How To Tell If Buttermilk Is Bad

Buttermilk is a versatile ingredient that adds a tangy flavor and creamy texture to various dishes. It’s a popular choice in baking, marinating, and even some beverages. Unfortunately, similar to other dairy products, buttermilk can go bad if not used within a certain timeframe or if it’s not stored properly. Knowing how to determine whether or not your buttermilk has spoiled is essential to ensuring the quality and safety of your recipes.

Just like any other perishable food item, the freshness of buttermilk is contingent on its storage method, and learning the signs of spoilage can protect you from consuming a product that could be harmful to your health. In this article, we will discuss tips and tricks to identify whether your buttermilk has gone bad, focusing on factors such as its appearance, smell, and taste. With a better understanding of these indicators, you will be well-equipped to confidently assess the quality of your buttermilk before incorporating it into your favorite dishes.

Signs of Spoilage


One of the first signs of spoilage in buttermilk is a change in color. Fresh buttermilk should have a pale, creamy white hue. If you notice any yellowing or darkening, it’s a sign that the buttermilk has started to spoil due to the growth of bacteria.


Mold growth is a clear indication that your buttermilk has gone bad. If you see any spots of mold on the surface or within the liquid itself, it’s best to discard the entire container. Mold can produce harmful toxins, and consuming moldy buttermilk can lead to food poisoning.

Texture and Consistency

The texture of fresh buttermilk should be smooth and slightly thick, with small lumps resulting from the presence of milk solids. If the buttermilk has turned excessively thick, chunky, or slimy, it’s a sign of spoilage. Separation of liquids into distinct layers may also indicate that the buttermilk has gone bad.

To check for spoilage, pay attention to these changes in buttermilk:

Fresh ButtermilkSpoiled Buttermilk
Pale, creamy whiteYellowing or darkening
Smooth, slightly thickExcessively thick, chunky, or slimy
Small lumps (milk solids)Large, unusual lumps

Smell and Taste

Fresh buttermilk has a tangy, slightly sour smell and taste that is normal due to the presence of lactic acid bacteria. However, if the buttermilk develops a strong, rotten, or foul odor, it’s a sign that it has spoiled. Additionally, if the taste is overly sour or off-putting, it’s best to discard the buttermilk.

Remember, always trust your senses when determining if your buttermilk has gone bad. If you’re unsure, it’s best to err on the side of caution and avoid consuming it.

Determining Buttermilk’s Shelf Life

Opened vs Unopened

The shelf life of buttermilk depends on whether it is opened or unopened. Unopened store-bought buttermilk can last up to 2 weeks past its expiration date when kept in the refrigerator. Once opened, it should be consumed within 7-10 days.

Refrigerated vs Room Temperature

Buttermilk should always be stored in the refrigerator in an airtight container. At room temperature, it will spoil quickly, and it’s not safe to drink. Here’s a comparison of the shelf life of buttermilk when stored properly:

Storage MethodShelf Life
Unopened2 weeks past expiration
Opened7-10 days

Expiration Date

The expiration date on store-bought buttermilk is a general guideline. It could last longer if properly stored in a refrigerator. Make sure to check the smell, taste, and appearance of the buttermilk to determine its freshness. If it smells sour, has mold, or appears to be curdled, it should be discarded.

In summary, the key factors to consider when determining buttermilk’s shelf life are whether it’s opened or unopened, stored at a refrigerator temperature, and its expiration date. Make sure to store buttermilk properly in an airtight container and check its freshness before using it.

Safety Considerations

Foodborne Illness

Buttermilk is a dairy product that can become unsafe to consume if not stored at the correct temperature or if it has become contaminated with harmful bacteria. It is essential to keep buttermilk refrigerated at temperatures below 40°F (4°C) to prevent bacterial growth.

It is worth noting that pasteurized buttermilk has a lower risk of causing foodborne illness than raw, unpasteurized buttermilk due to the process of killing harmful bacteria during pasteurization. Regardless, proper storage and handling are still crucial to preventing spoilage.

Harmful Bacteria

Harmful bacteria can grow in dairy products like buttermilk if it is not stored and handled properly. Lactic acid, produced by the fermentation of lactose, gives buttermilk its distinct taste and acts as a natural preservative. However, this is not enough to prevent all bacterial growth.

Some common bacteria that can cause foodborne illness in dairy products include:

  • Listeria monocytogenes
  • Salmonella
  • Escherichia coli (E. coli)
  • Campylobacter jejuni

When these bacteria grow in buttermilk, it raises the potential for food poisoning if consumed.

Food Poisoning

Consuming spoiled buttermilk can cause food poisoning due to bacterial growth. To reduce the risk, always ensure that the buttermilk is safe to consume by checking the expiration date, smell, and consistency.

Factors that contribute to spoilage and bacterial growth in buttermilk include:

  • Warmer temperatures (above 40°F/4°C)
  • Prolonged exposure to room temperature
  • Contamination from other foods or utensils
  • Punctured or damaged packaging

To ensure buttermilk is safe to consume, consider the following:

  1. Verify the expiration date on the package.
  2. Check the smell of the buttermilk. Spoiled buttermilk will have a strong, unpleasant odor.
  3. Examine the consistency. If it appears curdled, thick, or slimy, discard the buttermilk.

By taking these precautions, you can enjoy buttermilk safely and avoid the risk of foodborne illness.

How To Tell If Buttermilk Is Bad The Best Way

Using and Storing Buttermilk

Baking and Cooking

Buttermilk is often used in recipes such as pancakes, waffles, and baked goods due to its acidic properties. Its acidity helps to tenderize meat, and the calcium content can also promote browning, resulting in a pleasing texture. To get the best results, use buttermilk in recipes that specify it, as it may have different fermentation levels, consistency, and acidity from other types of milk.

Freezing and Thawing Buttermilk

Buttermilk can be stored in the refrigerator for up to two weeks, but if you want to preserve it for longer, freezing is an option. To freeze buttermilk:

  • Pour the buttermilk into ice cube trays or individual portion-sized containers.
  • Place the trays or containers in the freezer.
  • Once frozen, transfer the buttermilk cubes to an airtight container or plastic freezer bag.

To thaw buttermilk, place the desired amount in the refrigerator for a few hours, or use the defrost setting on your microwave. Note that the texture may change slightly after thawing, but it will still work well in most recipes. It’s best to use thawed buttermilk in baking or cooking, rather than for drinking or using in cereal.

Making and Keeping Homemade Buttermilk

If you prefer homemade buttermilk, here’s a simple recipe to make cultured buttermilk using just two ingredients:

  • 1 cup of milk (avoid ultra-high temperature (UHT) pasteurized milk)
  • 1 tablespoon of lemon juice or distilled white vinegar
  1. Combine milk and lemon juice or vinegar in a clean jar or container.
  2. Stir the mixture, then let sit at room temperature for 10-15 minutes until it thickens and curdles.
  3. Once thickened, cover the container and store it in the refrigerator.

Homemade buttermilk will last for up to 2 weeks if stored properly in the refrigerator. Since it contains live lactic acid bacteria, which are beneficial probiotics, it may continue to ferment over time, so the consistency and flavor may change slightly. However, this does not mean that the buttermilk has gone bad. To increase the shelf life of your homemade buttermilk, follow these guidelines:

  • Store it in a clean, airtight container.
  • Keep the container in the back of the refrigerator, where the temperature is more stable.
  • Use clean utensils when handling buttermilk to prevent contamination.
  • Check for any signs of mold or off smells before using.

Substitutes and Alternatives

Powdered Buttermilk

Powdered buttermilk is a convenient and reliable alternative to fresh buttermilk. It is made by removing the liquid from buttermilk, leaving behind the solids in the form of a powder. To use powdered buttermilk, simply mix it with water according to the package instructions. This substitute is great for baking and cooking, and has a long shelf life. Some other benefits of powdered buttermilk include:

  • Easy storage
  • Consistent flavor
  • Cost-effective

Yogurt and Cheese

Yogurt and cheese can be used as substitutes for buttermilk, especially in baking recipes. For yogurt, use plain, unsweetened yogurt to maintain the acidity of buttermilk. Greek yogurt or sour cream can be thinned with a bit of water or milk to achieve a similar consistency as buttermilk.

Cheeses like cottage cheese or queso fresco can also work as buttermilk alternatives. These cheeses should be mashed or blended until smooth, then mixed with water or milk to adjust the consistency.

Vinegar and Lemon Juice

Vinegar and lemon juice can be used as a buttermilk substitute for their acidity, which helps replicate the tangy flavor and react with baking soda or powder in recipes. To make a vinegar or lemon juice substitute:

  1. Measure 1 tablespoon of white vinegar or lemon juice into a measuring cup
  2. Fill the cup with milk (any type) up to the 1 cup mark
  3. Let the mixture sit for a few minutes until it begins to curdle

This substitute works well for baking, but may not be suitable for recipes where the buttermilk plays a substantial role in the taste or texture.

Buttermilk’s Unique Flavors and Benefits

Tangy Taste and Buttery Flavor

Buttermilk has a distinct taste and flavor, which sets it apart from other dairy products. Its tangy taste comes from lactic acid bacteria, which ferment the lactose in milk. This fermentation process gives buttermilk its unique, slightly sour flavor. In addition, buttermilk has a rich, buttery taste that is a result of the traces of butter left behind during the churning process.

Acidity and pH Levels

The fermentation process that gives buttermilk its tangy taste also affects its acidity and pH levels. Buttermilk has a pH ranging from 4.0 to 4.5, making it more acidic than regular milk. This acidity has some practical benefits – it can help tenderize and flavor meat when used as a marinade and, when used in baking, its acidity reacts with baking soda or baking powder to create a fluffy texture in baked goods.

Nutritional Value

Buttermilk is a nutritious drink that offers some health benefits. Here’s a quick overview:

  • Protein: Buttermilk contains about 8 grams of protein per cup (240 mL). Protein is essential for building and repairing tissues in the body.
  • Potassium: Buttermilk is a good source of potassium, an essential mineral that helps regulate blood pressure.
  • Calcium: One cup of buttermilk has approximately 284 milligrams of calcium, which is essential for maintaining healthy bones and teeth.

In addition to its nutritional value, buttermilk has several uses in recipes due to its taste, acidity, and texture. It can be used in savory dishes like fried chicken or salad dressings and in sweet recipes like pancakes, waffles, and muffins.


In conclusion, identifying bad buttermilk is mainly about observing its appearance, smell, and taste. By regularly checking these factors, you can ensure that the buttermilk you consume is fresh and safe to use. Remember, proper storage plays a vital role in maintaining its quality as well.

To recap, consider the following points when assessing buttermilk:

  • Check the expiration date on the container
  • Look for changes in appearance, such as clumps or mold
  • Note any off or sour odors
  • Taste a small amount to detect spoiled or rancid flavors

By following these guidelines, you will be able to recognize if your buttermilk is no longer suitable for consumption, and make more informed decisions in the kitchen. Stay mindful of these signs and enjoy your buttermilk in all its fresh and delicious glory!

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Cassie brings decades of experience to the Kitchen Community. She is a noted chef and avid gardener. Her new book "Healthy Eating Through the Garden" will be released shortly. When not writing or speaking about food and gardens Cassie can be found puttering around farmer's markets and greenhouses looking for the next great idea.
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