When making comparisons at the grocery store between a gallon of conventional milk and a container of organic milk, you might notice that the “best by” dates are vastly different.
Why does organic milk last longer? Is there something added to it that prevents it from going bad, something in regular milk that makes it sour more quickly or does it have something to do with shipping?
Comparing organic and regular milk (and looking at shelf-stable milk) can shed light on these different types of milk and help you decide which is best for your family.
What is Organic milk?
The difference between organic milk and conventional milk is primarily in the way dairy farmers raise, feed and treat the cows that produce the milk. In the U.S., milk can only be labeled with the U.S. Department of Agriculture Organic seal if the farm where it is produced complies with this set of regulations:
Why Does Organic Milk Last Longer?
There is one other difference between regular and organic milk, and this distinction answers the question, “Why does organic milk last longer?” This difference is in the way that milk is pasteurised.
According to the Dairy Alliance, dairies pasteurise conventional milk using a standard method, heating the milk to approximately 71.1C for at least 15 seconds. However, they use ultra-high temperature (UHT) processing for organic milk, heating the milk to 137.8 C for 2 to 5 seconds. This method kills more bacteria, resulting in a longer shelf life.
Part of the reason organic dairies use this method is that antibiotics are not used in the production of organic milk.
(Addition by Full of Soil and Sun: Antiobiotics reduce the number of good bacteria and therefore lower number of bacteria will be reduced and in turn lower temperatures will be used. But antiobiotics are left in the conventional milk and they are considered as contaminants of the milk which is bad for our health)
But the other purpose is to provide more time to distribute the milk to retailers since there are fewer organic dairy farms across the U.S. By using UHT processing, producers can ensure that the products will reach store shelves without spoiling.
The downside of UHT processing is that it can affect the taste and consistency of the milk. For example, the milk might have a “cooked” flavor that is less rich and full-bodied than conventional milk is. And because the process burns some of the natural sugars in the milk, it can taste sweeter, which some milk drinkers find off-putting.
According to Consumer Reports, ultra-pasteurised milk has a shelf life of 40 to 60 days unopened, while conventionally pasteurised milk has a 15- to 17-day shelf life. That being said, consumers should drink or discard all milk within seven days of opening, regardless of the “best buy” date, according to the USDA. You can also freeze milk for about three months and thaw it in the refrigerator, but you should also consume it within a week.