Langmuir film balance- A technique to study the interaction of β-cyclodextrin with cholesterol in milk fat globule membrane monolayers

Milk is a natural complex system present as oil in water emulsion. The natural organisation of milk fat globules is stabilized by the presence of a natural membrane, called the milk fat globule membrane (MFGM). It has tripartite structure consisting of a monolayer facing the inner triacylglycerol core and an external bilayer. This MFGM accounts for 2-6% of fat globule. The MFGM is composed of both polar lipids and proteins. Cholesterol is also present in MFGM and accounts for about 2% of MFGM. Langmuir film balance is a technique to study monolayers and is a useful tool to examine the effect of cholesterol removal on surface properties of MFGM. β-cyclodextrin has no surface activity of its own and is thus a useful tool to study the effect of cholesterol desorption on surface properties in membrane. The removal of monolayer cholesterol to the sub-phase is proportional to the area decrease of the monolayer at a constant surface pressure. Amount of cholesterol removed can also be calculated as a function of mean molecular area at a given pressure, time and temperature. Using the monolayer technique, it is possible to study the interactions between β-cyclodextrin and MFGM film as well as effect of cholesterol removal in altering the surface properties MFGM.