How Long Can Unopened Milk Stay Out of the Fridge?

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Drinking spoiled milk is probably one of the worst experiences I’ve ever had. That’s why I decided to find out exactly how long unopened milk can stay out of the fridge before it goes sour.

And after doing some research, I came up to some surprising conclusions regarding its shelf life.

It turned out that in some cases unopened milk could last for way more than what’s recommended by the FDA.

Keep reading to get the full run-down on how long unopened milk can last.

How long can a bottle of unopened milk stay out of the fridge?

The amount of time you can leave unopened milk sit out, mostly depends on the way it is pasteurized.

Pasteurization is a process in which milk gets heated to a certain temperature, then quickly gets cooled down.

This process is used to destroy harmful bacteria and make milk safe to drink.

There are two methods of pasteurization: High Temperature Short Time also known as HTST and Ultra High Temperature or UHT.

Milk that’s pasteurized through HTST pasteurization contains small amounts of bacteria so it shouldn’t be left unrefrigerated for more than 2 hours even if it’s unopened. UHT milk, on the other hand, doesn’t contain any pathogens so it can last for up to 9 months as long as it’s unsealed.

Having said that, after a bottle of UHT milk is opened, it needs to be stored in the fridge after it passes the 2 hour mark.

That’s because once the carton gets unsealed, all of the nasty bacteria that were kept at bay have a chance to creep in.

And if they do, they can multiply at rapid rates and cause the milk to spoil.

To make things worse, these tiny troublemakers will need no more than an hour to spoil your day if the ambient temperature is higher than 90°F / 32°C.

Anyways, when stored in the fridge after opening, milk will last between 4 – 7 days regardless if it’s UHT or not.

If you intend to keep UHT milk at room temperature, then you’ll need to store it in a cool, dark place.

The lack of sunlight and low temperatures will minimize the risk of spoilage and increase its shelf life.

These guidelines also apply to almond milk and other plant based alternatives.

Can you drink milk past its sell by date?

Many people tend to throw out perfectly good milk because they misinterpret the meaning of sell by dates.

Date labels such as “sell by”, “best if used by”, “use by” and “best by” are used to determine the last day at which milk is of peak quality.

Even though this information can be quite useful for dairy products with everchanging flavor qualities, it doesn’t tell us if milk has actually expired or not.

In fact, regular whole milk will still be safe to drink for an entire week after its sell by date, provided it’s refrigerated.

This timespan increases to 10 days for unopened non fat milk and between 2 to 4 weeks for unopened UHT milk.

If you’re worried that your milk has gone bad, you should inspect its smell and texture.

One of the tell-tale signs that points to spoiled milk is the presence of a sharp, vinegary odor.

This happens because the lactic bacteria in the milk begin to convert milk sugar into lactic acid.

Even though this is a sought after effect for buttermilk and yogurt, it’s something you don’t want in fresh milk.

In terms of texture, you’ll probably notice that the milk will have begun to curdle at the same time you notice the change in smell.

This is a direct effect of the increased acidity which causes proteins to clump together and separate from the liquid.

How to properly store milk

The best way to store milk is to keep it refrigerated at a constant temperature of 37°F to 40°F (2.8°C to 4.4°C).

You should refrain from placing your milk at the refrigerator door since the temperature there fluctuates more than the inside of the fridge.

Another thing you should keep in mind is to keep milk in its original packaging.

Storing milk into a glass bottle or a jug might be appealing, but it also increases the chance of microbial growth and spoilage.

Lastly, you should wipe the cap with a clean cloth or a paper towel anytime you open your carton of milk.

This will keep the buildup of residue at a minimum and prevent the growth of bacteria.

an opened fridge with a bottle of milk being stored deep in the back

by scottzee

Wrapping up

Even though it’s a highly perishable product, unopened milk can stay unrefrigerated for a long period of time when it’s pasteurized at an ultra high temperature.

Regular milk, however, isn’t as long lasting and should be taken with caution if it’s left for more than 2 hours at room temperature.

So if you’ve accidentally forgotten a carton of milk in your car overnight, it would be best to toss it.

Feel free to post any questions or thoughts you may have down in the comments.

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