intestinal fasting conditions was used to monitor the physical, chemical, and structural changes of Fat Globules from raw bovine Milk. During in vitro gastric digestion, the Fat Globules were stable under low-acidic conditions. Some peptides and β-lactoglobulin were resistant to proteolysis by pepsin. Phospholipids, proteins, and peptides stabilized the Globules in the stomach model. During in vitro intestinal digestion, most of the β-lactoglobulin and residual peptides were hydrolyzed by trypsin and chymotrypsin, and the lipolytic products, released from the hydrolysis of the triglyceride core of the Globules, led to destabilization and coalescence of the Globules. By accumulating at the surface of the Fat Globules, the lipolytic products formed a lamellar phase and their solubilization by bile salts resulted in the formation of disk-shaped micelles. This study brings new interesting insights on the digestion of bovine Milk.

  • Chemical and structural characterisation of almond oil bodies and bovine Milk Fat Globules
    Food Chemistry, 2012
    Co-Authors: Sophie Gallier, Keith C. Gordon, Harjinder Singh
    Abstract:

    Abstract Lipids in almonds are present as oil bodies in the nut. These oil bodies are surrounded by a membrane of proteins and phospholipids and are a delivery vehicle of energy in the form of triglycerides, similarly to the more studied bovine Milk Fat globule membrane. Chemical, physical and microscopic analyses revealed major differences in the composition and structure of almond oil bodies and bovine Milk Fat Globules. The lipids of both natural emulsions differed in degree of unsaturation, chain length, and class. The almond oil body membrane does not contain any cholesterol or sphingomyelin unlike the bovine Milk Fat globule membrane. Therefore, the phospholipid distribution at the surface of the oil bodies did not present any liquid-ordered domains. The membranes, a monolayer around almond oil bodies and a trilayer around bovine Fat Globules, may affect the stability of the lipid droplets in a food matrix and the way the lipids are digested.

Olivia Menard - One of the best experts on this subject based on the ideXlab platform.

  • the structure of infant formulas impacts their lipolysis proteolysis and disintegration during in vitro gastric digestion
    Food Chemistry, 2015
    Co-Authors: Claire Bourlieu, Alix De La Chevasnerie, Laura Sams, Olivia Menard, Florence Rousseau, Marie-noelle Madec
    Abstract:

    Abstract Milk lipids supply most of the calories necessary for newborn growth in maternal Milk or infant formulas. The chemical composition of infant formulas has been optimized but not the structure of the emulsion. There is still a major difference between the native emulsions of Milk Fat Globules and processed submicronic emulsions in infant formulas. This difference may modify the kinetics of digestion of emulsions in newborns and influence lipid metabolism. To check this, semi-dynamic gastric in vitro digestions were conducted on three matrices: a standardized Milk emulsion containing native Milk Fat Globules referred to as minimally-processed emulsion and two processed model infant formulas (homogenized or homogenized/pasteurized). Gastric conditions mimicked those reported in newborns. The minimally-processed emulsion was lipolyzed and proteolyzed slower than processed formulas. The difference in initial structure persisted during digestion. The surface of the droplets was the key parameter to control gastric lipolysis kinetics, the pattern of released Fatty acids and proteolysis by faster hydrolysis of adsorbed proteins.

  • Fat Globules selected from whole Milk according to their size different compositions and structure of the biomembrane revealing sphingomyelin rich domains
    Food Chemistry, 2011
    Co-Authors: Christelle Lopez, Jacques Fauquant, Nadine Leconte, Eric Beaucher, Valerie Briardbion, Olivia Menard, Florence Rousseau, Benoît Robert
    Abstract:

    Abstract Milk Fat Globules are unique delivery systems for biologically active molecules in the gastrointestinal tract. However, their properties have not yet been fully investigated. In this study, we performed a comparative analysis of the polar lipid and Fatty acid compositions of Milk Fat Globules as a function of their size and investigated the structure of the Milk Fat globule membrane (MFGM). An optimised process of microfiltration was used to select the small Milk Fat globule (SMFG; 1.6 μm) fractions and the large Milk Fat globule (LMFG; 6.6 μm) fractions from the same initial whole Milks (4.2 μm). The SMFG-fractions contained significantly (i) higher amounts of polar lipids, 8.9 ± 0.9 vs 2.7 ± 0.3 mg/g Fat for LMFG-fractions and 6.3 ± 0.5 mg/g Fat for whole Milks, (ii) lower relative proportions of phosphatidylcholine and sphingomyelin in the MFGM, (iii) higher amounts of C12:0, C14:0, C16:0, C18:1 trans , C18:2 c9 tr11, and lower amounts of C18:0 and C18:1 c9 than did LMFG-fractions and whole Milks. Whatever the size of native Milk Fat Globules, the biophysical characterisation performed in-situ , using confocal laser scanning microscopy, showed heterogeneities in the MFGM. The lateral segregation of sphingomyelin in rigid liquid-ordered domains, surrounded by the fluid matrix of glycerophospholipids in the liquid-disordered phase, was revealed. The heterogeneous distribution of glycolipids and glycoproteins was also observed in the MFGM. A new model for the structure of the MFGM is proposed and discussed. The physical, chemical and biological consequences, (i) of the differences in Milk Fat globule compositions according to their size and (ii) of the specific structure of the MFGM due to sphingomyelin remain to be elucidated.

  • human Milk Fat Globules polar lipid composition and in situ structural investigations revealing the heterogeneous distribution of proteins and the lateral segregation of sphingomyelin in the biological membrane
    Colloids and Surfaces B: Biointerfaces, 2011
    Co-Authors: Christelle Lopez, Olivia Menard
    Abstract:

    Although human Milk Fat Globules (MFG) are of primary importance since they are the exclusive lipid delivery carriers in the gastrointestinal tract of breast-fed infants, they remain the poorly understood aspect of Milk. The objectives of this study were to investigate these unique colloidal assemblies and their interfacial properties, i.e. composition and structure of their biological membrane. In mature breast Milk, MFG have a mean diameter of 4-5 microm, a surface area of about 2m(2)/g Fat and an apparent zeta potential ζ=-6.7 ± 0.5 mV at 37°C. Human MFG contain 3-4mg polar lipids/g Fat as quantified by HPLC/ELSD. The main polar lipids are sphingomyelin (SM; 36-45%, w/w), phosphatidylcholine (19-23%, w/w) and phosphatidylethanolamine (10-15%, w/w). In situ structural investigations of human MFG have been performed using light and confocal microscopy with adapted fluorescent probes, i.e. Nile Red, the extrinsic phospholipid Rh-DOPE, Fast Green and the lectin WGA-488. This study revealed a spatial heterogeneity in the human Milk Fat globule membrane (MFGM), with the lateral segregation of SM in liquid-ordered phase domains of various shapes and sizes surrounded by a liquid-disordered phase composed of the glycerophospholipids in which the proteins are dispersed. The glycocalyx formed by glycoproteins and cytoplasmic remnents have also been characterised around human MFG. A new model for the structure of the human MFGM is proposed and discussed. The unique composition and lateral organisation of the human MFGM components could be of metabolic significance and have health impact for the infants that need to be further explored.

  • buffalo vs cow Milk Fat Globules size distribution zeta potential compositions in total Fatty acids and in polar lipids from the Milk Fat globule membrane
    Food Chemistry, 2010
    Co-Authors: Olivia Menard, Valerie Briardbion, Sarfraz Ahmad, Florence Rousseau, Frederic Gaucheron, Christelle Lopez
    Abstract:

    Although buffalo Milk is the second most produced Milk in the world, and of primary nutritional importance in various parts of the world, few studies have focused on the physicochemical properties of buffalo Milk Fat Globules. This study is a comparative analysis of buffalo and cow Milk Fat Globules. The larger size of buffalo Fat Globules, 5 vs. 3.5 lm, was related to the higher amount of Fat in the buffalo Milks: 73.4 ± 9.9 vs. 41.3 ± 3.7 g/kg for cow Milk. Buffalo Milks contained significantly lower amount of polar lipids expressed per gram of lipids (0.26% vs. 0.36%), but significantly higher amount of polar lipids per litre of Milk (+26%). Buffalo and cow Milk Fat globule membranes contain the same classes of polar lipids; phosphatidylethanolamine, sphingomyelin (SM) and phosphatidylcholine (PC) being the main constituents. A significant higher percentage of PC and lower percentage of SM were found for buffalo Milks. The Fatty acid analysis revealed that saturated Fatty acids, mainly palmitic acid, trans Fatty acids, linolenic acid (x3) and conjugated linolenic acid were higher in buffalo Milk than in cow Milk. Such results will contribute to the improvement of the quality of buffalo Milk-based dairy products.