What are the sources of MFGM?
Natural Mammalian Milk
The most fundamental and natural source of MFGM is the milk produced by mammals. MFGM is formed within the mammary epithelial cells during lactation, surrounding the milk fat globules before they are secreted into the milk. This process is unique to mammalian milk, distinguishing it from non-dairy food sources.
- Human Milk: For human infants, breast milk is the most bioavailable source of MFGM. The composition and abundance of MFGM in human milk can vary depending on the mother's diet and stage of lactation. MFGM from human milk is rich in specific proteins and lipids that are crucial for infant neurodevelopment, immune function, and gut health.
- Bovine Milk: Cow's milk is another primary source of MFGM and is the most common raw material used for commercial MFGM products. While similar in overall structure, bovine MFGM has a different protein and lipid profile compared to human milk.
- Other Mammalian Milk: Milk from other mammals like goats and sheep also contains MFGM, though with species-specific variations in composition and fat globule size.
Processed Dairy Products
During dairy manufacturing, MFGM is often disrupted and re-distributed into different fractions. This processing makes certain dairy by-products exceptionally rich sources of MFGM components.
- Buttermilk: When cream is churned to make butter, the fat globule membranes are disrupted. The MFGM fragments and their bioactive components are released into the buttermilk, the liquid left over from the churning process, making it a concentrated source.
- Whey: As a by-product of cheesemaking, whey also contains residual fat rich in MFGM components. MFGM from whey can be further processed into whey protein concentrates (WPC) and isolates (WPI).
- Cream Serum and Butter Serum: These are aqueous phases that separate during the production of anhydrous milk fat (butter oil). They are known to have high concentrations of MFGM and polar lipids.
- Yogurt and Fresh Cheese: Because the MFGM is preserved to some extent in liquid milk and less processed dairy foods, yogurt and fresh cheese made from whole milk can contain MFGM components, although often altered by heat treatments.
Commercial Isolation and Applications
Advancements in dairy technology have enabled the extraction and concentration of MFGM from dairy by-products for use in nutritional products. This is particularly important for infant formula development, where mimicking breast milk composition is a key goal.
Commercial MFGM-enriched ingredients are created using membrane separation techniques like microfiltration and diafiltration. These ingredients are used to supplement infant formula and other functional foods. The composition of these commercial ingredients can vary significantly depending on the source material (whey or cream) and the extraction process.
Key Factors Affecting MFGM Content
Several factors can influence the quantity and characteristics of MFGM in dairy products, making standardization a challenge.
- Species and Lactation Stage: The milk source is a major determinant. Human and bovine MFGM have different protein and lipid profiles. The stage of lactation also affects MFGM, with colostrum having different properties than mature milk.
- Processing Techniques: Industrial processes like homogenization, pasteurization, and churning can significantly alter the MFGM's structure and composition. High-heat treatments can cause whey proteins to bind to the MFGM, while homogenization breaks down fat globules, releasing MFGM fragments.
- Genetic and Environmental Factors: For bovine milk, factors such as breed and diet influence MFGM composition. For human milk, maternal diet and geographical location can cause variations.
Human MFGM vs. Bovine MFGM: A Comparison
| Feature | Human MFGM | Bovine MFGM |
|---|---|---|
| Source | Human breast milk | Cow's milk, dairy by-products |
| Availability | Breastfeeding | Widely available commercially via dairy processing |
| Fat Globule Size | Wide size range (0.35–13 μm) | Narrower average size range (2.5–5.7 μm) |
| Key Lipids | Phospholipids (especially Sphingomyelin, SM), gangliosides | Phosphatidylcholine (PC), phosphatidylethanolamine (PE), SM |
| Key Proteins | Mucin 1, Butyrophilin (BTN), Xanthine Oxidase (XO), Lactadherin | Butyrophilin (BTN), Xanthine Oxidase (XO), Lactadherin, Mucin 1 |
| Compositional Balance | Proportions of proteins and lipids vary, e.g., higher SM content reported in human MFGM. | Overall composition differs, e.g., potentially higher BTN and lower XO ratio compared to human milk. |
| Dietary Impact | Composition can be influenced by the mother's diet. | Composition can be influenced by the cow's diet, breed, and season. |
Conclusion
The sources of MFGM are exclusively mammalian milk and its derivatives. Human milk is the most natural source, providing MFGM and its bioactive components directly to infants. Industrially, MFGM is concentrated from dairy by-products like buttermilk and whey, which are generated during butter and cheese manufacturing. These MFGM-enriched ingredients are then used to fortify infant formulas and other functional foods to provide many of the benefits associated with breast milk, such as improved cognitive development, immune support, and gut health. While differences exist between human and bovine MFGM, the development of commercial MFGM sources has made these beneficial components more widely available. Understanding these various sources is key to appreciating the complex nutritional value of milk and its derivatives.
An extensive review on MFGM can be found on the National Institutes of Health website at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6232911/.
