How Are Dairy Products Processed?

Dairy products, specifically milk, can be prepared in many different ways. It can go through many different levels of pasteurization and homogenization which change how the milk tastes, and its nutritional properties.

Raw Milk

Raw milk is milk which does not undergo any type of treatment prior to human consumption. Before the process of pasteurization was discovered in 1864, all milk was consumed raw. This raw milk was often acquired from family owned cows (or goats, sheep, and other livestock), as the percentage of people living in rural, agriculturally concentrated areas was far larger then the number of people living in urban areas.

The consumption of raw milk is not commonly practiced in the United States currently, and raw milk is not always available in supermarkets. It can often be purchased directly from dairy farmers, however, and can be found in many European cheese products, such as the famous French Roquefort blue cheese.

Raw milk does not undergo the process of pasteurization and is therefore not always safe to consume. Pasteurization destroys potential bacteria which could be found in milk such as bovine tuberculosis, E. coli O157:H7, Listeria, and Salmonella. These bacteria are not common in raw milk and are present when infected cows give milk, or are caused by poor sanitary conditions in dairy farms.

The Department of Health and Human Services and the Center for Disease Control and Prevention recommend that people do not consume raw milk or raw milk products.

Pasteurization

During pasteurization milk is heated to a specific temperature and kept at that high temperature for a certain amount of time, and then immediately cooled. This process does not kill all the micro-organisms in the milk, but instead slows the microbial growth of organisms in the milk. This process was initially used in China and Japan to preserve wine. Modern pasteurization was created by Louis Pasteur, a French chemist and microbiologist.

Ultra Pasteurized Milk

Ultra pasteurized milk is heated to 280 degrees Fahrenheit for a period of at least two seconds. This extremely high temperature kills virtually all of the micro-organisms found in milk. The process of ultra pasteurization makes milk last much longer then regularly pasteurized milk. Ultra pasteurized milk can last an average of 30-90 days when refrigerated.

Homogenization

The Encyclopædia Britannica defines homogenization as the "process of reducing a substance, such as the fat globules in milk, to extremely small particles and distributing it uniformly throughout a fluid, such as milk." Homogenization is used to mix the milk from different cows or from different dairy farms to produce a consistent product. Homogenization is also used to prevent the separation of cream from milk. Homogenization is essential when creating various levels of fat in milk, e.g. fat free milk, two percent milk, and whole milk.