Do you toss out milk on its sell-by date even though it would be good for an additional five to seven days? Do you take a deep sniff of the container’s opening before pouring, just in case it decided to spoil early? If so, researchers at Purdue University may have a solution.
According to a study published in SpringerPlus, a simple addition to the standard pasteurization process—which heats milk to kill bacteria before packaging—can eliminate even more contaminants. Using a method called low-temperature, short-time (LTST) processing, milk batches are treated normally and then heated to just 10°C for less than a second. That kills 99 percent of the residual germs left behind after the first round of pathogen-killing has occurred. With fewer bacteria, the milk can remain fresh for longer periods of time—up to five to seven weeks past the standard expiration date.
Because it uses low heat, this technique is different from the existing method for creating milk with a long shelf life: ultra-high temperature (UHT) processing, in which milk is heated to 138°C for 2–4 seconds. Another difference? Unlike UHT [PDF], this method doesn't appear to alter the taste.
This does not mean, however, that you can unseal a container of milk and then expect to enjoy it for months at a stretch. For one thing, a gallon wouldn’t last that long. More importantly, the freshness is dependent on a closed container. Once it’s exposed to air, Purdue’s patented process will still result in the same milk, which has about a week before it goes bad.
Researchers might test the LTST process to see if it might be able to replace—not just support—standard pasteurization. There’s no word on when the technique might be adopted by manufacturers, but since the study was funded in part by the U.S. Department of Agriculture, it probably won’t be long before anti-aging milk starts appearing on shelves.