Milk 102: Pasteurization & Homogenization

milk pasteurization machine and vat

Health Disclaimer: Health and related lifestyle choices (including diets and dietary needs) are extremely individualistic. Please consult with your doctor before making any lifestyle changes.

The Pasteurization Process

Back in the day milk was delivered directly from the farm to the consumer’s front door. Milk was milk and there weren’t as many options that we have available to us today. Back then consumers could only get raw (unpasteurized) whole milk.

xIt wasn’t until after the French microbiologist Louis Pasteur developed the process of pasteurization (heating up milk to destroy pathogens and microorganisms), the U.S. Food and Drug Administration (FDA) decided to enforce milk to be pasteurized prior to distribution and sale across the US.

There are actually a few different forms of pasteurization being vat pasteurization and holding method. The holding method also include subcategories High Temperature Short Time (HTST), Higher Heat Shorter Time (HHST), Ultra High Temperature (UHT), and Ultra Pasteurized (UP).

In addition to killing harmful bacteria, another benefit of pasteurization is extended shelf life. Depending upon the pasteurization method used and storage conditions, pasteurized milk may last from a couple weeks up to several months.

Although pasteurized milk is generally considered safer to consume than raw milk, the process of pasteurization is also known to destroy some of the good nutritional properties found in unpasteurized milk (see Milk 103: Raw Milk for more information on raw milk).

FAQ: Is Kilgus Farmstead milk pasteurized?

Yes, Kilgus Farmstead milk that is distributed is pasteurized according to Illinois food safety laws. Using the HTST pasteurization method, our milk is heated to 163°F for 15 seconds which destroys any harmful bacteria that may be present in the milk.

Got more questions? Visit our FAQ page.

heavy cream milk jug with cap - shake well


Too often pasteurization and homogenization get confused or are wrongly considered to be the same, when in fact they are entirely different processes with completely different goals.

Pasteurization, as we have learned, is the process of heating up milk to kill bacteria in order make it safer to drink. Homogenization, on the other hand, is about keeping milk from separating.

If you have ever seen or had fresh milk that has not been homogenized (Kilgus Farmstead milk), what you will notice is that the milk will separate and the cream (also called milk fat or creamline) will raise to the top. This happens because milk is actually made up of both liquids and solids.

Quick Tip: Shake It Up!

Before drinking non-homogenized milk be sure to shake the container first. The act of shaking will redistribute the cream throughout the milk making it rich and even throughout.

skimming cream off the top of a mason jar filled with milk using a wooden spoon

The liquid part of milk is mostly comprised of water whereas the solid contains most of the nutritional elements found in milk. Furthermore, because the liquid is denser and therefore heavier than the cream, the cream tends to float to the top. Just like trying to mix oil and water, the oil (which is another form of fat) will always rise to the top.

The homogenization process was invented to keep milk from separating. This is achieved by breaking down the larger milk fat particles into smaller particles and then mixing and dispersing them evenly throughout the liquid. The result of the process is that the milk fat remains suspended in the liquid instead of separating. In other words, the cream no longer raises to the top.

It should also be noted that because the amount of milk fat present in milk varies between whole, 2%, 1%, and skim, non-homogenized whole milk will have more cream and separation in comparison to the others. By contrast, non-homogenized skim milk will have no separation because it is fat free. Between homogenized and non-homogenized milk, most milk found at local retailers and grocery stores will be homogenized unless otherwise noted on the label.

FAQ: Is Kilgus Farmstead milk homogenized?

We do not homogenize our milk and as a result, the milk fat or cream of the milk will raise to the top if it has been left sitting for a period of time. Simply shake the container which will redistribute the cream, pour, and enjoy!

Got more questions? Visit our FAQ page.

Go to part three: Milk 103: Raw Milk ➡️