Posted by: Mahdi Ebrahimi | June 8, 2008

Why does organic milk last so much longer than regular milk?

f you’ve ever shopped for milk, you’ve no doubt noticed what our questioner has: While regular milk expires within about a week or sooner, organic milk lasts much longer—as long as a month.

So what is it about organic milk that makes it stay fresh so long?

Actually, it turns out that it has nothing to do with the milk being organic. All “organic” means is that the farm the milk comes from does not use antibiotics to fight infections in cows or hormones to stimulate more milk production.

Organic milk lasts longer because producers use a different process to preserve it. According to the Northeast Organic Dairy Producers Alliance, the milk needs to stay fresh longer because organic products often have to travel farther to reach store shelves since its not produced throughout the country.

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.

Compare that to pasteurization, the standard preservation process. 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: Pasteurization doesn’t kill all bacteria in the milk, just enough so that you don’t get a disease with your milk mustache. UHT, on the other hand, kills everything.

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 doesn’t need to be refrigerated and can sit on the shelf for up to six months.

Regular milk can undergo UHT, too. The process is used for the room-temperature Parmalat milk found outside the refrigerator case and for most milk sold in Europe.

So why isn’t all milk produced using UHT?

One reason is that UHT-treated milk tastes different. UHT sweetens the flavor of milk by burning some of its sugars (caramelization). A lot of Americans find this offensive—just as they are leery of buying nonrefrigerated milk. Europeans, however, don’t seem to mind.

UHT also destroys some of the milk’s vitamin content—not a significant amount—and affects some proteins, making it unusable for cheese.

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.

source: sciam



  1. We are Organic Living TV ( a national PBS and syndicated television series that reaches over 34 million homes each week.

    Here is a segment we filmed last weekend at the ‘Stop the Spray’ benefit concert:

    Not sure if you were aware of the plan to spray plastic nano-spheres filled with fertility disrupting chemicals all over the bay area (and other parts of the U.S.), in a futile attempt to eradicate a little brown apple moth. The spraying that occurred a few months ago in Santa Cruz and Monterey caused 600 people (mostly kids) to develop chronic asthma – where previously they were perfectly healthy!

    Anyway, please feel free to blog about this post and/or embed the segment into your site and share it with your audience.

    Best regards!

  2. If you are looking to purchase organic milk for benefits other than longer shelf life, you should be conscious of what milk you buy. Certain big brand-names have been investigated by the USDA for not being as organic as they should be (i.e. milking previously conventional cows or not confining cows to feedlots). As far as reliable organic milks go, Organic Valley and Natural by Nature are good choices.

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