During a trip to London the second week of April this year to visit my youngest daughter and her husband who was studying there for one semester, I used British milk on my fruit and fiber cereal. This milk capable of storage in a cupboard had a "best used by" date of Aug. 28, 2012, a five-month shelf life. I was astonished by the lengthy shelf life and exclaimed, "Holy cow, how can that be?"
After returning home, I went on a mission to learn how this British milk stayed preserved. Our milk cartons in the United States state "pasteurized milk," which I believe most people realize means milk is heated to kill germs so that it stays fresh for two weeks, but requires refrigeration even before opening unlike the British milk. Safe, healthy, bacteria-free milk and juices have been available for more than 100 years since pasteurization became routine. Before this time, infant mortality of 10 percent was attributed to illness from consuming raw, unpasteurized milk. The world owes gratitude to the French scientist Louis Pasteur, who more than 130 years ago discovered that organisms like bacteria caused beer and wine to spoil. By heating the wine and beer, bacteria were killed and spoilage prevented. This heating process became known as pasteurization.
During a telephone interview with the person responsible for pasteurization procedures at large dairy bottling organization in Buffalo, I learned about the process. Raw milk directly from a cow contains germs (bacteria) present on the udders which will cause spoilage of the milk and illness in people; therefore, raw milk is heated to 161 degrees Fahrenheit (F) for 30 seconds. This kills most bacteria, allowing a refrigerated "best used by" date of 17 days.
This carton of British milk is ultra heat treated so it can be stored in a cupboard unrefrigerated for five months or more.
Photo by Robert M. Ungerer
Ultrapasteurized dairy products, "half and half" and cream, are heated to 282 degrees for two seconds in a large pressure cooker. The pressure cooker produces temperatures above boiling (212 degrees F) that are needed to kill bacteria and spores.
The British milk that I experienced is heated to the same 282 degrees for two seconds, known as "ultra heat treated" (UHT), but is packaged by using sterilized machinery and a sterilized single sheet of laminated paper shaped into a carton. The milk is considered aseptic, meaning all organisms have been killed, so an extended unrefrigerated shelf life of up to nine months is possible. North Americans did not accept ultra heat treated milk because it is not refrigerated, although the United States military uses UHT milk because it can be transported abroad and stored near a battlefield without refrigeration. The UHT process is used for fruit juices sold in grocery stores. At least one national fast food chain uses UHT milk in its ice cream desserts. Nutrition remains the same as in regular pasteurized milk, although folate levels are reduced by the higher temperature. Heating milk above boiling temperature creates a cooked flavor, which some people enjoy.
Pasteur's other work included developing a vaccine for rabies in 1885 after a trial on a young boy, Joseph Meister. In 1867, Joseph Lister, a Scottish surgeon, capitalized on Pasteur's discovery that disease is caused by "germs" by sterilizing his surgical instruments and his own hands with carbolic acid before he operated. Death by post-operative infection dropped dramatically from 50 percent to 3 percent.
Pasteur experienced triumphs and tragedy in his life. He and his wife, Marie, had five children, four daughters and one son. Three daughters died at ages 2, 9 and 12, two from typhoid fever well before vaccinations were developed. During Pasteur's lifetime, he was honored by the French government as a hero. One Pasteur biographer, Gerald Geison, noted Pasteur kept meticulous laboratory records, made astounding discoveries - occasionally by accident - all of which revolutionized how future scientists created immunity with vaccinations.
Today mankind can savor the flavor of fruit juices from around the world as well as enjoy delicious dairy products like yogurt, ice cream, and milk because pasteurization makes them safe to consume thanks to the scientific discoveries of Louis Pasteur more than 100 years ago.