What Does Pasteurization of Milk Mean?

Before the invention of pasteurization, people often dealt with food spoilage. Milk constituted a nutritional addition to the family fare, and parents often fed their infants and small children cow's milk. Children died unexpectedly because the cow's milk they drank carried many types of harmful, microscopic organisms. With the dawn of pasteurization, people could safely consume milk, eggs, beer and other foods and beverages while keeping the taste and nutritional qualities of these food items intact.

History

• Louis Pasteur was a French chemist who dedicated his life to improving human health.

  Louis Pasteur spent his life fighting disease. At first, he turned his attention to preventing food from spoiling. He discovered that organisms impossible to see with the naked eye, such as bacteria, caused human food and drink to spoil. Pasteur found that microorganisms not only caused food spoilage, they also endangered human health.

  Pasteur was not the first person to contemplate the idea of milk preservation. Historical records indicate that 40 years before Pasteur's idea, William Dewes suggested heating baby's milk before feeding. In 1853, Gail Borden received a patent for heating, thickening and preserving milk using sugar. After Pasteur's discovery, Soxhlet performed the new technique on baby's milk.

Significance

• The process of milking allows bacteria from cow waste to contaminate the milk.

  Untreated milk products contain a variety of microorganisms, that if left to multiply, could cause disease in humans. Pathogens carried by raw milk can cause diseases such as diphtheria, tuberculosis and food poisoning. Contamination occurs during the milking process when cow feces contaminate the milk. Pasteurization destroys harmful organisms and delays the process of fermentation, which causes milk to sour quickly. The process of pasteurization does not purge slow-growing organisms or eliminate spore production, which protects organisms such as bacteria during adverse conditions. Even with pasteurization, unsafe handling techniques following pasteurization may lead to additional contamination.

The Process

• Dairy farmers can pasteurize milk under several conditions. Heating milk to 165 degrees Fahrenheit for 15 seconds essentially kills the detrimental organisms while retaining the fresh milk taste. Other techniques ensure all microorganisms die by heating the milk to even higher temperatures, but the flavor suffers. Ultra-high temperature pasteurization offers a compromise, eradicating all harmful organisms while minimizing any flavor changes. After pasteurization, the milk needs to be refrigerated in closed containers to lower its internal temperature to 40 degrees F.

Home Pasteurization Techniques

• A double boiler can be used to pasteurize small amounts of milk at home.

  Milk pasteurization can be performed at home. Using a double boiler, you heat the milk to 165 degrees F for 15 seconds while continuously stirring. You then remove the top portion of the double boiler and sit it in cold water while stirring the milk, cooling it to 145 degrees F. By adding ice cubes to the water bath, lower the temperature of the milk to about 40 degrees F. At this temperature, you can transfer the milk to closed containers and refrigerate at 40 degrees F or lower. You should not use microwaves for home pasteurization because they do not heat the milk uniformly.

Taste and Nutritional Concerns

• Consumers fault pasteurization techniques for creating a burnt taste in milk because the application of high heat affects the taste and vitamin content of the milk. Oregon State University's Department of Food Sciences and Technology has discovered a type of pasteurization that uses high pressure combined with low pasteurization temperatures to maintain the original taste of milk. Even with the lower temperatures, the process still kills pathogens and organisms that initiate the fermentation process. With conventional pasteurization, milk is viable for about two weeks; with the newly discovered process, milk can last for a month and a half.