Nutraceutical Properties of Milk Fat Globular Membrane

Abstract

Milk fat globule membrane (MFGM) is a protein-lipid biopolymer that originates from the apical surface of mammary epithelial cells and surrounds fat globules in milk. During milk synthesis, fat droplets originate in the endoplasmic reticulum and travel directly to the cell’s apical surface. As they travel from the epithelial cells into the alveolar lumen, they pass through the apical membrane and are encapsulated in the plasma membrane complete with the exterior glycocalyx resulting in discrete globules. These milk fat globules have a nonpolar lipid core composed primarily of triglycerides that is surrounded by the MFGM which contains both membrane polar lipids and glycoproteins. While MFGM is in all dairy products containing milk fat, it is especially enriched in churn buttermilk, a co product of butter production. When milk fat is churned, the membrane surrounding the fat globules is disrupted, and the free fat released from the globules coalesces. This process ultimately results in a solid fat phase, butter, and an aqueous phase, also known as churn buttermilk. This material, buttermilk, has a long history of anecdotal health-promoting associations, yet it does not currently generate any added value in the market place for delivering nutritional benefit. MFGM has recently been shown in lipidomic and proteomic characterizations to have an interesting carbohydrate, lipid and protein profile. The phospholipids and membrane glycoproteins found in MFGM likely interact extensively with the gut epithelia during digestion, both physically and biochemically. Moreover, MFGM has a relatively high concentration of sphingolipids, which in purified form have been demonstrated to be protective against colon cancer. The unique composition of MFGM has led to the idea that it may have remarkable nutraceutical properties, however, few studies have tested this hypothesis. Recent studies from our laboratory have demonstrated that dietary MFGM improves gut barrier function in cell and animal models and is protective against colon cancer in a rodent model. In this chapter we will discuss the isolation, composition, biochemical properties and intestinal health promoting effects of the biopolymer MFGM.