According to the American Dietetic Association's Complete Food and Nutrition Guide, the answer to this question results from the process of flash heating milk, or pasteurizing it, a requirement for dairy farmers before selling their dairy.
- Scientific American (2008).
The process that gives the milk a longer shelf life is called ultrahigh temperature (UHT) processing or treatment, in which milk is heated to 280 degrees Fahrenheit (138 degrees Celsius) for two to four seconds, killing any bacteria in it.
The Scientific American article on this subject confirms that "Organic" simply refers to the fact that no antibiotics or growth hormones are used in the products, so raw milk, for example can be both organic and unpasteurized.
The difference between ultrahigh temperature (UHT) and pasteurization, which is the most popular and standard preservation process is explained like this: There are two types of pasteurization: "low temperature, long time," in which milk is heated to 145 degrees F (63 degrees C) for at least 30 minutes*, or the more common "high temperature, short time," in which milk is heated to roughly 160 degrees F (71 degrees C) for at least 15 seconds.
The different temperatures hint at why UHT-treated milk lasts longer: Public health officials preach that pasteurization does not kill all bacteria in the milk; just enough so people do not get a disease with their milk mustache. UHT, on the other hand, undeniably, kills everything. Ask any green-die-hard-earthy-farmer and he will tell you the exact opposite. They seem to always drink the milk straight from the source, just like the old days. Pasteurization actually "kills" food and makes it less nutritious. In fact, pasteurizing dairy and dairy products do not kill all harmful micro-organisms, destroys active enzymes in foods, diminishes the vitamin content of food, denatures fragile milk proteins and kills beneficial bacteria. Dr. Weston A. Price spent his life trying to link dietary habits of the modern man to disease and concluded that pasteurized milk is largely to blame for a large assortment of health problems including allergies, increased tooth decay, colic in infants, growth problems in children, osteoporosis, arthritis, heart disease and cancer.
On a side not about "organic dairy and other produce." According to the Environmental Health News (2009), there have been many reports that low grade antibiotics and regular non-organic feed are still being used to keep milk producing animals resistant to disease and productive, even when labeled “organic” by the USDA. Even the nation’s largest dairy corporation, Dean Foods, the maker of Horizon Milk, added non organic synthetic oils to its milk and continues to label their product “organic” (Washington Post, 2010). I have had the opportunity to interview a few organic farmers and they claim to agree that not everything labeled 'organic' is exactly 100% from start to finish organically produced. "As long as we show that we buy organic feed once in the whole year, we are covered." Sadly, less than only 2% of all agricultural farms and factories are every audited or inspected by the government. I suggest people to grow their own food using hydroponics or vertical farming which uses no soil, and less land. For more information or to buy your own hydroponic, contact Dr.Nancy@truthNhealth.com.
Back to the discussion on hand. Typically, how long does pasteurized milk last? Retailers typically give pasteurized milk an expiration date of four to six days. Ahead of that, however, was up to six days of processing and shipping, so total shelf life after pasteurization is probably up to two weeks. Milk that undergoes UHT does not need to be refrigerated and can sit on the shelf for up to six months. UHT also destroys much of the milk’s vitamin content, just like microwaving milk does as well. It also affects some proteins, making it unusable for cheese. And UHT-treated milk tastes different. "The UHT process sweetens the flavor of milk by burning some of its sugars (caramelization) and many Americans find this offensive—just as they are leery of buying non-refrigerated milk. Europeans and Asians, however, drink this type of milk more regularly" -Scientific American (2008).
There are, of course, lots of reasons people buy organic milk. But if it's the long shelf life you're after, I would recommend you buy nonorganic UHT milk and avoid being charged double.
Unfortunately, pasteurization destroys some enzymes as well as possibly-beneficial microbes, though lower-temperature pasteurization may be effective and less destructive. Some people believe, therefore, that despite the safety it offers, pasteurized milk is an inferior product to raw milk.
Advocates of unpasteurized milk or raw food activists do argue that if milk is obtained from humanely raised cows that are grass fed and handled hygienically, then there is little problem with disease. However, the FDA and CDC warn that such milk and milk products have no protection against contamination and are aggressively shutting down raw diary factories and manufactories that resist pasteurizing their products.
I really liked F. Pottenger’s comment on clinical and experimental evidence of harmful bacterial growth factors in raw milk in 1937. “Let us have closer cooperation between raw-milk producers and public-health officials so that the growth-producing factors of raw milk can be studied. We cannot afford to pasteurize milk if it is found that pasteurization diminishes the potency of the growth-promoting factors that determine the skeletal development of our children. We cannot afford to lessen the resistance of our children to respiratory infection, asthma, bronchitis and the common cold when factors preventing them are present in greater amounts in properly clean raw milk than in pasteurized milk." It is amazing how the battle between raw-milk producers and the public health (government) officials is still going strong today.
Resources: ScientificAmerican.com (June 6, 2008 by Craig Baumrucker), OrganicMilkReview.com, KitchenScoop.com, GreenLiving.About.com