Fat
Milk contains fat in emulsion; that is, the fat is suspended in the serum of milk in the form of emulsion. The fat is lighter than the milk serum and therefore rises to the top in the form of cream, or the fat may be separated from the milk by centrifugal force. Cream does not consist in fat globules alone but contains the same constituents as the milk, only it is very much richer in fat. By agitating the cream, as in a churn, or by means of shaking, the fat globules will coalesce and form into lumps of butter. It is stated by some authors that cream contains a larger number of bacteria than skim milk. The fore milk, or that which is first milked from the udder, has a small amount of fat; the last that is taken, which is known as the strippings, may contain as much as 9% or 10% of fat. An increase in the temperature of the milk will retard the rising of the fat and if the temperature is kept above 65° C. for any length of time, cream will not form on top. Therefore, it follows that a moderately low temperature will increase the rapidity with which fat rises to the top of the milk.
Parkes says, “Milk should not have less than 12.5% of total solids of which 3.5% is fat and 0.7% is salts; ... the percentage of cream by volume not less than 10%.”
Infants placed on a diet of milk that is too rich in fats will thrive for a while, but in time will lose weight and show other symptoms, indicating the inability of Innate to digest the food. The stools become hard and dry, of a pale color and composed largely of fat soaps. This shows that Innate is unable to furnish sufficient alkaline bases through the body to saponify the excessive amount of fat in the intestines. This results in a condition resembling acidosis.