What’s the Difference between Homogenization and Pasteurization?

When visitors tour our farm, I frequently get questions about milk terminology so I thought my blog readers might have the same questions. I enlisted the help of the Dairy Dictionary on the Dairy Farming Today website for definitions of commonly used “milk” terms. I’ve added some details specific to our farm in italics.

Bulk Tank - A refrigerated, stainless steel storage tank located at the dairy, designed to hold milk as soon as it leaves the cow. The milk is cooled immediately in the bulk tank, usually to 35-39 degrees F. The milk is then collected by a bulk tank truck and shipped to a processing plant. We have two 4,000 gallon bulk tanks at our farm where we store milk until the milk truck picks it up once a day.  

Me with our two bulk milk tanks

Butterfat - Also known as milkfat, this is the fatty portion of milk. Milk and cream are often sold according to the amount of butterfat they contain. In the United States, there are federal standards for butterfat content of dairy products. The milk from our Holstein cows averages 3.5% to 3.6% butterfat annually.

Our cows being milked in the milking parlor

Cream - Milk is separated by large machines in bulk. Cream is the high-fat milk product separated from milk. The cream is processed and used to produce various products with varying names, such as “heavy cream” or “whipping cream.” Cream contains at least 18% milk fat. Some cream is dried and powdered and some is condensed by evaporation and canned.

Casein - The dominant protein (80%) in cow’s milk. Casein is vital to cheese making, and has a variety of uses in manufacturing as well.

Curd - The clumps of protein and other milk components that are formed during the cheese making process. Curds are pressed into blocks or barrels for proper aging and curing of the cheese.

Homogenization - A process applied to milk that results in fat globules being reduced in size to allow a smooth consistency. If milk isn’t homogenized, the cream separates and rises to the top of the container. When I was growing up, we would collect milk from the bulk tank then let it sit in our refrigerator until the cream rose to the top then skim the cream off before drinking it.

Processing Plant - A facility that pasteurizes, homogenizes and packages milk that comes directly from dairy farms. Once the milk leaves the processing plant, it is available to the public through a variety of channels, including grocery stores, schools and restaurants. Our milk goes to Middlefield Cheese (about 10 minutes from our farm) to be processed into Swiss cheese.

Pasteurization - Pasteurization is a simple, effective method to kill harmful pathogens through heat treatment without affecting the taste or nutritional value of milk. Since its introduction over a century ago, pasteurization has been recognized around the world as an essential tool for protecting public health. The process was named after its inventor, French scientist Louis Pasteur.

Whey - The watery part of milk that separates from the curds during the cheese-making process. The composition of whey varies considerably, depending on the milk source and the manufacturing process involved. Typically it is rich in lactose, minerals, vitamins and protein. Whey is used as an ingredient in a variety of human foods such as bread, crackers and fitness beverages. It can also used as an ingredient in animal feed.

Check out the Dairy Farming Today website to view the entire Dairy Dictionary and learn interesting facts about dairy farms, cows and milk.