Current perspectives on the use of milk fat globule membrane in infant milk formula

Sources of milk fat globule membrane (MFGM) are desirable to include in infant milk formula (IMF) to mimic the composition and functionality of human milk MFGM. MFGM in its natural form consists of a trilayer structure containing lipids (e.g., cholesterol, phospholipids, gangliosides, ceramides), proteins (e.g., butyrophilin, xanthine oxidase, mucin-1, adipophilin) and glycans (e.g., sialic acid). Components of MFGM have been associated with various biological benefit areas including intestinal, neurocognitive, and immune health. There are many aspects to consider when supplementing IMF with MFGM ingredients, of which the major ones are highlighted and critiqued in this review from an industrial research perspective. Features include compositional unknowns, discussion on how best to incorporate MFGM to IMF, analytical method needs, biological function unknowns, and considerations on how best to communicate MFGM in different contexts. It is hoped that by identifying the key scientific gaps outstanding in this subject area, collective efforts can proceed to ensure the potential impact of MFGM on infant health is realized.

Camembert-Type Cheese with Sweet Buttermilk: The Determination of Quality Properties and Microstructure

Camembert is a type of surface-mold-ripened soft cheese traditionally produced from cow's milk. Buttermilk, a by-product of butter production with beneficial nutritional and technological properties, is increasingly being used in various applications, including cheesemaking. Therefore, this study aimed to use sweet buttermilk (BM) in combination with milk at concentrations of 10% (w/w) (BM10) and 20% (w/w) (BM20) for the production of Camembert-type cheese. A control cheese made entirely from milk was also produced. The cheese samples underwent a 28-day ripening process during which their composition, acidity, water activity, color, and sensory properties were examined at 1-week intervals. The microstructure of the matured Camembert-type cheese samples was analyzed using scanning electron microscopy (SEM), and their texture was evaluated. The production yield of BM20 cheese (18.03 ± 0.29 kg/100 kg) was lower (p < 0.05) than that of the control (19.92 ± 0.23 kg/100 kg), with BM10 showing the distinctly lowest yield (14.74 ± 0.35 kg/100 kg). The total solid and fat content of BM Camembert-type cheese samples was lower than the control. However, the total protein content in cheese BM20 at the end of the ripening period was the same as that of the control. The changes in acidity in all samples were typical for Camembert cheese, and water activity was high (above 0.92). The sensory properties of all samples were characteristic of the cheese type, while the color of BM cheese samples differed from the control. The microstructure of BM10 and BM20 cheese variants was similar, namely homogenous and less porous compared to the control. In terms of texture, the BM samples had significantly lower hardness, adhesiveness, and gumminess. This study indicates that sweet BM, particularly at a concentration of 20%, may be effectively used in the production of Camembert-type cheese.

An in vitro evaluation of the effect of antimicrobial treatment on bovine mammary microbiota

Antimicrobial-resistant bacteria have been an increasing problem in human medicine and animal husbandry since the introduction of antimicrobials on the market in the 1940s. Over the last decades, efforts to reduce antimicrobial usage in animal husbandry have been shown to limit the development of resistant bacteria. Despite this, antimicrobial-resistant bacteria are still commonly detected and isolated worldwide. In this study, we investigated the presence of antimicrobial-resistant bacteria in bovine milk samples using a multiple approach based on culturing and amplicon sequencing. We first enriched milk samples obtained aseptically from bovine udders in the presence of two antimicrobials commonly used to treat mastitis and then described the resistant microbiota by amplicon sequencing and isolate characterization. Our results show that several commensal species and mastitis pathogens harbor antimicrobial resistance and dominate the enriched microbiota in milk in presence of antimicrobial agents. The use of the two different antimicrobials selected for different bacterial taxa and affected the overall microbial composition. These results provide new information on how different antimicrobials can shape the microbiota which is able to survive and reestablish in the udder and point to the fact that antimicrobial resistance is widely spread also in commensal species.

Comprehensive review of milk fat globule membrane proteins across mammals and lactation periods in health and disease

Milk fat globule membrane (MFGM) is a three-layer membrane-like structure encasing natural milk fat globules (MFGs). MFGM holds promise as a nutritional supplement because of the numerous physiological functions of its constituent protein. This review summarizes and compares the differences in MFGM protein composition across various species, including bovines, goats, camels, mares, and donkeys, and different lactation periods, such as colostrum and mature milk, as assessed by techniques such as proteomics and mass spectrometry. We also discuss the health benefits of MFGM proteins throughout life. MFGM proteins promote intestinal development, neurodevelopment, and glucose and lipid metabolism by upregulating tight junction protein expression, brain function-related genes, and glucose and fatty acid biosynthesis processes. We focus on the mechanisms underlying these beneficial effects of MFGM proteins. MFGM proteins activate key substances in in signaling pathways, such as the phosphatidylinositol 3-kinase/protein kinase B, mitogen-activated protein kinase, and myosin light chain kinase signaling pathways. Overall, the consumption of MFGM proteins plays an essential role in conferring health benefits, some of which are important throughout the mammalian life cycle.

Partition of milk phospholipids during ice cream manufacturing

The distribution of phospholipids (PL) within the fat and serum phase of ice cream manufacturing was evaluated through partition coefficients (KPL) after mixing, pasteurization, freezing, and hardening. Ice creams containing about 40.41 ± 3.45 (± standard deviation; control formulation) and 112.29 ± 9.06 (enriched PL formulation) mg of PL per g of fat were formulated with nonfat dry milk and β-serum, respectively. Overall, the KPL were lower than 1, indicating that the PL were predominantly found in the fat phase, and only a small amount was left in the serum and sediment. Confocal micrographs visually confirmed this generalization. The addition of PL significantly increased the viscosity of the mixes between 4- and 9-fold, depending on the shear rate. Additionally, mixes containing high PL exhibited higher yield stress than those formulated with low PL (0.15 ± 0.09 and 0.016 ± 0.08 Pa, respectively). Ice creams with high PL delayed the onset of meltdown and exhibited a slower rate of a meltdown than low-PL ice creams (18.53 ± 0.57 and 14.83 ± 0.85 min, and 1.01 ± 0.05 and 0.71 ± 0.04% min-1, respectively). This study provides useful guidelines for manufacturing ice cream enriched in milk PL. Additionally, the use of β-serum, a byproduct stream, as a source of PL is illustrated. The development will require studying the sensorial description of the product as well as consumer acceptance.

Surface proteins of Shiga toxin-producing Escherichia coli mediate association with milk fat globules in raw milk

Introduction

By adhering to host cells and colonizing tissues, bacterial pathogens can successfully establish infection. Adhesion is considered the first step of the infection process and bacterial adhesion to anti-adhesive compounds is now seen as a promising strategy to prevent infectious diseases. Among the natural sources of anti-adhesive molecules, the membrane of milk fat globules (MFGs) is of interest because of its compositional diversity of proteins and glycoconjugates. However, few studies have focused on the bacterial molecules involved in MFG- mediated inhibition of bacterial adhesion to enterocytes.

Methods

We used three pathogenic Shiga toxin-producing Escherichia coli (STEC) strains (O26:H11 str. 21765, O157:H7 str. EDL933, and O103:H3 str. PMK5) as models to evaluate whether STEC surface proteins are involved in the affinity of STEC for MFG membrane proteins (MFGMPs). The affinity of STEC for MFGMPs was assessed both indirectly by a natural raw milk creaming test and directly by an adhesion test. Mass spectrometry was used to identify enriched STEC proteins within the protein fraction of MFGMs. Bacterial mutants were constructed and their affinity to MFGs were measured to confirm the role of the identified proteins.

Results

We found that free STEC surface proteins inhibit the concentration of the pathogen in the MFG-enriched cream in a strain-dependent manner. Moreover, the OmpA and FliC proteins were identified within the protein fraction of MFGMs. Our results suggest that FliC protein participates in STEC adhesion to MFGMPs but other STEC molecules may also participate.

Discussion

For the first time, this study highlighted, the involvement of STEC surface proteins in the affinity for MFGs. The mechanism of STEC-MFG association is still not fully understood but our results confirm the existence of receptor/ligand type interactions between the bacteria and MFGs. Further studies are needed to identify and specify the molecules involved in this interaction. These studies should consider the likely involvement of several factors, including adhesion molecules, and the diversity of each STEC strain.

Changes in Milk Fat Globules and Membrane Proteins Prepared from pH-Adjusted Bovine Raw Milk

Milk fat globules (MFGs) have tri-layer biological membrane structures, and their compositions are gaining more interest for their physiological benefits. In this study, the changes in MFGs and milk fat globule membrane (MFGM) proteins after cream separation from different pH bovine raw milk were investigated. Raw milk samples were adjusted to pH 5.30 and 6.30 using citric acid at 25 °C. The effect of pH and centrifugation on the structure of MFGs was evaluated by means of particle size, zeta potential and confocal laser scanning microscopy (CLSM). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze the proteins in the obtained fractions. It was found that both pH and centrifugation could affect the particle size of all samples. As the volume distribution (Dv; Dv (10), Dv(50)and Dv (90)) decreased, the corresponding specific surface area (SSA) increased, and span and uniformity values showed the same trend. The decrease in the zeta potential of MFG correlated with the Dv(50), which was further confirmed by CLSM observation. More butyrophilin (BTN) and periodic acid Schiff 6/7 (PAS 6/7) were lost in cream samples at pH 5.30. The findings could provide valuable knowledge for the application of MFGs ingredient in the food industry since their structures and compositions could affect their potential functional and physiological properties.

The nutritional functions of dietary sphingomyelin and its applications in food

Sphingolipids are common structural components of cell membranes and are crucial for cell functions in physiological and pathophysiological conditions. Sphingomyelin and its metabolites, such as sphingoid bases, ceramide, ceramide-1-phosphate, and sphingosine-1-phosphate, play signaling roles in the regulation of human health. The diverse structures of sphingolipids elicit various functions in cellular membranes and signal transduction, which may affect cell growth, differentiation, apoptosis, and maintain biological activities. As nutrients, dietary sphingomyelin and its metabolites have wide applications in the food and pharmaceutical industry. In this review, we summarized the distribution, classifications, structures, digestion, absorption and metabolic pathways of sphingolipids, and discussed the nutritional functioning of sphingomyelin in chronic metabolic diseases. The possible implications of dietary sphingomyelin in the modern food preparations including dairy products and infant formula, skin improvement, delivery system and oil organogels are also evaluated. The production of endogenous sphingomyelin is linked to pathological changes in obesity, diabetes, and atherosclerosis. However, dietary supplementations of sphingomyelin and its metabolites have been shown to maintain cholesterol homeostasis and lipid metabolism, and to prevent or treat these diseases. This seemly paradoxical phenomenon shows that dietary sphingomyelin and its metabolites are candidates for food additives and functional food development for the prevention and treatment of chronic metabolic diseases in humans.

Shiga Toxin-Producing Escherichia coli and Milk Fat Globules

Shiga toxin-producing Escherichia coli (STEC) are zoonotic Gram-negative bacteria. While raw milk cheese consumption is healthful, contamination with pathogens such as STEC can occur due to poor hygiene practices at the farm level. STEC infections cause mild to serious symptoms in humans. The raw milk cheese-making process concentrates certain milk macromolecules such as proteins and milk fat globules (MFGs), allowing the intrinsic beneficial and pathogenic microflora to continue to thrive. MFGs are surrounded by a biological membrane, the milk fat globule membrane (MFGM), which has a globally positive health effect, including inhibition of pathogen adhesion. In this review, we provide an update on the adhesion between STEC and raw MFGs and highlight the consequences of this interaction in terms of food safety, pathogen detection, and therapeutic development.

The Characteristics of Quark Cheese Made from Buttermilk during Refrigerated Storage

The dairy industry releases huge amounts of by-products. One of them is buttermilk, obtained during butter production. This by-product is characterized by high nutritional and technological value and is finding more and more applications in food production. This study aimed to produce and analyze the characteristics of quark cheese obtained entirely from buttermilk during 3-week refrigerated (4 ± 1 °C) storage. Four kinds of sour buttermilk were used: two from industrial butter production, and another two from butter production at laboratory scale. Laboratory buttermilk differs in the kind of starter culture used in the production. The evaluation of cheese quality properties included physicochemical analyses, texture measurement, and sensory assessment. The results showed that the kind of buttermilk used in production influences the acidity, total solids, textural characteristics, and fat content of the obtained quark cheeses. All obtained cheeses had very high sensory quality throughout the storage period. The study indicates that buttermilk may be successfully used as a substitution for milk in quark cheese production.

Milk fat globule membrane in infant nutrition: a dairy industry perspective

This review provides an overview of the composition, structure, and biological activities of milk fat globule membrane (MFGM) compounds with focus on the future application of this compound as a food ingredient. MFGM is a particular component of mammalian milks and is comprised of a tri-layer of polar lipids, glycolipids and proteins. In recent years, MFGM has been extensively studied for the purpose of enhancing the efficacy of infant nutrition formula. For example, infant formulas supplemented with bovine MFGM have shown promising results with regard to neurodevelopment and defense against infections. Components of MFGM have been shown to present several health benefits as the proteins of the membrane have shown antiviral activity and a reduction in the incidence of diarrhea. Moreover, the presence of sphingomyelin, a phospholipid, implies beneficial effects on human health such as enhanced neuronal development in infants and the protection of neonates from bacterial infections. The development of a lipid that is similar to human milk fat would represent a significant advance for the infant formula industry and would offer high technology formulas for those infants that depend on infant formula. The complexity of the structure of MFGM and its nutritional and technological properties is critically examined in this review with a focus on issues relevant to the dairy industry.

Improving Human Health with Milk Fat Globule Membrane, Lactic Acid Bacteria, and Bifidobacteria

The milk fat globule membrane (MFGM), the component that surrounds fat globules in milk, and its constituents have gained significant attention for their gut function, immune-boosting properties, and cognitive-development roles. The MFGM can directly interact with probiotic bacteria, such as bifidobacteria and lactic acid bacteria (LAB), through interactions with bacterial surface proteins. With these interactions in mind, increasing evidence supports a synergistic effect between MFGM and probiotics to benefit human health at all ages. This important synergy affects the survival and adhesion of probiotic bacteria through gastrointestinal transit, mucosal immunity, and neurocognitive behavior in developing infants. In this review, we highlight the current understanding of the co-supplementation of MFGM and probiotics with a specific emphasis on their interactions and colocalization in dairy foods, supporting in vivo and clinical evidence, and current and future potential applications.

Effects of pressure, shear, temperature, and their interactions on selected milk quality attributes

The effects of pressure, temperature, shear, and their interactions on selected quality attributes and stability of milk during ultra-shear technology (UST) were investigated. The UST experiments include pressure (400 MPa) treatment of the milk sample preconditioned at 2 different initial temperatures (25°C and 15°C) and subsequently depressurizing it via a shear valve at 2 flow rates (low: 0.15-0.36 g/s; high: 1.11-1.22 g/s). Raw milk, high-pressure processed (HPP; 400 MPa, ~40°C for 0 and 3 min) and thermal treated (72°C for 15 s) milk samples served as the controls. The effect of different process parameters on milk quality attributes were evaluated using particle size, zeta potential, viscosity, pH, creaming, lipase activity, and protein profile. The HPP treatment did not cause apparent particle size reduction but increased the sample viscosity up to 3.08 mPa·s compared with 2.68 mPa·s for raw milk. Moreover, it produced varied effects on creaming and lipase activity depending on hold time. Thermal treatment induced slight reduction in particle size and creaming as compared with raw milk. The UST treatment at 35°C reduced the effective diameter of sample particles from 3,511.76 nm (raw milk) to 291.45 nm. This treatment also showed minimum relative lipase activity (29.93%) and kept milk stable by preventing creaming. The differential effects of pressure, shear, temperature, and their interactions were evident, which would be useful information for equipment developers and food processors interested in developing improved food processes for dairy beverages.

Sources, Production, and Clinical Treatments of Milk Fat Globule Membrane for Infant Nutrition and Well-Being

Research on milk fat globule membrane (MFGM) is gaining traction. The interest is two-fold; on the one hand, it is a unique trilayer structure with specific secretory function. On the other hand, it is the basis for ingredients with the presence of phospho- and sphingolipids and glycoproteins, which are being used as food ingredients with valuable functionality, in particular, for use as a supplement in infant nutrition. This last application is at the center of this Review, which aims to contribute to understanding MFGM's function in the proper development of immunity, cognition, and intestinal trophism, in addition to other potential effects such as prevention of diseases including cardiovascular disease, impaired bone turnover and inflammation, skin conditions, and infections as well as age-associated cognitive decline and muscle loss. The phospholipid composition of MFGM from bovine milk is quite like human milk and, although there are some differences due to dairy processing, these do not result in a chemical change. The MFGM ingredients, as used to improve the formulation in different clinical studies, have indeed increased the presence of phospholipids, sphingolipids, glycolipids, and glycoproteins with the resulting benefits of different outcomes (especially immune and cognitive outcomes) with no reported adverse effects. Nevertheless, the precise mechanism(s) of action of MFGM remain to be elucidated and further basic investigation is warranted.

Milk polar lipids reduce lipid cardiovascular risk factors in overweight postmenopausal women: towards a gut sphingomyelin-cholesterol interplay

OBJECTIVE

To investigate whether milk polar lipids (PL) impact human intestinal lipid absorption, metabolism, microbiota and associated markers of cardiometabolic health.

DESIGN

A double-blind, randomised controlled 4-week study involving 58 postmenopausal women was used to assess the chronic effects of milk PL consumption (0, 3 or 5 g-PL/day) on lipid metabolism and gut microbiota. The acute effects of milk PL on intestinal absorption and metabolism of cholesterol were assessed in a randomised controlled crossover study using tracers in ileostomy patients.

RESULTS

Over 4 weeks, milk PL significantly reduced fasting and postprandial plasma concentrations of cholesterol and surrogate lipid markers of cardiovascular disease risk, including total/high-density lipoprotein-cholesterol and apolipoprotein (Apo)B/ApoA1 ratios. The highest PL dose preferentially induced a decreased number of intestine-derived chylomicron particles. Also, milk PL increased faecal loss of coprostanol, a gut-derived metabolite of cholesterol, but major bacterial populations and faecal short-chain fatty acids were not affected by milk PL, regardless of the dose. Acute ingestion of milk PL by ileostomy patients shows that milk PL decreased cholesterol absorption and increased cholesterol-ileal efflux, which can be explained by the observed co-excretion with milk sphingomyelin in the gut.

CONCLUSION

The present data demonstrate for the first time in humans that milk PL can improve the cardiometabolic health by decreasing several lipid cardiovascular markers, notably through a reduced intestinal cholesterol absorption involving specific interactions in the gut, without disturbing the major bacterial phyla of gut microbiota.

TRIAL REGISTRATION NUMBER

NCT02099032 and NCT02146339; Results.

Buttermilk ice cream-New method for buttermilk utilization

Buttermilk, the by‐product of butter production, due to good technological features and excellent nutritional and health‐promoting properties finds more and more applications in food industry. Considerable amount of polar lipids causes that buttermilk exhibits emulsifying and stabilizing effect and may be used to improve the product quality. The study aimed to design new kind of ice cream, in which all milk is substituted by buttermilk. Within the study, we compared physicochemical parameters, color, texture, and sensory properties of control milk ice cream (C), ice cream from sweet buttermilk (SB), and ice cream from cultured buttermilk (CB). Ice cream was tested on the production day, and some characteristics were tested also after 14 and 28 days of storage at −18 ± 1°C. The study showed that samples of ice cream from cultured buttermilk had the highest acidity and were the most resistant to melting. The samples did not differ in over‐run value. The use of buttermilk influenced the texture of ice cream and product from sweet buttermilk had the highest stickiness during the storage. The color analysis showed that the highest lightness parameter had ice cream from cultured buttermilk, while samples from sweet buttermilk had the most greenish‐yellow characteristics. All the obtained products had good sensory characteristics, only cultured buttermilk ice cream slightly deteriorated after 28 storage days. Good quality properties cause that buttermilk may be successfully used as substitution of milk in ice‐cream formula and may improve its quality by exhibiting of some emulsifying stabilizing effect.

Application of zinc and calcium acetate to precipitate milk fat globule membrane components from a dairy by-product

There has been a great deal of interest in developing isolated dairy lipid fractions that are rich in phospholipids (PL), due to their health benefits and functional properties. Dairy by-products that contain elevated levels of PL and milk fat globule membrane (MFGM) proteins can be an excellent source for these isolates. The β stream, a by-product of anhydrous milk fat production, is an excellent candidate because it contains a higher concentration of PL than many other dairy by-products. In this study, we investigated an economically feasible processing method to obtain these valuable components from the β stream. The use of zinc acetate and calcium acetate, along with mild heat treatment and pH adjustment, was effective in precipitating PL and proteins into a pellet fraction. With an additional extraction from the pellet using ethanol (90% at 70°C), a PL-enriched lipid fraction was obtained. The effective precipitation conditions were zinc acetate of 25 mM concentration at pH greater than 6.5 at 30°C, and calcium acetate of greater than 75 mM concentration at pH greater than 6.5 at 60°C. With ethanol extraction, PL recovery of 97.7 ± 1.7% from the zinc acetate precipitate and 94.9 ± 3.7% from calcium acetate precipitate were achieved.

The effect of dietary forage to concentrate ratio and forage type on milk fatty acid composition and milk fat globule size of lactating cows

We examined the effects of 2 grass silage-based diets differing in forage:concentrate (FC) ratio and those of a red clover silage-based diet on intake, milk production, ruminal fatty acid (FA) biohydrogenation, milk FA composition, and milk fat globule (MFG) size distribution. Ten multiparous Nordic Red cows received the following treatments: grass silage-based diets containing high (70:30, HG) or low (30:70, LG) FC ratio or a red clover silage-based diet with an FC ratio of 50:50 (RC) on a dry matter basis. Determinations of MFG were performed from fresh milk samples without addition of EDTA so the results of fat globules >1 µm in diameter are emphasized instead of the entire globule population. Lower FC ratio in grass silage-based diets increased milk production with no effect on daily fat yield, leading to 13% lower milk fat concentration. The effect of FC ratio on MFG size was moderate. It did not affect the volume-weighted diameter in grass silage-based diets, although LG lowered the volume-surface diameter of MFG in the size class >1 µm compared with HG. Compared with HG, feeding LG moderately decreased the biohydrogenation of 18:2n-6, leading to a higher level of polyunsaturated fatty acids in milk fat. Feeding RC lowered milk fat concentration and daily milk fat yield compared with grass silage-based diets. The volume-weighted diameter of MFG in the size class >1 µm was smaller in RC milk compared with grass silage-based diets. Feeding RC increased the flow of 18:3n-3 at the omasum by 2.4-fold and decreased the apparent ruminal 18:3n-3 biohydrogenation compared with grass silage-based diets despite similar intake of 18:3n-3. It also resulted in the lowest amount of saturated FA and the highest amounts of cis-9 18:1, 18:3n-3, and polyunsaturated FA in milk. In conclusion, LG decreased milk fat content and induced minor changes in MFG size distribution compared with HG, whereas RC lowered milk fat production, altered milk FA composition to nutritionally more beneficial direction, and led to smaller MFG compared with grass silage-based diets.

Agro-Food Byproducts as a New Source of Natural Food Additives

Nowadays, the agro-food industry generates high amounts of byproducts that may possess added value compounds with high functionality and/or bioactivity. Additionally, consumers' demand for healthier foodstuffs has increased over the last years, and thus the food industry has strived to answer this challenge. Byproducts are generally secondary products derived from primary agro-food production processes and represent an interesting and cheaper source of potentially functional ingredients, such as peptides, carotenoids, and phenolic compounds, thus promoting a circular economy concept. The existing body of work has shown that byproducts and their extracts may be successfully incorporated into foodstuffs, for instance, phenolic compounds from eggplant can be potentially used as a mulfitunctional food additive with antimicrobial, antioxidant, and food colorant properties. As such, the aim of this review is to provide insights into byproducts and their potential as new sources of foodstuffs additives.

Effect of bovine milk fat globule membranes as a complementary food on the serum metabolome and immune markers of 6-11-month-old Peruvian infants

This study builds on a previous study by this group in which 6–11-month-old Peruvian infants who were fed bovine milk fat globule membrane (MFGM) containing complementary food had significantly fewer episodes of infection-related bloody diarrhea relative to those consuming a control food (skim milk powder). Micronutrient deficiencies including zinc deficiency were prevalent in this study population. To understand the mechanism behind the health benefits of consuming MFGM, the serum metabolome and cytokine levels, as markers for systemic immune responses, were evaluated using ¹H nuclear magnetic resonance-based metabolomics and a multiplex system, respectively. Combined with data on micronutrient status and anthropometry, a comparative analysis was performed. Supplementation with MFGM tended to improve micronutrient status, energy metabolism, and growth reflected as increased levels of circulating amino acids and weight gain, particularly in female infants compared to controls. Decreased levels of the microbial choline metabolite trimethylamine-N-oxide in the MFGM-supplemented group (both male and female infants) suggest a functional perturbation in the intestinal microbiota. A cytokine shift toward a less T helper type 1 response was observed in those receiving the MFGM supplement, which was mainly attributed to decreases in interleukin-2 levels. Our findings suggest that consumption of MFGM with complementary food may reverse the metabolic abnormalities found in marginally nourished infants, thereby improving metabolic regulation, which may lead to enhanced immunity.

Bovine milk fat globule membrane (MFGM)-enriched complementary food has been recognized to be capable of reducing the episodes of bloody diarrhea in marginally nourished infants. However, the metabolic influence of MFGM remains unknown. Carolyn Slupsky from University of California-Davis and co-workers studied the impacts of bovine MFGM consumption on the levels of serum metabolome and immune markers. They found the supplements of MFGM improved the micronutrient status, energy metabolism, and growth, especially prominent for female infants. Moreover, MFGM complementary food lowered the level of the bacterial choline metabolite trimethylamine-N-oxide in the infants, indicating a functional perturbation to their intestinal microbiota. These findings suggest MFGM in complementary food can help to regulate the metabolic abnormalities of the infants with micronutrient deficiency, probably resulting in enhanced immunity.

Milk fat globule membrane glycoproteins: Valuable ingredients for lactic acid bacteria encapsulation?

The membrane (Milk Fat Globule Membrane - MFGM) surrounding the milk fat globule is becoming increasingly studied for its use in food applications due to proven nutritional and technological properties. This review focuses first on current researches which have been led on the MFGM structure and composition and also on laboratory and industrial purification and isolation methods developed in the last few years. The nutritional, health benefits and techno-functional properties of the MFGM are then discussed. Finally, new techno-functional opportunities of MFGM glycoproteins as a possible ingredient for Lactic Acid Bacteria (LAB) encapsulation are detailed. The ability of MFGM to form liposomes entrapping bioactive compounds has been already demonstrated. One drawback is that liposomes are too small to be used for bacteria encapsulation. For the first time, this review points out the numerous advantages to use MFGM glycoproteins as a protecting, encapsulating matrix for bacteria and especially for LAB.

Antirotaviral Activity of Bovine and Ovine Dairy Byproducts

Rotaviral gastroenteritis is associated with significant morbidity in developed countries and a high rate of infant mortality in developing countries. Diverse studies have demonstrated that a wide range of milk-derived fractions exhibit antirotaviral activity. The present study shows the antirotaviral activity of some bovine and ovine dairy byproducts, buttermilk, butter serum, and milk fat globule membrane (MFGM), and evaluates the effect of cream washing and heat treatment on that activity. Furthermore, the rotavirus-neutralizing activity was evaluated for some MFGM proteins, such as xanthine oxidase and lactophorin. Ovine and bovine buttermilk reached rotavirus-neutralizing values of 51.3 and 32.2%, at 1 mg/mL, respectively. The cream washing process led to a significant decrease in the antirotaviral activity of fractions. This activity was also influenced by heat treatment. Treatment at 75 °C for 20 s caused 24.6 and 36.1% decreases of activity in bovine and ovine buttermilk, respectively, and 85 °C for 10 min caused decreases of 80.9 and 79.0% in both fractions, respectively.

Organization of lipids in milks, infant milk formulas and various dairy products: role of technological processes and potential impacts

The microstructure of milk fat in processed dairy products is poorly known despite its importance in their functional, sensorial and nutritional properties. However, for the last 10 years, several research groups including our laboratory have significantly contributed to increasing knowledge on the organization of lipids in situ in dairy products. This paper provides an overview of recent advances on the organization of lipids in the milk fat globule membrane using microscopy techniques (mainly confocal microscopy and atomic force microscopy). Also, this overview brings structural information about the organization of lipids in situ in commercialized milks, infant milk formulas and various dairy products (cream, butter, buttermilk, butter serum and cheeses). The main mechanical treatment used in the dairy industry, homogenization, decreases the size of milk fat globules, changes the architecture (composition and organization) of the fat/water interface and affects the interactions between lipid droplets and the protein network (concept of inert vs active fillers). The potential impacts of the organization of lipids and of the alteration of the milk fat globule membrane are discussed, and technological strategies are proposed, in priority to design biomimetic lipid droplets in infant milk formulas.

Lactic acid bacteria in dairy food: surface characterization and interactions with food matrix components

This review gives an overview of the importance of interactions occurring in dairy matrices between Lactic Acid Bacteria and milk components. Dairy products are important sources of biological active compounds of particular relevance to human health. These compounds include immunoglobulins, whey proteins and peptides, polar lipids, and lactic acid bacteria including probiotics. A better understanding of interactions between bioactive components and their delivery matrix may successfully improve their transport to their target site of action. Pioneering research on probiotic lactic acid bacteria has mainly focused on their host effects. However, very little is known about their interaction with dairy ingredients. Such knowledge could contribute to designing new and more efficient dairy food, and to better understand relationships between milk constituents. The purpose of this review is first to provide an overview of the current knowledge about the biomolecules produced on bacterial surface and the composition of the dairy matter. In order to understand how bacteria interact with dairy molecules, adhesion mechanisms are subsequently reviewed with a special focus on the environmental conditions affecting bacterial adhesion. Methods dedicated to investigate the bacterial surface and to decipher interactions between bacteria and abiotic dairy components are also detailed. Finally, relevant industrial implications of these interactions are presented and discussed.

Milk sphingomyelin domains in biomimetic membranes and the role of cholesterol: morphology and nanomechanical properties investigated using AFM and force spectroscopy

Milk sphingomyelin (MSM) and cholesterol segregate into domains in the outer bilayer membrane surrounding milk fat globules. To elucidate the morphology and mechanical properties of theses domains, supported lipid bilayers with controlled molar proportions of MSM, dioleoylphosphatidylcholine (DOPC) and cholesterol were produced in buffer mimicking conditions of the milk aqueous phase. Atomic force microscopy imaging showed that (i) for T < 35 °C MSM segregated in gel phase domains protruding above the fluid phase, (ii) the addition of 20 mol % cholesterol resulted in smaller and more elongated l(o) phase domains than in equimolar MSM/DOPC membranes, (iii) the MSM/cholesterol-enriched l(o) phase domains were less salient than the MSM gel phase domains. Force spectroscopy measurements furthermore showed that cholesterol reduced the resistance of MSM/DOPC membrane to perforation. The results are discussed with respect to the effect of cholesterol on the biophysical properties of lipid membranes. The combination of AFM imaging and force mapping provides unprecedented insight into the structural and mechanical properties of milk lipid membranes, and opens perspectives for investigation of the functional properties of MSM domains during milk fat processing or digestion.

Butyric acid released during milk lipolysis triggers biofilm formation of Bacillus species

Bacillus species form biofilms within milking pipelines and on surfaces of equipment in the dairy industry which represent a continuous hygiene problem and can lead to serious economic losses due to food spoilage and equipment impairment. Although much is known about the mechanism by which the model organism Bacillus subtilis forms biofilms in laboratory mediums in vitro, little is known of how these biofilms are formed in natural environments such as milk. Besides, little is known of the signaling pathways leading to biofilm formation in other Bacillus species, such as Bacillus cereus and Bacillus licheniformis, both of which are known to contaminate milk. In this study, we report that milk triggers the formation of biofilm-related structures, termed bundles. We show this to be a conserved phenomenon among all Bacillus members tested. Moreover, we demonstrate that the tasA gene, which encodes a major portion of the matrix which holds the biofilm together, is vital for this process. Furthermore, we show that the free fatty acid (FFA) - butyric acid (BA), which is released during lipolysis of milk fat and demonstrates antimicrobial activity, is the potent trigger for biofilm bundle formation. We finally show that BA-triggered biofilm bundle formation is mediated by the histidine kinase, KinD. Taken together, these observations indicate that BA, which is a major FFA within milk triggers biofilm formation in a conserved mechanism among members of the Bacillus genus.

Phospholipid Architecture of the Bovine Milk Fat Globule Membrane Using Giant Unilamellar Vesicles as a Model

Giant unilamellar vesicles (GUVs) were constructed using an electroformation technique to mimic the morphology of the native milk fat globule membrane (MFGM) for the purpose of structural investigation. Bovine milk derived phospholipids were selected to manufacture GUVs which were characterized by confocal laser scanning microscopy after fluorescent staining. Circular nonfluorescent dark regions were observed in a 3/7 (mol/mol) surface mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3 phosphoethanolamine. Linear shaped dark lipid domains were found in GUVs containing sphingomyelin (SM) in the absence of cholesterol. The dark regions were interpreted as a gel phase formed by a high gel-liquid phase transition temperature (T_m) of DPPC and SM. This study provides a strategy for investigating the lipid structural organization within the native MFGM using a model lipid bilayer system and reveals that a SM and cholesterol association network is not the only requirement for nonfluorescent lipid domain formation and that PE is preferably located in the inner leaflet of the phospholipid bilayer.

Behavior of Heat-Denatured Whey: Buttermilk Protein Aggregates during the Yogurt-Making Process and Their Influence on Set-Type Yogurt Properties

The objective of this study was to assess the impact of using heat-denatured whey:buttermilk protein aggregate in acid-set type yogurt production. Whey and buttermilk (25:75) protein concentrate was adjusted to pH 4.6, heated at 90 °C for 5 min, homogenized and freeze-dried. Set-type yogurts were prepared from skim milk standardized to 15% (w/v) total solids and 4.2% (w/v) protein using different levels of powdered skim milk or freeze-dried protein aggregate. The use of the protein aggregate significantly modified yogurt texture, but did not affect the water-holding capacity of the gel. Confocal laser-scanning microscope images showed the presence of large particles in milk enriched with protein aggregate, which directly affected the homogeneity of the clusters within the protein matrix. Thiol groups were freed during heating of the protein aggregate suspended in water, suggesting that the aggregates could interact with milk proteins during heating.

Multiscale structures of lipids in foods as parameters affecting fatty acid bioavailability and lipid metabolism

On a nutritional standpoint, lipids are now being studied beyond their energy content and fatty acid (FA) profiles. Dietary FA are building blocks of a huge diversity of more complex molecules such as triacylglycerols (TAG) and phospholipids (PL), themselves organised in supramolecular structures presenting different thermal behaviours. They are generally embedded in complex food matrixes. Recent reports have revealed that molecular and supramolecular structures of lipids and their liquid or solid state at the body temperature influence both the digestibility and metabolism of dietary FA. The aim of the present review is to highlight recent knowledge on the impact on FA digestion, absorption and metabolism of: (i) the intramolecular structure of TAG; (ii) the nature of the lipid molecules carrying FA; (iii) the supramolecular organization and physical state of lipids in native and formulated food products and (iv) the food matrix. Further work should be accomplished now to obtain a more reliable body of evidence and integrate these data in future dietary recommendations. Additionally, innovative lipid formulations in which the health beneficial effects of either native or recomposed structures of lipids will be taken into account can be foreseen.

The effect of milk fat globules on adherence and internalization of Salmonella Enteritidis to HT-29 cells

Milk fat globules were extracted from bovine and goat milk and incubated with HT-29 human adenocarcinoma cells to assess the attachment and internalization of Salmonella Enteritidis. Because the expression of bacterial adhesins is highly affected by the presence of antibiotic, the attachment was studied with and without antibiotic in the cell growth medium. Although no inhibitory effect of the fat globules was observed in the presence of the antibiotic, milk fat globules significantly inhibited the binding and internalization of Salmonella in medium free of antibiotic. The fat globules from both bovine and goat milk markedly reduced bacterial binding and invasion compared with controls, and the cells treated with goat milk-derived fat globules demonstrated greater protective properties than those derived from bovine milk. The effect of heat treatment on bovine fat globules was also investigated, and it was shown that the fat globules from heated milk had a higher degree of inhibition than those from unheated milk.

Characterization of Lactobacillus reuteri interaction with milk fat globule membrane components in dairy products

A set of methods has been developed to study the adhesion between four Lactobacillus reuteri strains and the milk fat globule membrane (MFGM) components in dairy products. By combining sucrose density gradient (SDG) centrifugation and bacterial DNA quantification it was found which strains of L. reuteri were more strongly associated with the dairy products, and the results were corroborated by direct binding rate and force measurements made with optical tweezers. It was determined that strong binding was associated with hydrophobicity of the bacteria and that this hydrophobicity is correlated with the presence of LiCl-extractable protein on the surface of the bacteria. Confocal laser scanning microscopy (CLSM) allowed for the visualization of interactions between bacteria and MFGM. This study demonstrates that these methods can be used in combination to characterize, both qualitatively and quantitatively, the adhesion of lactic acid bacteria strains in dairy products.