How to Tell if Buttermilk is Bad: 4 Signs

Signs of Spoiled or Bad Buttermilk

The texture is thick and chunky instead of smooth. Buttermilk tends to be a little thicker than milk and it naturally has tiny lumps in it, so it's good to shake it well. Pour some into a cup and look at its consistency. It should be smooth, but if it's really thick and has clumps or chunks, the buttermilk has gone bad.

The buttermilk smells strong and sour. Shake the buttermilk really well and pour some into a cup. Be brave and give it a sniff! Buttermilk should smell tangy, but pleasant if it's good. If you notice a really strong, gross, or terrible sour smell, the buttermilk has gone bad. If you're not sure if the tangy smell is normal, check for other signs of spoilage before you toss or use the buttermilk.

You see mold on the buttermilk or it looks discolored. Buttermilk should be a pale creamy color, so if you pour it into a cup and notice funky mold or strange colors, throw it out. For instance, buttermilk might develop pink, gray, or fuzzy patches if it's bad.

The buttermilk has been at room temperature for over 2 hours. In general, dairy products like buttermilk can't be left out or they'll spoil. If you've accidentally left your buttermilk out, but it's been less than 2 hours, just get it in the fridge immediately and plan on using it as soon as possible. If it's really warm where you live (over 90 °F (32 °C), play it safe and throw away buttermilk that's been left out for 1 hour or more since bacteria grows faster at warmer temperatures. If the buttermilk's been out over 2 hours, it's best to toss it—you don't want to risk dangerous bacteria that can cause severe illness.

How long is buttermilk good after you open it?

Opened buttermilk will stay good for 2 to 3 weeks in the fridge. Store the buttermilk in a sealed container, so it stays fresher longer. It's also a good idea to label the container with the date you opened it. Plan on using the buttermilk within a few weeks—it continues to lose its rich flavor the longer it's stored. Keep the buttermilk in the main body of the fridge, not the shelf door since it's too warm there. Ensure that your fridge is set to 40 °F (4 °C) or below to extend the shelf life of the buttermilk. For longer storage, freeze buttermilk for up to 3 months. Then, thaw it in the fridge overnight before you bake with it.

Can you consume buttermilk past its expiration date?

It's safe to use unopened buttermilk within 1 week of the expiration date. Some packages of buttermilk will even tell you that it's good to use a certain number of days after the sell-by or use-by date, so check the side of the container. As long as the buttermilk doesn't show signs of spoilage, it's safe to use. If you're a little concerned about using the buttermilk, use it in a baking recipe so it will be cooked at a high temperature.

What happens if you use spoiled buttermilk?

You might get food poisoning symptoms. If you get a mild case of food poisoning from bad buttermilk, you may experience cramps, nausea, or vomiting—these usually develop within a few hours of eating the food. Usually, the symptoms clear up on their own within a few hours. Some people might get more serious poisoning if they ate a lot of bacteria or if they're immunocompromised.