Goat Milk | Lipids of Goat Milk

The cow and goat milk differs significantly in the physico - chemical structure and composition of milk fats. The average size of fat globule of goat milk is about 3.5 micrometers as compared to 4.5 micrometers for cow milk fat. Average diameters of fat globules for goat, cow, buffalo, and sheep milks were reported to be 3.49, 4.55, 5.92, and 3.30 micron respectively.

Smaller fat globules make a better dispersion and helps in formation of more homogeneous mixture of fat in goat milk. This in turn would provide lipases with a greater surface area of fat for enhanced lipolytic or digestive action. Natural homogenization of goat milk would be better for digestion from a human health standpoint than the mechanically homogenized cow milk products. The smaller physical size of fat globules in goat milk appears to be associated with poor creaming abilit, i.e. due to lack of agglutinins in goat milk, the fat globules do not clump together when it is chilled.

Of the total milk fat present in the goat milk, 97–99% exists as of free lipids and 1–3% in bound form. The ratio of bound to free lipids is comparable to that for cow milk. Fractional compositions of free lipids of goat milk are similar to those of cow milk. Free lipids of goat milk contained 96.8% triglycerides, 2.2% diglycerides, and 0.9% monoglycerides, whereas bound lipids contained 46.8% neutral lipids and 53.2% polar lipids (8.5% glycolipides and 44.7% phospholipids).

In the light of skim milk fraction, goat milk displayed almost a double amount of free lipids as compared to cow counterparts, whereas the opposite trend was found for bound lipids of both goat and cow milks. Polar lipids make up approximately 1.6% of the total lipids. Of the polar lipid fraction, glycolipids make up 16% in goat milk as compared to the 6% in cow milk. Quantitative analysis of the phospholipid fraction of bound lipids of goat milk revealed that it had 35.4% phosphatidyl ethanolamine, 3.2% phosphatidyl serine, 4.0% phosphatidyl inositol, 28.2% phosphatidyl choline, and 29.2% sphingomyelin. Species differences in phospholipid fractions appear to be insignificant. Holding goat milk for 1–2 days at 4°C increased the phospholipids and cholesterol in the skim milk fraction, probably as a result of damage to the fat globules. Owing to this reason, more neutral lipids would be retained in the skim milk.

The fatty acid composition of goat milk reveals the presence of higher concentration of short and medium chain fatty acids, which are thought to be responsible for the characteristic “goaty odour” in goat milk. But, the silver lining is that they are amenable to heat treatment and hence pasteurization of milk removes the defect.

Another group of scientists refute this claim and state that the presence of buck during milking of does is responsible for the absorption of the odour produced from the glands of buck. But however, this hypothesis is not yet proved.