Density is the weight of a substance per unit of volume, while specific gravity is the ratio between the density of the substance and that of water.
One approach to measuring specific gravity is a comparison of the weight of equal volumes of a liquid and water in standardized glassware, a pycnometer.
The specific gravity of milk bears a relationship to butterfat and total solids, so it has been used as an aid to detecting gross abnormalities from the average composition.
Given that the density of any substance varies with temperature, it is important to specify temperature when showing the results.
On the average the specific gravity of milk at 15 ° C/15 ° C is 1.032 (1.028-1.035). It is the result of the specific gravities of each of its components.
Yoghurt milk and other dairy mixes containing sugar and added milk solids exhibit higher density and specific gravity than milk. For instance, the specific gravity of ice cream mix is 1.0544 – 1.1232.
The specific gravity of milk varies somewhat with breed,. Milk for Ayrshire cows has a mean specific gravity of 1.0317 while that of Jersey and Holstein milks is 1.0330.
The specific gravity of whole milk decreases slightly with increasing temperature, partly because of the effect of temperature on milk butter but also because the contraction of the other solids that occur on mixing with water decreases slightly with increasing temperature.
Specific gravity of milk
