Effect of Particle Size and Interface Composition on the Lipid Digestion of Droplets Covered with Membrane Phospholipids

Preparation of infant formula simulating the fat composition and structure of human milk based on MFGM and exogenous phospholipid to modulate lipid digestion

In this study, raw cow's milk was used as raw material to investigate the impact of the order of egg yolk phospholipids (EYPL) addition in the actual production process on the structural integrity of milk fat globule membrane (MFGM) MFGM in infant formula (IF), and then to explore the impact of the addition of exogenous MFGM material concentration on the simulation of the physicochemical properties, microstructure, and lipid digestion in the IF emulsion and powder, and the determination of the base formulation of the IF. A portion of EYPL was added to raw cow's milk prior to homogenization (SIF1) and 2 % (w/w) EYPL was added directly to raw cow's milk along with other milk base ingredients (SIF2). The effects of human milk (HM) and three different infant formulas (SIF1, CIF1: no MFGM; CIF2: added MFGM) on their in vitro infant gastrointestinal digestion were also analyzed and compared. The results of the study show that the highest encapsulation rate (85.21 ± 1.03 %) and physical stability of the emulsions were achieved when a portion of EYPL was added to raw cow's milk first in the order of SIF preparation (SIF1) and at a concentration of MFGM addition of 2 % (w/w), which led to the identification of SIF1 as the order of simulated infant formula (SIF) preparation for the subsequent in vitro digestion experiments. After gastrointestinal digestion, only SIF had the closest free fatty acid composition to breast milk. Free fatty acid release was ranked in the order of HM > SIF > CIF2 ≥ CIF1. Overall, the addition of EYPL to SIF reduced the damage to the integrity of the milk fat globules caused by CIF while manufacturing and resulted in the highest similarity of fat digestion to HM.

Improving fat globule structure to narrow metabolite gap between human milk and infant formulae

We hypothesized that improving the fat globule structure of infant formulae based on the milk fat globule membrane (MFGM) would regulate metabolites and metabolic pathways, making it more similar to the metabolic properties of human milk. Therefore, we prepared infant formulae with different fat globule structures, including two model infant formulae (F1: fat globules surrounded by MFGM; F2: fat globules surrounded by protein) and one commercial infant formulae containing MFGM, and compared their metabolic differences with those of human milk. The number of differential metabolites between each sample and human milk reached 60 (F1), 132 (F2) and 126 (IF1). Glycerophosphocholines were screened as potential biomarkers to distinguish infant formulae from human milk. Compared with F2 and IF1, the enrichment of amino acid metabolism and lipid metabolism pathways was not significant between F1 and human milk. These results emphasized that F1 had the highest similarity to human milk in metabolic properties.

The Refractive Index of Human Milk Serum: Natural Variations and Dependency on Macronutrient Concentrations

The refractive index (RI) of human milk serum (also known as whey, milk soluble fraction or milk plasma) depends on the individual molecular species dissolved in the serum and their concentrations. Although the human milk serum RI is known to influence milk analysis methods based on light scattering, the RI dependency on human milk serum composition is currently unknown. Therefore, we systematically evaluate how the RI depends on natural variations in macronutrient concentrations in the soluble fraction. We measure RI variations in serum simulating samples with controlled macronutrient concentrations, as well as skimmed and whole fore-, bulk, and hindmilk from 19 donors. For both types of samples, we relate the measured RI to the macronutrient composition. From the serum simulating samples, we observe that the RI depends more on variations in whey protein, than carbohydrate concentrations, while minerals have negligible influence. For all donated samples, the average RI was 1.3470 (range 1.3466-1.3474). Per donor, no significant differences were observed in RI between fore-, bulk, and hindmilk. We conclude that protein and solids-not-fat (i.e., the total contribution of carbohydrates, proteins and minerals present in milk) concentrations are most predictive for human milk serum RI.

Phase inversion regulable bigels co-stabilized by Chlorella pyrenoidosa protein and beeswax: In-vitro digestion and food 3D printing

Algal proteins are an emerging source of functional foods. Herein, Chlorella pyrenoidosa protein (CPP)/xanthan gum-based hydrogels (HG) and beeswax-gelled oleogels (OG) are adopted to fabricate bigels. The phase inversion of bigels can be regulated by the ratio of OG and HG: As the OG increased, bigels turn from OG-in-HG (OG/HG) to a semicontinuous state and then HG-in-OG (HG/OG). In OG/HG bigels (OG ≤ 50 %), hydrophilic CPP acts as the emulsifier at the interface of OG and HG, while beeswax emulsifies the system in HG/OG bigels (OG = 80 %). A semicontinuous bigel appears during the transition between HG/OG and OG/HG. The increase of OG can enhance the viscoelasticity, hardness, adhesiveness, chewiness, and thermal stability. OG/HG bigels exhibit stronger thixotropic recovery and oil-holding capacity than HG/OG bigels. In the in-vitro digestion and food 3D printing, the high specific surface area and the highest thixotropic recovery caused by the emulsion structure of the OG/HG bigel (OG = 50 %) are conducive to the release of free fatty acids and molding of 3D-printed objects, respectively. This study provides a new approach to structure the gelled water-oil system with CPP and helps to develop edible algal proteins-based multiphase systems in food engineering or pharmacy.

Human milk fat substitutes rich in 1,3-dioleoyl-2-palmitoylglycerol and 1-oleoyl-2-palmitoyl-3-linoleoylglycerol simultaneously: Preparation strategy and simulated infant in vitro digestion

In this study, fractionated palm stearin, oleic acid, and linoleic acid were selected as the base materials to prepare human milk fat substitutes (HMFS) rich in OPO and OPL by enzymatic acidolysis combined with physical blending. Under optimum conditions, contents of OPO, OPL, and sn-2 palmitic acid in the OPO and OPL-rich triacylglycerols (TAGs) were higher than that in commercial OPO-rich TAGs, with values of 37.25%, 28.12%, and 79.44%, respectively. Physical blending the OPO and OPL-rich TAGs (47%), bovine milk fat (18%), sunflower oil (13%), coconut oil (13%), corn oil (8%), and palm oil (1%) can obtain HMFS with a fat composition that like HMF. The fatty acid, sn-2 saturated fatty acid, and TAG contents of HMFS were within the lower and upper limit of HMF. The lipolysis degree of infant formula (IF) with HMFS as fat source is 9.0% higher than that of commercial plant oil-based infant formula (PIF), and 3.4% lower than that of human milk. IF with HMFS as fat source released less saturated free fatty acids and more saturated monoacylglycerols during digestion than that of PIF, which would help improve the IF fat utilization by infants.

Simulated in vitro infant digestion and lipidomic analysis to explore how the milk fat globule membrane modulates fat digestion

We hypothesized that the addition of milk fat globule membranes (MFGMs) to infant formula would improve its lipolysis, making it more similar to human milk (HM) and superior to commercial infant formula (CIF) in fat digestion. Therefore, we prepared two model infant formulas (MIFs) by adding MFGMs to dairy ingredients in different ways and compared their fat digestion behavior with those of HM and CIF. MFGMs were added alone (MIF1) and with other milk-based materials (MIF2) before homogenization. The addition of MFGMs reduced the flocculation of lipids and proteins in the gastric phase and promoted lipolysis in the intestine phase. The amount of free fatty acids released followed the order of HM > MIF1 > CIF ≥ MIF2. After digestion, the number of different glyceride species between each sample and HM reached 64 (MIF1), 73 (MIF2), 67 (CIF1), and 72 (CIF2). In conclusion, the fat digestion of MIF1 had the highest similarity with HM.

Structural characteristics and in vitro starch digestibility of oil-modified cooked rice with varied addition manipulations

Lipid has crucial applications in improving the quality of starchy products during heat processing. Herein, the influence of lipid modification and thermal treatment on the physicochemical properties and starch digestibility of cooked rice prepared with varied addition manipulations was investigated. Rice bran oil (RO) and medium chain triglyceride oil (MO) manipulations were performed either before (BC) or after cooking (AC). GC-MS was applied to determine the fatty acid profiles. Nutritional quality was analyzed by quantifying total phenolics, atherogenic, and thrombogenic indices. All complexes exhibited higher surface firmness, a soft core, and less adhesive. FTIR spectrum demonstrated that the guest component affected some of the dense structural attributes of V-amylose. The kinetic constant was in the range between 0.47 and 0.86 min-1 wherein before mode presented a higher value. The lowest glucose release was observed in the RO_BC sample, whereas the highest complexing index was observed in the RO_AC sample, indicating that the dense molecular configuration of complexes that could resist enzymatic digestion was more critical than the quantity of complex formation. Despite the damage caused by mass and heat transfer, physical barrier, intact granule forms, and strengthened dense structure were the central contributors affecting the digestion characteristics of lipid-starch complexes.

Ultrasound modification on milk fat globule membrane and soy lecithin to improve the physicochemical properties, microstructure and stability of mimicking human milk fat emulsions

Starting from the consideration of the structure of human milk fat globule (MFG), this study aimed to investigate the effects of ultrasonic treatment on milk fat globule membrane (MFGM) and soy lecithin (SL) complexes and their role in mimicking human MFG emulsions. Ultrasonic power significantly affected the structure of the MFGM-SL complex, further promoting the unfolding of the molecular structure of the protein, and then increased solubility and surface hydrophobicity. Furthermore, the microstructure of mimicking MFG emulsions without sonication was unevenly distributed, and the average droplet diameter was large. After ultrasonic treatment, the droplets of the emulsion were more uniformly dispersed, the particle size was smaller, and the emulsification properties and stability were improved to varying degrees. Especially when the ultrasonic power was 300 W, the mimicking MFG emulsion had the highest encapsulation rate and emulsion activity index and emulsion stability index were increased by 60.88 % and 117.74 %, respectively. From the microstructure, it was observed that the spherical droplets of the mimicking MFG emulsion after appropriate ultrasonic treatment remain well separated without obvious flocculation. This study can provide a reference for the screening of milk fat globules mimicking membrane materials and the further utilization and development of ultrasound in infant formula.

Influence of pasteurization and spray drying on the fat digestion behavior of human milk fat analog emulsion: a simulated in vitro infant digestion study

BACKGROUND

Human milk fat analog emulsion (HMFAE) is an emulsion that mimics the composition and structure of human milk (HM) fat globules. The application of HMFAE in infant formula requires a series of milk powder processing steps, such as pasteurization and spray drying. However, the effect of milk powder processing on fat digestion of HMFAE is still unclear. In this study, the influence of pasteurization and spray drying on the lipolysis behavior of HMFAE was studied and compared with HM using a simulated infant in vitro digestion model.

RESULTS

Pasteurization and spray drying increased the flocculation and aggregation of lipid droplets in HMFAE during digestion. Spray drying destroyed the lipid droplet structure of HMFAE, and partial milk fat globule membrane-covered lipid droplets turned into protein-covered lipid droplets, which aggravated lipid-protein aggregation during gastric digestion and hindered fat digestion in the small intestine. The final lipolysis degree was in the order HM (64.55%) > HMFAE (63.41%) > pasteurized HMFAE (61.75%) > spray-dried HMFAE (60.57%). After complete gastrointestinal digestion, there were no significant differences in free fatty acid and sn-2 monoacylglycerol profile among the HMFAE, pasteurized HMFAE, and spray-dried HMFAE.

CONCLUSION

Milk powder processing can reduce lipolysis by altering the lipid droplet structure of HMFAE and the degree of lipid droplet aggregation during digestion. © 2024 Society of Chemical Industry.

Structure, Biological Functions, Separation, Properties, and Potential Applications of Milk Fat Globule Membrane (MFGM): A Review

BACKGROUND

The milk fat globule membrane (MFGM) is a thin film that exists within the milk emulsion, suspended on the surface of milk fat globules, and comprises a diverse array of bioactive components. Recent advancements in MFGM research have sparked a growing interest in its biological characteristics and health-related functions. Thorough exploration and utilization of MFGM as a significant bioactive constituent in milk emulsion can profoundly impact human health in a positive manner. Scope and approach: This review comprehensively examines the current progress in understanding the structure, composition, physicochemical properties, methods of separation and purification, and biological activity of MFGM. Additionally, it underscores the vast potential of MFGM in the development of additives and drug delivery systems, with a particular focus on harnessing the surface activity and stability of proteins and phospholipids present on the MFGM for the production of natural emulsifiers and drug encapsulation materials.

KEY FINDINGS AND CONCLUSIONS

MFGM harbors numerous active substances that possess diverse physiological functions, including the promotion of digestion, maintenance of the intestinal mucosal barrier, and facilitation of nerve development. Typically employed as a dietary supplement in infant formula, MFGM's exceptional surface activity has propelled its advancement toward becoming a natural emulsifier or encapsulation material. This surface activity is primarily derived from the amphiphilicity of polar lipids and the stability exhibited by highly glycosylated proteins.

Early-Life Exposure to Dietary Large Phospholipid-Coated Lipid Droplets Improves Markers of Metabolic and Immune Function in Adipose Tissue Later in Life in a Mouse Model

SCOPE

Human milk (HM) is considered optimal nutrition for infants, beneficially programming adult health outcomes including reduced obesity risk. Early life exposure to infant formula with lipid droplets closely resembling the structural properties of HM lipid globules (Nuturis) attenuated white adipose tissue (WAT) accumulation in mice upon adult western-style diet (WSD) feeding. Here, the study aims to elucidate underlying mechanisms.

METHODS AND RESULTS

Mice are raised on control or Nuturis diets between postnatal days 16-42 followed by either standard diet or WSD for 16 weeks. While the adult body composition of mice on a standard diet is not significantly affected, Nuturis reduced adiposity in mice on WSD. Morphologically, mean adipocyte size is reduced in Nuturis-raised mice, independent of adult diet exposure, and WAT macrophage content is reduced, albeit not significantly. Transcriptomics of epididymal WAT indicate potential beneficial effects on energy metabolism and macrophage function by Nuturis.

CONCLUSION

Reduced adult adiposity by early life exposure to Nuturis appears to be associated with smaller adipocytes and alterations in WAT immune and energy metabolism. These results suggest that early modulation of WAT structure and/or function may contribute to the protective programming effects of the early-life Nuturis diet on later-life adiposity.

Novel trends and challenges in fat modification of next-generation infant formula: Considering the structure of milk fat globules to improve lipid digestion and metabolism of infants

Differences in the composition and structure of lipid droplets in infant formula (IF) and human milk (HM) can affect the fat digestion of infants, leading to high risk of metabolic diseases during later stages of growth. Recently, interest in simulating HM fat (HMF) has gradually increased due to its beneficial functions for infants. Much research focuses on the simulation of fatty acids and triacylglycerols. Enzymatic combined with new technologies such as carbodiimide coupling immobilization enzymes, solvent-free synthesis, and microbial fermentation can improve the yield of simulated HMF. Furthermore, fat modification in next-generation IF requires attention to the impact on the structure and function of milk fat globules (MFG). This review also summarizes the latest reports on MFG structure simulation, mainly related to the addition method and sequence of membrane components, and other milk processing steps. Although some of the simulated HMF technologies and products have been applied to currently commercially available IF, the cost is still high. Furthermore, understanding the fat decomposition of simulated HMF during digestion and assessing its nutritional effects on infants later in life is also a huge challenge. New process development and more clinical studies are needed to construct and evaluate simulated HMF in the future.

Research progress on chitin/chitosan-based emulsion delivery systems and their application in lipid digestion regulation

Excessive lipid intake is linked to an elevated risk of health problems. However, reducing lipid contents may influence food structure and flavor. Some alternatives are needed to control the lipid absorption. Emulsions are common carriers for lipids, which can control the hydrolysis and absorption of lipids. Chitin (Ch) and chitosan (CS) are natural polysaccharides with good biodegradability, biocompatibility, and unique cationic properties. They have been reported to be able to delay lipolysis, which can be regarded as one of the most promising agents that regulates lipid digestion (LiD). The application of Ch/CS and their derivatives in emulsions are summarized in this review with a focus on their performances and mechanisms for LiD regulation, aiming to provide theoretical guidance for the development of novel Ch/CS emulsions, and the regulation of LiD. A reasonable design of emulsion interface can provide its resistance to the external environment and then control LiD. The properties of emulsion interface are the key factors affecting LiD. Therefore, systematic study on the relationship between Ch/CS-based emulsion structure and LiD can not only instruct the reasonable design of emulsion interface to accurately regulate LiD, but also provide scientific guidelines for applying Ch/CS in functional food, medicine and other fields.

Infant formula containing large, milk phospholipid-coated lipid droplets and dairy lipids affects cognitive performance at school age

Background

Breastfeeding has been positively associated with infant and child neurocognitive development and function. Contributing to this effect may be differences between human milk and infant formula in the milk lipid composition and milk fat globule structure.

Objective

To evaluate the effects of an infant formula mimicking human milk lipid composition and milk fat globule structure on childhood cognitive performance.

Methods

In a randomized, controlled trial, healthy term infants received until 4 months of age either a Standard infant formula (n = 108) or a Concept infant formula (n = 115) with large, milk phospholipid coated lipid droplets and containing dairy lipids. A breastfed reference group (n = 88) was included. Erythrocyte fatty acid composition was determined at 3 months of age. Neurocognitive function was assessed as exploratory follow-up outcome at 3, 4, and 5 years of age using the Flanker test, Dimensional Change Card Sort (DCCS) test and Picture Sequence Memory test from the National Institutes of Health Toolbox Cognition Battery. Mann-Whitney U test and Fisher exact test were used to compare groups.

Results

Erythrocyte omega-6 to -3 long-chain polyunsaturated fatty acid ratio appeared to be lower in the Concept compared to the Standard group (P = 0.025). At age 5, only the Concept group was comparable to the Breastfed group in the highest reached levels on the Flanker test, and the DCCS computed score was higher in the Concept compared to the Standard group (P = 0.021).

Conclusion

These outcomes suggest that exposure to an infant formula mimicking human milk lipid composition and milk fat globule structure positively affects child neurocognitive development. Underlying mechanisms may include a different omega-3 fatty acid status during the first months of life.

Clinical trial registration

https://onderzoekmetmensen.nl/en/trial/28614, identifier NTR3683 and NTR5538.

Comparison of phospholipid composition and microstructure of milk fat globules contained in human milk and infant formulae

Phospholipids play key roles in infant nutrition and cognitive development. It is hypothesized that infant formula (IF) has lower phospholipid species, content and milk fat globule (MFG) structural integrity than human milk (HM). Herein, we performed qualitative and quantitative analyses of phospholipids in six classes of IF and HM using ultra-performance liquid chromatography with mass spectrometry. The contents of phosphatidylethanolamine (15.81 ± 7.20 mg/L) and sphingomyelin (35.84 ± 15.56 mg/L) in IF were significantly lower than those in HM (30.74 ± 17.38 mg/L, 45.53 ± 16.04 mg/L, respectively). Among the six IF classes, cow's milk-based IF had the highest number of phospholipid species, and IF containing milk fat globular membrane had the highest phospholipid content. The size, zeta potential, and amount of MFGs in IF were significantly lower than those in HM. These results may prove useful for designing better IF that mimic HM.

Interfacial compositions of fat globules modulate structural characteristics and lipolysis of its model emulsions during in-vitro digestion

BACKGROUND

This study investigated whether milk fat globule membrane as an emulsifier could make fat easier for infants to digest. An emulsion was formed using the membrane material, where anhydrous milk fat was used as the core material, milk fat globule membrane polar lipid (MPL) as the emulsifier, and soybean phospholipid (PL) and milk protein concentrate (MPC) incorporated as control emulsifiers. Structural characterization, glyceride composition, and fatty acid release from emulsions by in vitro digestion were investigated.

RESULTS

The average particle size at the end of intestinal digestion was in the order MPL < PL < MPC, with diameters of 3.41 ± 0.51 μm, 3.53 ± 0.47 μm, and 10.46 ± 2.33 μm respectively. Meanwhile, laser scanning confocal microscopy results also illustrated that MPL could reduce the degree of aggregation during digestion. The lipolysis degree of MPL emulsion was higher than that of PL and MPC emulsions. MPL not only released higher levels of long-chain fatty acids, such as C18:1, C18:2, C18:3, which are of great significance for infant growth and development, but also released increased levels of C20:4 (arachidonic acid) and C22:6 (docosahexaenoic acid) than PL and MPC emulsions did.

CONCLUSION

Fat droplets enveloped by milk fat globule MPLs were easier to digest and are therefore more suitable for infant formula. © 2023 Society of Chemical Industry.

Fabrication and Characterization of Novel Food-Grade Bigels Based on Interfacial and Bulk Stabilization

Novel food-grade bigels were fabricated using zein nanoparticles for interfacial stabilization and non-surfactant gelators (beeswax and tapioca) for bulk stabilization. The present study demonstrated the importance of interfacial stability for biphasic gels and sheds light on the roles of the gelation mechanism and the oil/water ratio of a bigel on its microstructure, physical properties, and digestion behaviors. The results indicated that it is not an easy task to realize homogenization and subsequent gelation in beeswax-tapioca biphasic systems, as no amphiphilic components existed. However, applying the binding of zein nanoparticles at the oil-water interface allowed us to produce a homogeneous and stable bigel (oil fraction reach 40%), which exhibited enhanced structural and functional properties. Oleogel structures play a crucial role in determining the deformation response of bigel systems. As the oil content increased, the mechanical strength and elastic properties of bigels were enhanced. In the meantime, clear bigel-type transitions were observed. In addition, the fabricated bigels were shown to be beneficial for delayed digestion, and the lowest degree of lipolysis could be found in bigel with 50% oleogel.

Effect of oligosaccharides as lyoprotectants on the stability of curcumin-loaded nanoliposomes during lyophilization

Nanoliposome is a promising delivery system, whereas its commercial application is limited by the structural instability, cargo leakage and particles aggregation during the processing such as freeze-drying. In this study, the effect of four oligosaccharides, fructo-oligosaccharides, lactose, inulin and sucrose (control), on the physicochemical properties, structural stability, and in vitro semi-dynamic digestion behavior of curcumin-loaded nanoliposomes were investigated before and after lyophilization. The results showed that the addition of the oligosaccharides inhibited the changes in particle size and reduced curcumin leakage from lyophilized nanoliposomes. Oligosaccharides significantly improved the physical stability of lyophilized nanoliposomes and delayed curcumin release during in vitro digestion. In addition, oligosaccharides could decrease the hydrophobicity of liposomal membrane and the tightness of phospholipid molecule arrangement, with the increase in micropolarity and fluidity of the bilayer membranes. These results suggested that fructo-oligosaccharides, lactose and inulin could be effective lyoprotectants for lyophilized nanoliposomes.

Interfacial composition in infant formulas powder modulate lipid digestion in simulated in-vitro infant gastrointestinal digestion

The interface structure and composition of fat globules are very important for the digestion and metabolism of fat and growth in infants. Interface composition of fat globules in infant formula (IF) supplemented with milk fat globule membranes (MFGM) and lecithin in different ways were analyzed and their effects on fat digestion properties were evaluated. The results showed that the distribution of phospholipids at the interface and structural of Concept IF1 and Concept IF2 that were more similar to those of human milk (HM) than that of conventionally processed IF3. Concept IF2 and IF3 supplemented with lecithin had larger initial particle size and more sphingomyelin (SM) (23.12 ± 0.26 %, 26.94 ± 0.34 %) than Concept IF1, and Concept IF2 had the smallest proportion of casein in the interfacial. Due to its interface composition, Concept IF2 had the highest degree of lipolysis (85.07 ± 0.76 %), the phospholipid ring structure can always be observed during gastric digestion, and a final fatty acid composition released that was more similar to HM. Concept IF1 and IF3 were different from HM and Concept IF2 in terms of structure and lipolysis rate, although superior to commercial IF4. These indicate that changes in the interfacial composition and structure of fat globules improve the digestive properties of fats in IF. Overall, the results reported herein are useful in designing new milk formulas that better simulate HM.

The influence of MPL addition on structure, interfacial compositions and physicochemical properties on infant formula fat globules

The lack of milk fat globule membrane phospholipids (MPL) at the interface of infant formula fat globules has an impact on the stability of fat globules, compared to human milk. Therefore, infant formula powders with different MPL contents (0%, 10%, 20%, 40%, 80%, w/w of MPL/whey protein mixture) were prepared, and the effect of interfacial compositions on the stability of globules was investigated. With increasing MPL amount, the particle size distribution had two peaks and returned to a uniform state when 80% MPL was added. At this composition, the MPL at the oil-water interface formed a continuous thin layer. Moreover, the addition of MPL improved the electronegativity and the emulsion stability. In terms of the rheological properties, increasing the concentration of MPL improved the elastic properties of the emulsion and the physical stability of the fat globules, while reducing the aggregation and agglomeration between fat globules. However, the potential for oxidation increased. Based on these results, the interfacial properties and stability on infant formula fat globules was significantly influenced by the level of MPL, which should be considered in the design of infant milk powders.

Interaction between whey protein and soy lecithin and its influence on physicochemical properties and in vitro digestibility of emulsion: A consideration for mimicking milk fat globule

In this study, from the perspective of simulating the milk fat globule (MFG) emulsion, the interaction between soybean lecithin (SL) and the main protein in milk, whey protein (WP), and its effect on physical characteristics and lipid digestion were investigated through multiple spectroscopic techniques and in vitro digestion. The mechanism of SL and WP was static quenching, indicating that a complex formed between WP and SL through hydrophobic interaction and hydrogen bonding. The addition of SL changed the secondary structure of WP. When the ratio of SL to WP was 1:3, the obtained SL-WP emulsion that simulated milk fat globule exhibited the smallest particle size distribution and the highest absolute value of zeta potential. In addition, the emulsion exhibited high encapsulation efficiency (91.67 ± 1.24 %) and good stability. Compared with commercially available infant formula (IF), the final free fatty acid release of prepared SL-WP emulsion was close to that of human milk (HM). The addition of lecithin increased the digestibility of fat and the release of free fatty acids, and the digestive characteristic and particle size change also were closer to that of HM from results of kinetics of free fatty acid release and microstructure analysis.

Milk polar lipids composition and functionality: a systematic review

Polar lipids including glycerophospholipids and sphingophospholipids are important nutrients and milk is a major source, particularly for infants. This systematic review describes the human and bovine milk polar lipid composition, structural organization, sources for formulation, and physiological functionality. A total of 2840 records were retrieved through Scopus, 378 were included. Bovine milk is a good source of polar lipids, where yield and composition are highly dependent on the choice of dairy streams and processing. In milk, polar lipids are organized in the milk fat globule membrane as a tri-layer encapsulating triglyceride. The overall polar lipid concentration in human milk is dependent on many factors including lactational stage and maternal diet. Here, reasonable ranges were determined where possible. Similar for bovine milk, where differences in milk lipid concentration proved the largest factor determining variation. The role of milk polar lipids in human health has been demonstrated in several areas and critical review indicated that brain, immune and effects on lipid metabolism are best substantiated areas. Moreover, insights related to the milk fat globule membrane structure-function relation as well as superior activity of milk derived polar lipid compared to plant-derived sources are emerging areas of interest regarding future research and food innovations.

Roles of Milk Fat Globule Membrane on Fat Digestion and Infant Nutrition

Milk fats are present as globules emulsified in the aqueous phase of milk and stabilized by a delicate membrane architecture called milk fat globule membrane (MFGM). The unique structure and composition of the MFGM play an important role in fat digestion and the metabolic programming of neonates. The objective of this review is to compare the structure, composition, and physicochemical characteristics of fat globules in human milk, bovine milk, and infant formula. It provides an overview of the fat digestion process and enzymes in healthy infants, and describes the possible roles of the MFGM in association with factors affecting fat digestion. Lastly, the health benefits of the MFGM on infant nutrition and future perspectives are discussed with a focus on brain development, metabolic response, and gut health.

Influence of milk fat globule membrane and milk protein concentrate treated by ultrasound on the structural and emulsifying stability of mimicking human fat emulsions

The primary objective of the present study was to investigate the effectiveness of ultrasonic treatment time on the particle size, molecular weight, microstructure and solubility of milk fat globule membrane (rich in phospholipid, MPL) and milk protein concentrate (MPC). The mimicking human fat emulsions were prepared using modified proteins and compound vegetable oil and the structural, emulsifying properties and encapsulation efficiency of emulsions were evaluated. After ultrasonic treatment, the cavitation caused particle size decreased and structure change of both MPL and MPC, resulting in the enhancement of protein solubility. While, there was no significant change in molecular weight. Modified proteins by ultrasonic may cause a reduction in particle size and an improvement in emulsifying stability and encapsulation efficiency of emulsions. The optimal ultrasonic time to improve functional properties of MPL emulsion and MPC emulsion were 3 min and 6 min, respectively. The emulsifying stability of MPL emulsion was superior to MPC emulsion, which indicated that MPL is more suitable as membrane material to simulate human fat. Therefore, the obtained results can provide basis for quality control of infant formula.

Mongoliitalea daihaiensis sp. nov., isolated from Daihai Lake in Inner Mongolia

A novel Gram-negative strain, designated X100-76^T, was isolated from Daihai Lake in Inner Mongolia, Republic of China. The strain was non-motile, non-spore-forming, long-rod-shaped, oxidase positive and catalase positive. Colonies incubated at 33 °C on 2216 marine agar medium for 3 days were circular, smooth, transparent, convex with clear edges, orange-red in colour and approximately 1.0 mm in diameter. Growth occurred at pH 6.5-12 (optimum pH 7.5), in 0-5.0% (w/v) NaCl (optimum 1.5%, w/v) and at 4-40 °C (optimum 28-33 °C). Phylogenetic analysis based on 16S rRNA gene sequences showed that X100-76^T belongs to the genus Mongoliitalea and is most closely related to Mongoliitalea lutea MIM18^T with 98.3% sequence similarity. The total genome size of X100-76^T was 4,816,617 bp with a G + C content of 39.6%. The digital DNA-DNA hybridization and average nucleotide identity values between strain X100-76^T and M. lutea MIM18^T were both below the recommended cut-off values. Chemotaxonomic analysis revealed iso-C_15:0, Sum Feature 4 (anteiso-C_17:1 B and/or iso-C_17:1 I), C_15:1ω6c, Sum Feature 9 (C_16:0 10-methyl and/or iso-C_17:1ω9c), C_16:0 and iso-C_15:1 G as the major fatty acids, menaquinone MK-7 as the major isoprenoid quinone, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and phosphatidylinositol as the major cellular polar lipids. The results of polyphasic analysis demonstrated that X100-76^T represents a novel species within the genus Mongoliitalea, for which the name Mongoliitalea daihaiensis sp. nov. is proposed. The type strain is X100-76^T (= CGMCC 1.18762^T = KCTC 82458^T).

Comparative Analysis of Lipid Digestion Characteristics in Human, Bovine, and Caprine Milk Based on Simulated In Vitro Infant Gastrointestinal Digestion

Lipid digestion characteristics in human, bovine, and caprine milk were investigated using an infant in vitro digestion model. Our results suggested that particle size in bovine and caprine milk increased initially and then decreased over time, whereas the particle size in human milk continuously decreased. The lipolysis degree of human milk (86.8%) was higher than that in bovine (80.2%) and caprine (82.7%) milk (P < 0.05). Compared to human milk, bovine and caprine milk released higher unsaturated fatty acids and lower SFAs. In addition, 12 and 84 glyceride species were significantly different between bovine and human milk, during gastrointestinal digestion (P < 0.05). Another 13 and 92 glyceride species were found to be significantly different between caprine and human milk. A total of 30 and 31 lipids were screened as biomarkers to further clarify the differences related to lipid digestion properties of human, bovine, and caprine milk.

Dairy Processing Affects the Gut Digestion and Microecology by Changing the Structure and Composition of Milk Fat Globules

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.

Kinetic Modeling of In Vitro Small Intestinal Lipid Digestion as Affected by the Emulsion Interfacial Composition and Gastric Prelipolysis

This research evaluated the impact of the emulsion interfacial composition on in vitro small intestinal lipolysis kinetics with the inclusion of rabbit gastric lipase resulting in a gastric prelipolysis step. O/w emulsions contained 5% triolein (w/w) and 1% (w/w) of the following emulsifiers: sodium taurodeoxycholate, citrus pectin, soy protein isolate, soy lecithin, and tween 80. Emulsions were subjected to static in vitro digestion and diverse lipolysis species quantified via a HPLC-charged aerosol detector. Single-response modeling indicated that the kinetics of lipolysis in the small intestinal phase were impacted by the emulsion particle size at the beginning of this phase. Multiresponse modeling permitted the elucidation of the lipolysis mechanism under in vitro conditions. The final reaction scheme included enzymatic and chemical conversions. The modeling strategies used in this research allowed to gain more insights into the kinetics and mechanism of in vitro lipid digestion.