Is Buttermilk Supposed to Smell Sour? – All You Need to Know

Cultured Buttermilk is a unique liquid that can be drunk straight from the bottle. But most people prefer to use it as an ingredient for baking cakes, cookies, frying food items, and making salads and smoothies. Although the name itself might make you feel like it is a combination of milk and butter, it isn’t. Today we will try to answer the question, “Is buttermilk supposed to smell sour?” Or does it smell like sour milk?

Traditionally, frozen Buttermilk is the leftover portion of milk that remains a residue once the butter has been churned from it. But at present, you can also make this ingredient at home using simple ingredients like milk and vinegar/lemon. But the burning question many people have in mind is whether it smells sour or has it gone wrong?

Keep reading this article, and you will know the answer!

Does Butter Milk Smell Sour or Not?

Ready-made or homemade Buttermilk is added in baking items to give it a sour and tangy taste and a super soft texture, but is it supposed to smell sour? Well, traditional Buttermilk does have a sour smell of its own. The reason behind this strange smell is the presence of good bacteria in it.

  • Traditional Butter Milk

When traditional Buttermilk is prepared, the whipping cream or heavy cream is separated from the milk through the process of fermentation. This process is initiated naturally with the help of lactic acid, which in turn gives rise to self-producing bacteria that process the milk into a creamy texture.

  • Store-Bought Butter Milk

The store-bought Buttermilk is made a bit differently from this. Hence, it shouldn’t smell too sour. This one is made by mixing harmless bacteria and some thickening agents to the milk, which help to ferment the lactose present. Due to this procedure, lactic acid is created, which precipitates the casein in the milk liquid.

This type of Buttermilk might have a bit of a tangy smell, but it shouldn’t be too strong. If you see a powerful sour odor coming from it, it will indicate that the milk has gone wrong.

How to Tell If You Have Spoiled Milk (butter milk) or Expired Buttermilk

Yes, bad Buttermilk or leftover buttermilk might have a slightly sour smell in general, but the scent can be strong if it has gone spoiled. It might be difficult for you to detect this if you are inexperienced with handling this ingredient. Therefore, we have listed down factors that will guide your senses and help you find out whether the Buttermilk is good.

Read below to know more:

  1. The Scent of the Butter Milk

As we have said before, the Buttermilk you will find in-store or even the traditional one tends to evoke a slightly sour smell due to bacteria’s actions. However, there is a tale-tell sign that could tell you whether the Buttermilk has gone wasted or not. By using your sense of smell, you can detect this. Usually, the more spoiled the milk is, the worse it will be its smell.

When the Buttermilk is fine, its sour smell won’t be hard on your nose. You will hardly be able to detect it. However, milk has a shelf life. Once it has adequately become spoiled, it will emit a pungent smell that will be too hard to ignore.

At the same time, one fact that you must remember is when you will newly open a carton of fresh milk or regular milk, you might smell a bout of sour scent as the air was trapped inside for long. This will go away after a short while, and it shouldn’t make you worry. This tangy smell will be bearable and not the same as the odor of spoiled Buttermilk.

  1. Appearance

You can detect whether the Buttermilk has gone wasted or not merely by the sense of your sight. The most obvious sign will be its appearance. When Buttermilk is wasted, it will have a discoloration that will be easy to notice.

And if the buttermilk has been stored way too long and has gone past its expiry date, you will see molds growing on its surface and lid. This happens because, with increased exposure to air, the milk’s bacteria get the chance to grow and produce mold.

Therefore, if you see any mold growing on the buttermilk, throw it right away. Drinking it might give you diarrhea or food poisoning.

  1. Consistency of the Milk

The consistency of the buttermilk is also an easy way to spot whether it is still in good shape or needs to be discarded. You can detect this by watching its flow, and if you are not sure, you can try touching it.

Usually, spoiled buttermilk spots a thick and clumpy texture. When you try to pour it into a jar, it will show big clots and won’t flow properly. It will instead remain stuck in the container. And once the milk has turned lumpy, it is a tale-tell sign that it won’t be salvaged.

However, it would be best if you remember that good quality buttermilk also has tiny lumps. But these clots are small and easy to break up with the help of a whisker. Besides, these also won’t obstruct the flow of the milk when you try to pour it.

But if the liquid sits in the carton and gets stuck while coming out, that is when you will know that the clumps are too big to come out, and the milk is spoiled.

  1. Butter Milk’s Taste

The usual taste of buttermilk is a bit tangy with a touch of creaminess. When you taste the milk, you can detect the rich buttery flavor of fermented milk along with a slightly sour smell that won’t be hard on your nose.

On the other hand, when the buttermilk is wasted, it will taste extremely sour and unpalatable. You can tell right away once you taste it that the milk has gone off, and you can’t swallow it down your throat without having nauseating feelings. As soon as you detect such an awful taste, discard the carton right away to avoid foodborne illnesses.

  1. Expiry Date

The most apparent sign that tells you whether something has gone off or not is the expiry date printed on its packaging. If all your senses fail you and you are unable to tell whether the buttermilk is good or not, you can simply look at its expiration date.

If you are too confused about whether the buttermilk smells too sour, or looks too thick, check its expiration date. If the current date is well past this date, you can know for sure that the milk is spoiled and you need to throw it away.


Buttermilk is an amazing ingredient to have in your pantry. It can enhance the taste of your baked goods or items and also help you cook up other amazing dishes. Although it is called buttermilk, it is not literally made with butter and is rather a fermented version of milk.

It usually bears a subtle tangy smell that is not very strong due to the action of milk fermentation. Fresh buttermilk won’t have a smell too sour that will irritate your nose. Therefore, it is important to always smell the milk before using it to know whether it has gone wasted or not.

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