8 Things You Didn’t Know About Buying and Storing Milk

By Janet Rausa Fuller, Epicurious


Photo: Richard Rutledge

There’s so much more to a gallon these days. Ultra-pasteurized, rBST-free, omega-3 fortified… and we’re just talking milk from cows.

We asked Jane Andrews, manager of nutrition and product labeling for Wegmans, to help us sort through the cartons in the dairy aisle. The supermarket chain moves a lot of milk, much of it a house brand produced by a cooperative of family farms in upstate New York and Pennsylvania.

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Milk in opaque containers is more ideal than glass, as exposure to light will break down some of the vitamins in milk, Andrews said.

Choose the carton with the latest “use by” or “best by” date stamped on it, but don’t feel bound by that date. It indicates peak freshness, but not necessarily the starting point for spoilage.

That said, don’t buy more milk than you need, and keep the milk cold. No matter what the date on the carton reads, once opened, it’ll last about a week in your fridge, Andrews said.


Most milk sold in stores is pasteurized and homogenized.

Homogenization is a mechanical process that breaks down fat molecules so the milk stays, well, milky smooth. Non-homogenized milk separates into layers. You’ll see it labeled as “cream top,” or something similar.

In pasteurization, milk is quickly heated and then cooled to kill harmful bacteria such as E. coli and salmonella. Ultra-pasteurization takes that up a notch to a much higher temperature, resulting in an even longer shelf life, up to six months for an unopened, shelf-stable carton, Andrews said. Some say ultra-pasteurized milk tastes a bit different, “more cooked,” she said.


Raw milk is not pasteurized—and highly controversial. Advocates say it’s more nutritious. The USDA, FDA and CDC say it can carry potentially deadly bacteria.

Depending on where you live, raw milk might be hard to find. It’s limited to on-the-farm sales in some states, and is illegal to sell in 19 states.


Whole milk is 87 percent water and 13 percent other stuff: fat, protein, carbohydrates, vitamins and minerals. High-speed centrifuges spin off the fat to produce lower fat varieties: reduced fat (2 percent milkfat), lowfat (1 percent milkfat) and skim (nonfat).


Almost all milk is fortified with Vitamin D, which helps with calcium absorption. Federal law requires that reduced fat, low fat and skim milk to be fortified with Vitamin A, which is lost when the fat is spun off.

You’ll even see milk with added protein, fiber and omega-3 fatty acids, though in the latter case, these aren’t the same omega-3s that are found in fish, Andrews said. You’d have to drink a lot of milk to get the equivalent amount in, say, a serving of salmon.


Organic milk, as defined by the USDA, is from cows raised on organic, pesticide-free feed, without growth hormones or antibiotics. Federal rules also require that the cows spend at least four months on grass and that 30 percent of their diet is from grazing on pasture.

Speaking of omega-3s, some research suggests organic milk has more of them than conventional milk. Still, if it’s omega-3s you’re after, you’re better off eating fish, Andrews said.

“Don’t go with organic or grass-fed because you think you’re going to get more omega-3s. It’s inconsequential. Go for it because you believe in [organic food], or you like the taste,” she said.

Whatever your reasons, you’ll pay a premium for organic — $1.86 more on average for a half-gallon, according to the USDA.


Cows produce a hormone called bovine somatotropin, or BST, that helps them make milk. A synthetic version called rBST (also known as rBGH) boosts milk production further. The drug is FDA-approved but not without controversy. It’s banned in Canada, Europe and several other countries, and critics have questioned its health effects on people.

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But Andrews said the trend has moved the other way, with more milk produced without rBST. To steer clear of rBST, buy organic or look for labeling that clearly says the milk is from cows not treated with rBST.


Lactose-free milk has an added enzyme called lactase, which breaks down the sugar in milk that some people have a hard time digesting. It tastes sweeter than regular milk and will last as long as regular milk in the fridge.

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