The more I learn about the benefits or raw milk, and the denaturing of the proteins and loss of enzymes that occurs when milk is heat pasteurized, the more I find it difficult to advocate for anything other than raw milk. In just the past two months, I've had the opportunity to visit and tour two raw dairy farms (one in Tucson, AZ and another in Mineola, TX), and had the opportunity to meet the cows, the owners, and more importantly taste the milk and other dairy products made from the milk (yogurt, cheese, butter). There is absolutely no comparison in taste or healthfulness in consuming dairy products the way they have been consumed for over 5,000 years. I will always recommend raw milk over any type of pasteurized milk, even grass-fed organic milk pasteurized at low temps.
Having said that, I know some people don't have access to raw and still want to consume milk. So this is a case of choosing the lesser harm.
Here's a description of the different types of pasteurization. One and two are probably the least harm, while three and four are really horrible.
1. Low Temperature, Long Time (LTLT) Batch pasteurization (also called vat pasteurization). Back in the late 1800's when pasteurization was first introduced, all milk was pasteurized in this manner. A batch pasteurizer consists of a temperature-controlled, closed vat. The milk is pumped into the vat, heated slowly to a minimum temperature of 145° Fahrenheit, held at that temperature for a minimum of 30 minutes, cooled, and then pumped out of the vat. This method is relatively rare today because most dairies have advanced to newer pasteurization technologies that use higher temperatures. This original pasteurization technique is being used by Kalona Supernatural and MOO Milk and is marketed as a healthier milk because it uses the lowest temperature of any of the the other techniques.
Low temperature pasteurization destroys dangerous pathogens, but not all of the helpful probiotics, which is why this type of pasteurization is making a comeback among grass-fed daires. Unfortunately, the enzymes are still destroyed using low temperature pasteurization, so raw milk is still nutritionally superior. However, to its benefit, lower temperatures also preserve the fresh flavor of milk. The shelf life of this type of milk is a short 18 days before opening the carton.
With the advent of newer technologies, most commercial dairies now pasteurize milk through higher temperature methods, which include:
2. High Temperature/Short Time (HTST) pasteurization(flash pasteurization). To pasteurize larger quantities of milk in a more efficient manner, creameries began developing new processes as early as 1893. Today, HTST is the most common form of pasteurization in the milk industry. In an HTST processor, the milk flows continuously through a series of thin metal plates that are heated by hot water. The milk is heated to a minimum of 161° Fahrenheit for at least 15 seconds, and then rapidly cooled. This is what is being used by Organic Valley Grassmilk.
3. Ultra Pasteurized (UP) is heated to a minimum of 280° F for a minimum of two seconds and then cooled just as quickly.
4. Ultra High Temperature (UHT) is heated to temperatures between 275° and 300° F, using commercially sterile equipment to produce a shelf stable product that does not require refrigeration until it has been opened.
High heat pasteurization inactivates many of the flavor components in milk and adds its own cooked flavor. The process also affects whey proteins that contribute to the thick creaminess of dairy. In order to compensate, congealing agents like guar gum and carrageenan are added to ultra-pasteurized dairy to duplicate the original viscosity. This type of milk has a shelf life of 6 to 9 months before opening the carton!