The Physics
An encyclopedia of scientific essays

Density of Milk

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Bibliographic Entry Result
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Weight Density and Specific Gravity of Various Liquids. 1998 Pump.Net. May 29, 2002. "Milk has a weight density of 64.2 to 64.6. [Lbs. per Cu. Ft.]" 1028–1035 kg/m3
Specific Gravity of Various Materials Compiled By the Engineering Group. Delta Controls Corporation Engineered Sensors for Difficult Services. May 29, 2002.
Milk 64.4 1.035
1035 kg/m3
Dairy Chemistry and Physics. Douglas Goff. University of Guelph. "With all of this in mind, the density of milk varies within the range of 1027 to 1033 kg m(-3) at 20° C. [see table below]" 1027–1033 kg/m3
I also determined the density of milk myself. [see calculation at bottom of page] 1037 kg/m3
The following table gives the density of various fluid dairy products
as a function of fat and solids-not-fat (SNF) composition:
  Composition Density (kg/L) at:
Product Fat (%) SNF (%) 4.4 °C 10.0 °C 20.0 °C 38.9 °C
Producer milk 04.00 08.95 1.035 1.033 1.030 1.023
Homogenized milk 03.60 08.60 1.033 1.032 1.029 1.022
Skim milk, pkg 00.02 08.90 1.036 1.035 1.033 1.026
Fortified skim 00.02 10.15 1.041 1.040 1.038 1.031
Half and half 12.25 07.75 1.027 1.025 1.020 1,010
Half and half, fort. 11.30 08.90 1.031 1.030 1.024 1.014
Light cream 20.00 07.20 1.021 1.018 1.012 1.000
Heavy cream 36.60 05.55 1.008 1.005 0.994 0.978

Milk is a very nutritious and versatile food. People enjoy drinking milk in its natural form and also use it to make a wide range of food products, including cream, butter, yogurt, cheese, and ice cream. We drink the milk produced from a variety of domesticated mammals, including cows, goats, sheep, camels, reindeer, buffaloes, and llama. The major source for commercial production and consumption is from cows.

Most milk is composed of 80 to 90 percent water. The remaining 10 percent consists of the major nutrients needed by the body for good health, including fats, carbohydrates, proteins, minerals, and vitamins. Cow milk contains approximately 87% of water, 3 to 4% protein, 4 to 4.5% fat, and approximately 4.5% milk sugar (lactose). It typically contains about 3.5 to 5 percent fat, which is dispersed throughout the milk in globules. Fat supplies taste and texture, and vitamins A, D, E, and K, as well as certain fatty acids that the body is unable to produce. Lactose is a kind of sugar found only in milk and gives milk its sweet taste. It makes up about 5 percent of milk's content.

If the fat content is lowered to 3.25 percent, the milk is sold as whole milk. Low-fat milk typically has 1 percent or 2 percent fat. Since fat has a lower specific gravity and therefore is "lighter" than the milk serum, fat globules rise to the milk surface. Then, fat can be collected or skimmed from the milk. The fat thus collected is called "cream" and the milk deprived of fat is called "skimmed milk"or "skim milk". As the lighter milk fat rises to the surface, the density changes. As you go towards the surface it creates layers of decreasing density. When milk is left to stand long enough, some separation will occur because of density differences.

Cream or milk fat is lighter in density than water and floats on the surface of un-homogenized milk. When you skim off the surface, some of the fat, the denser portions remains and the milk is denser. This explains why skim milk is denser.

Alicia Noelle Jones -- 2002