Biological Significance of Native Globules

In some milk fat globules, small aqueous compartments are located beneath the membrane bilayer, which have been termed cytoplasmic crescents (Huston and Patton, 1990). Whether or not this cytoplasmic inclusion provides some benefit is unknown. Yet, as this aqueous compartment is protected from the bulk serum phase by the MFGM, constituents located therein are presumably afforded some protection, at least initially, from gastric hydrolysis. Huston and Patton (1990) found crescents in all samples of milk they examined, and they were more prevalent in human (7.3% of globules), than in bovine (1% of globules) milk. Furthermore, there was considerable individual and diurnal variation. The structure of a cytoplasmic inclusion, surrounded by an intact plasma membrane on one side and a fat globule surface on the other, may allow certain labile constituents to be protected until they reach their proper site of bioactivity. At this point it is not known whether the crescents have a purpose or are simply the result of inefficiencies in the secretion process. As it is possible to isolate milk preparations enriched in cytoplasmic crescents, there is an opportunity to determine the nature of the materials found within. This unusual biocompartment may prove to be a model of food structure for biodelivery. 

MFGM Consumption Studies Physiological and Nutritional Effects 

The diets used in these initial studies on the effect of consuming buttermilk on serum cholesterol were not standardized, and involved a small number of individuals. Hussi et al. (1981) fed a large group of healthy volunteers with either 2.7 L/day of skim milk or 2 L/day of buttermilk or a control diet for three weeks. All diets were standardized for macronutrient and energy level, and all volunteers consumed the control diet for 3 weeks prior to the study. No significant differences were found in the serum lipid or lipoprotein profiles between the control and test groups. 

The ability of MFGM to inhibit intestinal (3-glucuronidase activity was measured by Ito et al. (1993). This enzyme is a product of colonic 

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