How Is Fat Separated From Milk to Make Skim Milk?

Skim milk is a lower-fat alternative to whole milk.
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You love the taste of milk, but you don't love the idea of how high in fat traditional whole milk is. Because skim milk has had dairy fat removed from it, you can enjoy milk's benefits without boosting your fat intake. Milk packagers utilize a variety of techniques to separate milk fat, allowing you to enjoy a cold glass of this calcium-filled drink.

Creaming Separation

    If milk is left to stand for between 30 and 40 minutes, the fat will naturally separate, according to the International Livestock Research Institute. This process is known as creaming and uses the principles of gravity to bring fat globules together and cause them to rise. Manufacturers can temporarily increase milk's temperature to between 20 and 50 degrees Celsius to help speed the process, because the higher temperatures cause the fat to come together more quickly. The fat portion can then be skimmed off the top.

Gravity Separation

    If the idea of waiting 30 to 40 minutes to separate milk fat sounds too long, a faster option exists: centrifugal separation. This milk separation method requires a centrifuge -- a machine that spins at a very fast rate. When milk is placed into a centrifuge, the force of gravity is about 5,000 to 10,000 times greater than the Earth's gravitational pull, according to the International Livestock Research Institute. Milk centrifuge separators have different channels where the fat and skim milk portions are separated and collected. Another benefit of the centrifuge method is that particles such as bacteria also can be separated.

Nutrient Composition

    The results of milk fat separation for skim milk production can reduce fat and calories without removing calcium, a mineral vital for healthy bones. For example, whole milk contains 3.34 grams of fat, while skim milk has 0.18 grams of fat, according to Encyclopaedia Britannica. Milk packagers can set the desired fat content when using the centrifuge process. Skim milk must be less than 0.5 percent milk fat, but most skim milk contains less than that. Skim milk also has about 26 fewer calories than whole milk.

Skip the Fat?

    While skim milk can be a healthy low-fat selection, there are times when milk fat is beneficial. For example, children and older adults may need the extra fat that comes from drinking whole milk, according to Fox News. Also, removing fat to produce skim milk can remove nutrients commonly contained in milk fat, such as vitamins A and D. Although most skim milk formulations have these vitamins added, read nutrition labels carefully to ensure these nutrients have been added.

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