Does Buttermilk Go Bad?

Like most dairy products, we buy buttermilk, put it in the refrigerator, and use it as we see fit. This can make the carton of buttermilk last for a few days or maybe a week. Sometimes, we may forget that we have the buttermilk sitting in the refrigerator, so it might go past that date printed on the carton that tells you when the buttermilk expires. We may grab the carton and smell the buttermilk, while wondering if the buttermilk has gone bad.

Buttermilk does go bad after a period of time. It tends to go bad after the date printed on the carton of buttermilk has passed. In some cases, buttermilk can still stay good after this date, but it is important to know how to tell if the buttermilk has spoiled, so you know when it is no longer safe to use the buttermilk.

Continue reading to learn more about how long buttermilk can last. Also, continue reading to learn more about how you can tell if your buttermilk has expired.

Does Buttermilk Expire?

Buttermilk does expire. This goes for all dairy products. After a period of time, the ingredients in the buttermilk will break down.

The manufacturers of the buttermilk will often put a sell-by date on the carton of the product. Many of us use this date to determine which carton of buttermilk, or other dairy product, that we purchase, since we want to buy the one that will last for the longest amount of time rather than the one that will spoil the fastest.

While this date is what sellers use to determine if the product can remain on the shelf or if the product needs to be thrown away, this date does not exactly define when the product will spoil. 

How Long Does Buttermilk Last?

Like all dairy products, a carton of buttermilk will have a “best by” or “sell by” date printed somewhere on the carton. Many believe that if a product goes beyond this date that it should be thrown out, but this is not the case.

The “sell by” date is meant to inform the seller on how long they can keep this product on their shelves. This does not necessarily mean that the product has gone bad. An expiration date, on the other hand, is what tells you when the product has gone bad. Buttermilk typically has a shelf life of two weeks.

After these two weeks, the buttermilk can start to go bad. This may not happen immediately, so it is important that you know what signs to look for to determine if your buttermilk has gone bad.

How Can You Tell If Buttermilk is Bad?

Since the “sell by” date is not a good indicator of whether or not buttermilk is still good to use, it is important that you know different ways to tell if the buttermilk has gone bad. Similar to other foods, certain aspects of buttermilk will change when it begins to spoil. From smell to taste to how the buttermilk looks, each of these can be a strong indicator of whether you can still use your buttermilk or whether you should throw it away.

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It is also important to note that expired buttermilk may not show all the signs that it is spoiled. The buttermilk may still look fine, but the smell and taste can be off. 


Smelling the buttermilk can be one of the simplest ways to tell if the buttermilk has gone bad. Buttermilk has a smell that is somewhat tangier than milk or other dairy products. If the buttermilk is still good, this smell is still quite pleasant despite being tangy.

Once your buttermilk has gone bad, the smell becomes much stronger and more sour. This sour smell is often described as pungent, terrible, and gross. Since the smell becomes stronger, just opening the carton can reveal if the buttermilk has expired. You may, however, need to pour a glass of the buttermilk in order to determine if the smell is that bad.


While buttermilk does have a tangy taste, the taste of buttermilk is still pleasant and does not make you want to avoid the buttermilk. Tasting the buttermilk is the second best method that you can use to tell if the buttermilk has expired or not.

The taste of buttermilk is one that is tangy, buttery, and creamy. However, the taste will shift to one that is sour once it has expired. Buttermilk that is still good should not have a sour taste. If anything about the taste changes, it is safe to assume that the buttermilk has expired and should be thrown away.


Another great way to tell if your buttermilk has expired is by looking at the appearance of the buttermilk. Buttermilk has a creamy and buttery look, but the coloration is similar to the coloration of milk, but there is a slight yellow tint to the buttermilk.

When buttermilk spoils, it will become discolored. This discoloration can be easy to spot if you drink or use buttermilk regularly. This discoloration is a strong sign that the buttermilk should be thrown out.


Buttermilk has a smooth and creamy texture. When you pour a glass of buttermilk, you may notice that the milk has some lumps. These lumps should go away by stirring the milk. If these lumps do not go away, this can be a sign that the buttermilk has expired.

When buttermilk expires, the texture becomes one that is much thicker and chunky. This is similar to how regular milk becomes clumpy when it expires. The milk will also no longer be easy to pour. If you notice that your buttermilk has changed from a creamy and smooth texture to a texture that is chunky and thick, it should be thrown away.

Expiration Date

The expiration date can also be a good indicator for when buttermilk has spoiled. While you do not want to go by the “sell by” or “best by” dates, you should go by the expiration date that is on the carton if there is one.

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While buttermilk can last for a week or two after this date, this date can be a good indicator that the buttermilk will soon spoil. 


If you pour a glass of buttermilk and notice that it has mold growing, it is best to throw the buttermilk away. This is a sure sign that the buttermilk has spoiled. This mold is the result of bacterial growth in the buttermilk.

It is best to throw the buttermilk away if you see mold as using the buttermilk can result in you contracting a foodborne illness. This mold can look like fuzzy patches that are pink or gray in color. Mold can often be the result of leaving the buttermilk in the refrigerator for a long time.

Is It Okay to Use Expired Buttermilk?

As long as none of the above signs are present, the buttermilk can still be safe to use even if it has passed its expiration date. You can use expired buttermilk in dishes that involve the buttermilk being cooked, as long as there are no troubling signs. This can cause any bacteria that has grown in the buttermilk to be killed.

If your buttermilk has passed its date of expiration but shows no signs of spoilage, you can freeze this buttermilk in order to make it last a little longer. It is important, however, to note that, once the buttermilk has been frozen, it should not be refrozen as this can cause changes in the texture of the buttermilk.

How Do You Prolong the Shelf Life of Buttermilk?

If not stored properly, buttermilk will not last for its intended shelf life. You do not want to keep your buttermilk out at room temperature. The best place to store your buttermilk is in the refrigerator where it can be kept cool. You also want to leave the carton unopened if you do not plan on using the buttermilk in the very near future. An unopened carton of buttermilk will stay fresh longer than an opened carton.

You also want to never drink directly from the carton as this can expose the buttermilk to more bacteria which could make the buttermilk spoil more quickly. If you are not planning on using the buttermilk soon, you can also freeze the buttermilk as this will help to extend its shelf life.

Final Thoughts

Buttermilk can be a nice beverage to drink as well as an ingredient in some recipes you may cook. You may buy buttermilk from the store and leave it in the refrigerator for a certain period of time. You want to ensure that you do not leave the buttermilk to sit for too long as it does spoil.

It is always best to check your buttermilk for signs of spoilage, like clumps or mold, before using the buttermilk. If any of these signs are present, it is best to throw the buttermilk away as using it can make you sick.