Skim of low-fat milk

Dry milk was referred to as milk powder until the mid 1960s, when the designation was changed by the American Dry Milk Institute to dry milk in the United States.

Large quantities of skim of low fat milk are dried. This may be done by spraying atomized droplets of milk into chamber through which heated air is circulated (spray drying).

The atomizers used in this process include mainly rotary and pressure types. The final articles size of the dried powder produced by utilizing a rotary atomizer and the basic plant is greater than 1000 microns.

The milk also may dry by allowing it to flow over the surface of two heated metal drum that rotate toward each other.

A thin layer or film of product is dried over an internally steam-heated drum with steam pressure up to 620 kPa and 149 °C. Approximately 1.2 – 1.3 kg steam are required per kilogram of water evaporated.

The dried milk then is scraped from the drum surface, as they rotate, by metal scraper.

The operating variables for a drum dryer include condensation of incoming product in an elevator, temperature of incoming product, steam pressure in drum, speed of drum, and height of product over drum.

Dried milk (usually the spray dried type that contains about 5% of moisture) may be re-humidified to slightly higher moisture content after drying.

It has poor dissolving properties and where sold for domestic use is subjected to further instantisation, which agglomerates granules and leads to a faster dissolution time.
Skim of low-fat milk

Low fat milk processing

Centrifuge or milk separator is designed to separate the cream from the milk as soon as drawn from the cow.

The milk is heated in a plate heat exchanger to approximately 57° C and subsequently separated into a high fat fraction and low fat fraction.

The centrifuges rotates at a high speed and this facilities the separation of oil or fat from the milk. Fat being lighter floats to the top and the remaining milk solution being heavy remains at the bottom.

The fat rich cream after skimmed off is to be used for the manufacturer of butter, butter oil, ghee or other fat rich products.

The principle used in separation by centrifugation is the difference in the density of the component of a mixtures.

The process of separating has not really changed since the first invention of the centrifuge at the end of the nineteenth century. However, the reliability of equipment and the scale at which these process are run are far beyond the imagination of the inventors.

Low fat milk are as nutritious as whole milk, but contain much less fat and cholesterol than whole milk. Low fat milks may contain 1% or 2% fat. Because fat soluble vitamins are removed when fat is separated, the new federals standard for low fat milk required addition of vitamin A.

The lower fat content drops the calories to 199 per cup.
Low fat milk processing