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Harjinder Singh - One of the best experts on this subject based on the ideXlab platform.
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impact of gastric coagulation on the kinetics of release of Fat Globules from milk of different species
Food & Function, 2021Co-Authors: Debashree Roy, Paul J Moughan, Harjinder SinghAbstract:The behavior of Fat Globules during the gastric digestion of raw and pasteurized cow, goat, and sheep whole milks was studied using a human gastric simulator. Microstructural and physicochemical analysis revealed that, initially, the coagulation of the milks in the human gastric simulator resulted in the majority of the milk Fat Globules being entrapped within the curd. As the digestion progressed, the proportion of Fat Globules entrapped within the aggregated protein matrix (curd) decreased; there was also some flocculation as well as coalescence of the Fat Globules within the curd. The liberation of the entrapped Fat Globules from the curd to the liquid phase of the chyme was strongly dependent on the disintegration and hydrolysis of the structured casein network. Surprisingly, the Fat Globules released (or already present) into the liquid phase of the chyme were not as extensively coalesced as those remaining within the curd. These phenomena were observed to be similar for the raw and pasteurized whole milk of all species. The pasteurized whole milks from all species formed relatively less structured coagula compared with their raw milk counterparts, leading to a greater extent of protein breakdown and, thus, higher proportions of Fat release from the pasteurized milk curds. This study provides a deeper understanding of how the curd-forming properties of different mammalian milks in the gastric environment provide controlled delivery of nutrients (such as protein and Fat).
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symposium review Fat Globules in milk and their structural modifications during gastrointestinal digestion
Journal of Dairy Science, 2019Co-Authors: Harjinder SinghAbstract: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.
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Nature's complex emulsion: The Fat Globules of milk
Food Hydrocolloids, 2017Co-Authors: Harjinder Singh, Sophie GallierAbstract:Abstract The milk Fat globule in milk represents a unique emulsion system designed by Nature to deliver energy, essential Fatty acids and lipid-soluble nutrients to the neonate. The Fat Globules range from 0.1 to 15 μm in diameter and are stabilised by milk Fat globule membrane (MFGM) which is composed of phospholipids, various glycoproteins, enzymes and cholesterol. Extensive knowledge on the intracellular origin, composition and structure of Fat Globules and MFGM has been accumulated over the last 30 years. Recently, it has been speculated that the MFGM has profound effects on the accessibility of the triglycerides for lipase-catalysed digestion. This has initiated a large number of studies on the digestion of milk Fat Globules in various dairy systems involving both in vitro and in vivo human digestion models. In addition, the identification of health-beneficial components of MFGM has led to increasing interest in developing MFGM as a food ingredient with unique functional properties and health benefits. This review focuses on recent knowledge on composition and structure of Fat Globules, the MFGM, and the behaviour of Fat Globules during gastro-intestinal digestion. MFGM ingredients and their applications are briefly discussed.
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effect of homogenization and heat treatment on the behavior of protein and Fat Globules during gastric digestion of milk
Journal of Dairy Science, 2017Co-Authors: Jian Cui, Douglas G. Dalgleish, Harjinder SinghAbstract:The effects of homogenization and heat treatment on the formation and the breakdown of clots during gastric digestion of whole milk were investigated using a human gastric simulator. Homogenization and heat treatment led to formation of coagula with fragmented and crumbled structures compared with the coagulum formed from raw whole milk, but a larger fraction of the protein and more Fat Globules were incorporated into the coagula induced by action of the milk-clotting enzyme pepsin. The Fat Globules in the whole milk appeared to be embedded in the clots as they formed. After formation of the clot, the greater numbers of pores in the structures of the clots formed with homogenized milk and heated whole milk led to greater rates of protein hydrolysis by pepsin, which resulted in faster release of Fat Globules from the clots into the digesta. Coalescence of Fat Globules occurred both in the digesta and within the protein clots no matter whether they were in homogenized or heated milk samples. The formation of clots with different structures and hence the changes in the rates of protein hydrolysis and the release of milk Fat into the digesta in the stomach provide important information for understanding the gastric emptying of milk and the potential to use this knowledge to manipulate the bioavailability of Fat and other Fat-soluble nutrients in dairy products.
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in vivo digestion of bovine milk Fat Globules effect of processing and interfacial structural changes i gastric digestion
Food Chemistry, 2013Co-Authors: Sophie Gallier, Paul J Moughan, Jack Cui, Trent D Olson, Shane M Rutherfurd, Harjinder SinghAbstract:The aim was to study the in vivo gastric digestion of Fat Globules in bovine cream from raw, pasteurised or pasteurised and homogenised milk. Fasted rats were gavaged once and chyme samples were collected after 30, 120 and 180 min post-gavage. Proteins from raw (RC) and pasteurised (PC) creams appeared to be digested faster and to a greater extent. Free Fatty acids (FAs) increased throughout the 3 h postprandial period. Short and medium chain FAs were released more rapidly than long chain FAs which were hydrolysed to a greater degree from PC. The size of the Fat Globules of all creams increased in the stomach. Protein aggregates were observed in pasteurised and homogenised cream chyme. Protrusions, probably caused by the accumulation of insoluble lipolytic products, appeared at the surface of the Globules in RC and PC chyme. Overall, PC proteins and lipids appeared to be digested to a greater extent.
Christelle Lopez - One of the best experts on this subject based on the ideXlab platform.
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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, 2019Co-Authors: Sameh Obeid, Frederic Gaucheron, Marie-hélène Famelart, Fanny Guyomarc'h, Grégory Francius, Herve Guillemin, Stéphane Pezennec, Chantal Cauty, Christelle LopezAbstract: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.
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Buffalo milk Fat Globules and their biological membrane: [i]in situ[/i] structural investigations
Food Research International, 2015Co-Authors: Hanh T. H. Nguyen, Eric Beaucher, Lydia Ong, Sally L Gras, Marie-noelle Madec, Sandra Kendish, Christelle LopezAbstract: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.
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The size and interfacial composition of milk Fat Globules are key factors controlling triglycerides bioavailability in simulated human gastro-duodenal digestion
Food Hydrocolloids, 2014Co-Authors: Cyrielle Garcia, Benoît Robert, Christelle Lopez, Claudine Antona, Martine ArmandAbstract: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.
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solid triacylglycerols within human Fat Globules β crystals with a melting point above in body temperature of infants formed upon storage of breast milk at low temperature
Food Research International, 2013Co-Authors: Valerie Briardbion, Christelle Lopez, Claudie Bourgaux, Javier PerezAbstract:Abstract Breast milk Fat Globules are the natural colloidal assemblies secreted by lactating mothers to provide dietary energy and bioactive molecules to infants. Although they are important in newborn infant nutrition, growth and health, their physical properties remain poorly known. In this study, the crystallization and melting properties of breast milk triacylglycerols (TAG; 98% of milk lipids) were investigated in Fat Globules and in anhydrous state. The thermal and structural properties of breast milk TAG were characterized by differential scanning calorimetry and synchrotron radiation X-ray diffraction, respectively. Breast milk Fat Globules have a mean diameter of 4 to 5 μm. They contain 48–57% saturated Fatty acids with 27–29% of C16:0. Storage of breast milk at 4 °C in the refrigerator leads to the crystallization of high-melting point TAG within Fat Globules in β 2L (41.7 A) lamellar structures. The final melting point of these TAG crystals, T offset = 41.1 ± 1.6 °C, is above in-body temperature of infants. Hence, the solid TAG phase could affect the mechanisms of breast milk Fat Globules digestion and absorption for T offset of β TAG crystals, by decreasing the rate of TAG hydrolysis and solubilization.
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Effect of the size and interface composition of milk Fat Globules on their in vitro digestion by the human pancreatic lipase: Native versus homogenized milk Fat Globules
Food Hydrocolloids, 2012Co-Authors: Amélie Berton, Stéphanie Rouvellac, Benoît Robert, Christelle Lopez, Florence Rousseau, Isabelle CrenonAbstract:Although the bioavailability of dietary lipids is of primary importance in human nutrition and health, the mechanisms involved in lipid digestion are not fully understood and are of growing interest. The objective of this study was to determine the effect of the size of milk Fat Globules and of the composition of their interface on the activity of the human pancreatic lipase (PL). Native milk Fat Globules of various sizes covered by their biological membrane (MFGM) and homogenized Fat Globules of various sizes covered by milk proteins were prepared from whole milk and underwent lipolysis by the human PL with colipase and bile salts. A lag phase preceding the hydrolysis of milk TAG occurred with all native milk Fat Globules samples but not with homogenized milk samples. The kinetic parameters of human PL were determined by measuring the enzyme activity either after the lag phase for native milk Fat Globules samples or immediately after the addition of the enzyme for homogenized milk samples. The catalytic efficiency of human PL is 4.6-fold higher on small (1.8 μm) than large (6.7 μm) native milk Fat Globules, related to a 3.6-fold larger available surface. Despite the 25-fold larger available surface, milk TAG from homogenized milk are only 2-fold better hydrolyzed compared to native milk Fat Globules, as a possible result of a less favourable interface covered by milk proteins. The potential mechanisms involved in native vs. homogenized milk Fat Globules digestion by the human PL are discussed. Our study highlights the crucial role of the MFGM in the efficient digestion of milk Fat Globules and brings new insight for the design of dairy products and infant formulas.
Sophie Gallier - One of the best experts on this subject based on the ideXlab platform.
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Nature's complex emulsion: The Fat Globules of milk
Food Hydrocolloids, 2017Co-Authors: Harjinder Singh, Sophie GallierAbstract:Abstract The milk Fat globule in milk represents a unique emulsion system designed by Nature to deliver energy, essential Fatty acids and lipid-soluble nutrients to the neonate. The Fat Globules range from 0.1 to 15 μm in diameter and are stabilised by milk Fat globule membrane (MFGM) which is composed of phospholipids, various glycoproteins, enzymes and cholesterol. Extensive knowledge on the intracellular origin, composition and structure of Fat Globules and MFGM has been accumulated over the last 30 years. Recently, it has been speculated that the MFGM has profound effects on the accessibility of the triglycerides for lipase-catalysed digestion. This has initiated a large number of studies on the digestion of milk Fat Globules in various dairy systems involving both in vitro and in vivo human digestion models. In addition, the identification of health-beneficial components of MFGM has led to increasing interest in developing MFGM as a food ingredient with unique functional properties and health benefits. This review focuses on recent knowledge on composition and structure of Fat Globules, the MFGM, and the behaviour of Fat Globules during gastro-intestinal digestion. MFGM ingredients and their applications are briefly discussed.
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in vivo digestion of bovine milk Fat Globules effect of processing and interfacial structural changes i gastric digestion
Food Chemistry, 2013Co-Authors: Sophie Gallier, Paul J Moughan, Jack Cui, Trent D Olson, Shane M Rutherfurd, Harjinder SinghAbstract:The aim was to study the in vivo gastric digestion of Fat Globules in bovine cream from raw, pasteurised or pasteurised and homogenised milk. Fasted rats were gavaged once and chyme samples were collected after 30, 120 and 180 min post-gavage. Proteins from raw (RC) and pasteurised (PC) creams appeared to be digested faster and to a greater extent. Free Fatty acids (FAs) increased throughout the 3 h postprandial period. Short and medium chain FAs were released more rapidly than long chain FAs which were hydrolysed to a greater degree from PC. The size of the Fat Globules of all creams increased in the stomach. Protein aggregates were observed in pasteurised and homogenised cream chyme. Protrusions, probably caused by the accumulation of insoluble lipolytic products, appeared at the surface of the Globules in RC and PC chyme. Overall, PC proteins and lipids appeared to be digested to a greater extent.
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in vivo digestion of bovine milk Fat Globules effect of processing and interfacial structural changes ii upper digestive tract digestion
Food Chemistry, 2013Co-Authors: Sophie Gallier, Paul J Moughan, Shane M Rutherfurd, Xiang Q Zhu, Harjinder SinghAbstract: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.
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structural changes of bovine milk Fat Globules during in vitro digestion
Journal of Dairy Science, 2012Co-Authors: Sophie Gallier, Harjinder SinghAbstract: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.
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Chemical and structural characterisation of almond oil bodies and bovine milk Fat Globules
Food Chemistry, 2012Co-Authors: Sophie Gallier, Keith C. Gordon, Harjinder SinghAbstract: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.
Marie-caroline Michalski - One of the best experts on this subject based on the ideXlab platform.
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Membrane phospholipids and sterols in microfiltered milk Fat Globules
European Journal of Lipid Science and Technology, 2007Co-Authors: Caroline Fauquant, Nadine Leconte, Michel Guichardant, Valérie Briard-bion, Marie-caroline MichalskiAbstract:Native milk Fat Globules of various mean diameters, ranging from d43 = 2.3 mm to 8.0 mm, were obtained using microfiltration of raw whole milk. After milk Fat globule washing, the milk Fat globule membrane (MFGM) was separated by manual churning. After total lipid extraction and separation of polar lipids, their phospholipid (PL) and sterol composition was measured using thin-layer chromatography, methyl ester analyses by gas chromatography, and gas chromatography coupled to mass spectrometry. The main PL species were phosphatidylethanolamine, phosphatidylcholine and sphingomyelin. The respective Fatty acid composition of each PL species was measured. Many different minor bioactive sterols were detected in the MFGM, e.g.lanosterol, lathosterol, desmosterol, stigmasterol and b-sitosterol. No significant differences in the PL and sterol profile were found between MFGM extracted from small and large milk Fat globule fractions.
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Functionality of smaller vs control native milk Fat Globules in Emmental cheeses manufactured with adapted technologies
Food Research International, 2007Co-Authors: Marie-caroline Michalski, Nadine Leconte, Valérie Briard-bion, Marie-hélène Famelart, Benedicte Camier, Jean-yves Gassi, Christelle LopezAbstract:Abstract Emmental cheeses were produced with control native milk Fat Globules (CFG) or smaller ones (SFG) selected from the same milk by microfiltration. Either the same regular technology was used for both cheeses (so-called SFGreg and CFGreg), or two different adapted technologies to obtain cheeses with the same moisture (so-called SFGadapt and CFGadapt). SFGreg cheeses were more humid and presented lower firmness and longness than CFGreg cheeses. Yellow index was greater for SFGadapt than CFGadapt cheeses while melting coefficient and extrusion force were similar. SFGadapt cheeses exhibited improved sensory characteristics. Stretching and elasticity increase were always greater for SFG than for the corresponding CFG cheeses; eyes were always smaller in SFG cheeses. Confocal micrographs revealed larger inclusions of non-globular Fat in CFG cheeses; there were more Fat Globules and aggregates in SFG cheeses. The ultrastructure of milk Fat played a role in the functional and sensory properties of Emmental cheese and the use of smaller native Globules may be advantageous.
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cla profile in native Fat Globules of different sizes selected from raw milk
International Dairy Journal, 2005Co-Authors: Marie-caroline Michalski, Valérie Briard, Pierre JuanedaAbstract:Abstract The CLA content and isomer profile were characterized among two subclasses of the native milk Fat Globules. The latter corresponded to two fractions obtained by a microfiltration process using Spring mixed milk, leading to small Fat Globules (SFG; d 32 ∼ 2.8 μ m ) in the microfiltrates and large ones (LFG; d 32 ∼ 5 μ m ) in the retentates. Relatively, SFG always contained more CLA than the LFG originating from the same mixed milk, though discrepancies among different milk samples were observed. The main CLA isomer was the cis -9, trans -11, the content of which tended to increase when the native milk Fat globule size decreased (from 82.2% to 87.3% of total CLA isomers). Consequently, the SFG contained less trans -12, trans -14; trans -11, trans -13; trans -11, cis -13 and trans -8, cis -10 isomers than the corresponding LFG. However, the relative variation of some isomers between small and large Fat globule from the same milk varied depending on milk origin and the potential of Fat globule fractionation for influencing the content and distribution of CLA seems to be limited.
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size distribution of Fat Globules in human colostrum breast milk and infant formula
Journal of Dairy Science, 2005Co-Authors: Marie-caroline Michalski, Valérie Briard, Françoise Michel, F Tasson, P PoulainAbstract:Only a few results are available on the size of human milk Fat Globules (MFG), despite its significance regarding Fat digestion in the infant, and no data are available at <24 h postpartum (PP). We measured the MFG size distribution in colostrum and transitional human milk in comparison with Fat Globules of mature milk and infant formula. Colostrum and transitional milk samples from 18 mothers were collected regularly during 4 d PP and compared with mature milk samples of 17 different mothers and 4 infant formulas. The size distribution was measured by laser light scattering. For further characterization, the zeta-potential of some mature MFG was measured by laser Doppler electrophoresis. The MFG diameter decreased sigmoidally in the first days. At <12 h PP, the mode diameter was 8.9 +/- 1.0 microm vs 2.8 +/-0.3 microm at 96 h PP. Thus, the surface area of MFG increased from 1.1 +/-0.3 to 5.4 +/-0.7 m2/g between colostrum and transitional milk. In mature milk, the MFG diameter was 4 microm on average and increased with advancing lactation, whereas the droplets in infant formula measured 0.4 microm. The zeta potential of mature MFG was -7.8 +/- 0.1 mV. The Fat Globules are larger in early colostrum than in transitional and mature human milk and in contrast with the small-sized Fat droplets in infant formula. Human MFG also have a low negative surface charge compared with bovine Globules. These structural differences can be of nutritional significance for the infant.
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size distribution of Fat Globules in human colostrum breast milk and infant formula
Journal of Dairy Science, 2005Co-Authors: Marie-caroline Michalski, Valérie Briard, Françoise Michel, F Tasson, P PoulainAbstract:Abstract Only a few results are available on the size of human milk Fat Globules (MFG), despite its significance regarding Fat digestion in the infant, and no data are available at μ m vs 2.8 ±0.3 μ m at 96h PP. Thus, the surface area of MFG increased from 1.1 ±0.3 to 5.4 ±0.7m 2 /g between colostrum and transitional milk. In mature milk, the MFG diameter was 4 μ m on average and increased with advancing lactation, whereas the droplets in infant formula measured 0.4 μ m. The ζ potential of mature MFG was −7.8±0.1mV. The Fat Globules are larger in early colostrum than in transitional and mature human milk and in contrast with the small-sized Fat droplets in infant formula. Human MFG also have a low negative surface charge compared with bovine Globules. These structural differences can be of nutritional significance for the infant.
Gustavo V Barbosacanovas - One of the best experts on this subject based on the ideXlab platform.
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effect of nonthermal technologies on the native size distribution of Fat Globules in bovine cheese making milk
Innovative Food Science and Emerging Technologies, 2009Co-Authors: Luis Eduardo Garciaamezquita, Gustavo V Barbosacanovas, A R Primomora, D R SepulvedaAbstract:Abstract Milk-Fat globule membranes are susceptible to damage by mechanical and thermal processes. This damage is translated into alterations of milk Fat structure and functionality of cheese-making milk. The objective of this work was to evaluate the effect of pulsed electrical fields (PEF), high hydrostatic pressure (HHP), and conventional thermal treatments on Fat globule size distribution and ζ-potential. Milk was processed by HHP at 400 and 500 MPa for 0–20 min, and with PEF at 36 kV/cm and 42 kV/cm up to 64 pulses. The ζ-potential of HHP and PEF treated milk were − 15.47 mV and − 14.63 mV respectively. HHP treatments induced Fat Globules flocculation, increasing their mass moment mean diameter. Although PEF processing did not modify the true mean diameter of MFG, it induced small Globules to clump together, causing an apparent increment in the population of larger milk-Fat Globules. Industrial relevance The market for traditional raw dairy products has increased in recent times in several regions of the world due to their unique flavor and texture attributes. However, the potential negative implications of consuming raw products limit the growth of this market segment. Manufacture of raw-like cheese from thermally pasteurized milk is not feasible, among other things, because of milk Fat globule membrane damage caused by elevated temperatures. Nonthermal food preservation technologies offer the potential to produce milk technically suitable for the industrial manufacture of microbiologically safe raw-like dairy products.
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microstructure of Fat Globules in whole milk after thermosonication treatment
Journal of Food Science, 2008Co-Authors: Daniela Bermudezaguirre, R Mawson, Gustavo V BarbosacanovasAbstract:The structure of Fat Globules in whole milk was studied after heat and thermosonication treatments to observe what happens during these processes at the microscopic level using scanning electron microscopy. Raw whole milk was thermosonicated in an ultrasonic processor-Hielscher UP400S (400 W, 24 kHz, 120 microm amplitude), using a 22-mm probe at 63 degrees C for 30 min. Heat treatment involved heating the milk at 63 degrees C for 30 min. Color and Fat content were measured to correlate the images with analytical measurements. The results showed that the surface of the Fat globule was completely roughened after thermosonication. Ultrasound waves were responsible for disintegrating the milk Fat globule membrane (MFGM) by releasing the triacylglycerols. Furthermore, the overall structure of milk after sonication showed smaller Fat Globules (smaller than 1 microm) and a granular surface. This was due to the interaction between the disrupted MFGM and some casein micelles. Minor changes in the aspect of the Globules between thermal and raw milks were detected. Color measurements showed higher L* values for sonicated samples. Sonicated milk was whiter (92.37 +/- 0.20) and generally showed a better degree of luminosity and homogenization compared to thermal treated milk (88.25 +/- 0.67) and raw milk (87.82 +/- 0.18). Fat content analysis yielded a higher value after sonication (4.24%) compared to untreated raw milk (4.04%) because Fat extraction is more efficient after sonication. The advantages of thermosonicated milk are that it can be pasteurized and homogenized in just 1 step, it can be produced with important cost savings, and it has better characteristics, making thermosonication a potential processing method for milk and most other dairy products.