Casein precipitation by acid and rennet coagulation of buttermilk: Impact of pH and temperature on the isolation of milk fat globule membrane proteins

An absolute quantification method for selected MFGM proteins in infant formula using targeted proteomics

Milk fat globule membrane (MFGM) proteins are receiving increased attention due to their reported benefits for human health, particularly in infant populations. Challenges exist in MFGM protein quantification due to their low quantities, complex chemistry, interactions with other matrix components, and the high matrix complexity. In this study, a subset of four MFGM proteins were selected as relevant targets for identification and quantification in an infant formula (IF) matrix: butyrophilin, mucin 1, xanthine dehydrogenase/oxidase, and perilipin 2. An analytical protocol for absolute quantification of these four MFGM proteins in IF was successfully developed and validated. Additionally, the feasibility to apply the method in selected MFGM ingredients was also demonstrated. The method demonstrated good performance; high accuracy and robustness, low LOQ and uncertainty, while controlling the matrix effect. This study represents a report of an analytical method to quantify selected MFGM proteins in IF.

A hybrid catalyst-triggered cascade reaction for cholesterol detection using a smartphone-based miniature fluorescent apparatus

A new hybrid biological-chemical catalyst, magnetic nanoparticles functionalized with cholesterol oxidase (Fe3O4/APTES/ChOx), was developed for cholesterol detection. In the presence of cholesterol, the enzyme produced H2O2, which facilitated the generation of fluorescent molecules from the fluorogenic substrate with the assistance of Fe3O4 nanoparticles. A smartphone camera with a miniature fluorescent apparatus was used to assess fluorescence emission. Then, a smartphone application was employed to translate the fluorescence intensity to the red, green, and blue (RGB) domain. The developed approach achieved excellent selectivity and acceptable performances while supporting an onsite analysis approach. The practical operational range spanned from 5 to 100 nM, with a detection limit of 0.85 nM. Fe3O4/APTES/ChOx was applied for up to four replicates of reuse and demonstrated stability for at least 30 days. The applicability of the method was evaluated in milk samples, and the results were in accordance with the reference method.

Milk fat globule membrane proteins are crucial in regulating lipid digestion during simulated in vitro infant gastrointestinal digestion

Products of lipolysis released during digestion positively affect the metabolism of newborns. In contrast to the 3-layer biological membranes covering human milk (HM) fat, the lipid droplets in infant milk formula (IMF) are covered by a single membrane composed of casein and whey proteins. To reduce the differences in lipid structure between IMF and HM, studies have used milk fat globule membrane (MFGM) components such as milk polar lipids (MPL) to prepare emulsions mimicking HM fat globules However, few studies have elucidated the effect of membrane proteins (MP) on lipid digestion in infants. In this study, 3 kinds of emulsions were prepared: One with MPL as the interfaced of lipid droplets (RE-1), one with membrane protein concentrate (MPC) (RE-2) as the interface of lipid droplets, and one with both MPL and MPC (1:2) as the co-interface of lipid droplets (RE-3). The interfacial coverage of the emulsions was confirmed by measuring the contents of MPL and MPC at the lipid droplet interface, and by confocal laser scanning microscopy analyzed. By controlling the homogenization intensity, the specific surface area of lipid droplets was controlled at the same level among the 3 emulsions. The stability constants of the emulsions varied, and RE-1 was the most stable. During simulated in vitro infant gastrointestinal digestion, the amount of free fatty acids (FFA) released from the lipid droplets was significantly higher from those with MPC at the interface (RE-2, RE-3) than from that with MPL at the interface (RE-1). The amount of FFA released at the end of intestinal digestion of RE-1, RE-2, and RE-3 was 255.00 ± 3.54 µmol,328.75 ± 5.30 µmol, 298.50 ± 9.19 µmol, respectively. Compared with the lipid droplets in RE-2, those with MPL at the interface (RE-1, RE-3) released more unsaturated fatty acids (USFAs) during digestion. The emulsifying activity index was highest in RE-3 (MPL and MPC co-interface). The presence of MPL at the emulsion interface increased the release of USFAs, while the presence of MPC increased the release of FFA. These results show that both MPL and MP are indispensable in the construction of MFGM. Understanding their effects on digestion can provide new strategies for the development of infant foods.

Lipidomic Comparisons of Whole Cream Buttermilk Whey and Cheese Whey Cream Buttermilk of Caprine Milk

Buttermilk is a potential material for the production of a milk fat globule membrane (MFGM) and can be mainly classified into two types: whole cream buttermilk and cheese whey cream buttermilk (WCB). Due to the high casein micelle content of whole cream buttermilk, the removal of casein micelles to improve the purity of MFGM materials is always required. This study investigated the effects of rennet and acid coagulation on the lipid profile of buttermilk rennet-coagulated whey (BRW) and buttermilk acid-coagulated whey (BAW) and compared them with WCB. BRW has significantly higher phospholipids (PLs) and ganglioside contents than BAW and WCB. The abundance of arachidonic acid (ARA)- and eicosapentaenoic acid (EPA)-structured PLs was higher in WCB, while docosahexaenoic acid (DHA)-structured PLs were higher in BRW, indicating that BRW and WCB intake might have a greater effect on improving cardiovascular conditions and neurodevelopment. WCB and BRW had a higher abundance of plasmanyl PL and plasmalogen PL, respectively. Phosphatidylcholine (PC) (28:1), LPE (20:5), and PC (26:0) are characteristic lipids among BRW, BAW, and WCB, and they can be used to distinguish MFGM-enriched whey from different sources.

Proteomic Comparisons of Caprine Milk Whole Cream Buttermilk Whey and Cheese Whey Cream Buttermilk

Buttermilk, a potential material used to produce milk fat globule membrane (MFGM), is obtained as a byproduct of butter making from milk whole cream and cheese whey cream. This study investigated the effects of rennet and acid coagulation on the protein profiles of buttermilk rennet-coagulated whey (BRW) and buttermilk acid-coagulated whey (BAW). They were compared to those of whey cream buttermilk (WCB). Rennet coagulation was more efficient in removing casein, while retaining more IgG and lactoferrin than acid coagulation. BRW had more MFGM than BAW. Butyrophilin, xanthine dehydrogenase, and mucin1 were significantly higher (P < 0.05) in BRW, while fatty acid-binding protein 3 was enriched in BAW. KEGG analysis showed that complement and coagulation cascades had the greatest differences, and the abundance of proteins involved in this signaling pathway in BRW and BAW was higher, suggesting their potential anticoagulant and anti-inflammatory activity. BAW had higher apolipoprotein A4 and transcobalamin 2, which are essential carriers for transporting long-chain fatty acids and vitamin B12 from the intestine to the blood. Therefore, BAW intake might improve lipids and vitamin B12 absorption. This study can help deepen the understanding of protein composition of MFGM-enriched whey and facilitate the production of MFGM proteins for infants and old-aged populations.

Label-free quantitative proteomic analysis of milk fat globule membrane proteins in porcine colostrum and mature milk

Milk fat globule membrane (MFGM) proteins are nutritional components with various biological functions. This study aimed to analyze and compare MFGM proteins in porcine colostrum (PC) and porcine mature milk (PM), via label-free quantitative proteomics. In total, 3917 and 3966 MFGM proteins were identified in PC and PM milk, respectively. A total of 3807 common MFGM proteins were found in both groups, including 303 significant differentially expressed MFGM proteins. Gene Ontology (GO) analysis revealed that the differentially expressed MFGM proteins were mainly related to the cellular process, cell, and binding. The dominant pathway of the differentially expressed MFGM proteins was related to the phagosome according to Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. These results reveal crucial insights into the functional diversity of MFGM proteins in porcine milk during lactation and provide theoretical guidance for the development of MFGM proteins in the future.

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.

Alternatives to Cow’s Milk-Based Infant Formulas in the Prevention and Management of Cow’s Milk Allergy

Cow’s milk-based infant formulas are the most common substitute to mother’s milk in infancy when breastfeeding is impossible or insufficient, as cow’s milk is a globally available source of mammalian proteins with high nutritional value. However, cow’s milk allergy (CMA) is the most prevalent type of food allergy among infants, affecting up to 3.8% of small children. Hypoallergenic infant formulas based on hydrolysed cow’s milk proteins are commercially available for the management of CMA. Yet, there is a growing demand for more options for infant feeding, both in general but especially for the prevention and management of CMA. Milk from other mammalian sources than the cow, such as goat, sheep, camel, donkey, and horse, has received some attention in the last decade due to the different protein composition profile and protein amino acid sequences, resulting in a potentially low cross-reactivity with cow’s milk proteins. Recently, proteins from plant sources, such as potato, lentil, chickpeas, quinoa, in addition to soy and rice, have gained increased interest due to their climate friendly and vegan status as well as potential lower allergenicity. In this review, we provide an overview of current and potential future infant formulas and their relevance in CMA prevention and management.

Properties of Sweet Buttermilk Released from the Churning of Cream Separated from Sheep or Cow Milk or Sheep Cheese Whey: Effect of Heat Treatment and Storage of Cream

The objective of the study was to compare the buttermilk released from the churning of sweet cream separated from sheep milk (BSM) or whey (BSW) with the buttermilk from sweet cow milk cream (BCM). Additional experimental factors were the heat treatment (68 °C for 10 or 30 min) and storage of cream (refrigeration or freezing). The composition of BSM was the most advantageous in terms of non-fat solids, protein-which was the most abundant solid component-casein, calcium and phosphorus contents. No significant differences were observed in the phospholipids (PL) content of BSM, BCM and BSW. Antioxidant potential and emulsion stability (ES) of BSM were the highest. The radical scavenging activity (RSA) of BSW was high opposite to chelating activity (CA). Some functional properties of BSW were similar to those of BSM and BCM. The freezing of cream affected the churning, the fat content, the soluble nitrogenous fraction at pH 4.6 (WSN) and some functional properties of buttermilk, but not in a consistent manner. The properties of BSM were marginally affected or unaffected by the use of frozen cream. The freezing of whey cream caused significant changes (p < 0.05) in the protein profile and the functional behaviour of BSW. Cream heat treatment affected the WSN of BSW opposite to its sweet cream counterparts.

Bioactives in bovine milk: chemistry, technology, and applications

The significance of dairy in human health and nutrition is gaining significant momentum as consumers continue to desire wholesome, nutritious foods to fulfill their health and wellness needs. Bovine milk not only consists of all the essential nutrients required for growth and development, it also provides a broad range of bioactive components that play an important role in managing human homeostasis and immune function. In recent years, milk bioactives, including α-lactalbumin, lactoferrin, glycomacropeptide, milk fat globule membrane, and milk oligosaccharides, have been intensively studied because of their unique bioactivity and functionality. Challenges for the application of these bioactive components in food and pharmaceutical formulations are associated with their isolation and purification on an industrial scale and also with their physical and chemical instability during processing, storage, and digestion. These challenges can be overcome by advanced separation techniques and sophisticated nano- or micro-encapsulation technologies. Current knowledge about the chemistry, separation, and encapsulation technology of major bioactives derived from bovine milk and their application in the food industry is reviewed here.

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.