How long can buttermilk stay out of the fridge? I forgot mine over 6 hours out

  • Posted by: Fabiola
  • March 8, 2014


Mrsbsims November 22, 2020
Here it is 2020 and I am thankful for this thread as I have just found that my son left my buttermilk in the car for the last 6 hours.....and it was the last one on the shelf (weekend before Thanksgiving) . I was so upset and then took to the Google to just see if its possible to still use it! Thank you all for your years of comments to help relieve me from going back to that dn store this week! Happy Thanksgiving yall!
Christine M. December 4, 2020
Came here to say the same hahahaha. I needed an answer to this today and very grateful for this thread. Thanks Kevin!
Kevin R. December 6, 2020
Hahaha. Cheers to you both. Happy safe (buttermilk and otherwise) holidays!
(I keep buttermilk in my fridge for periods of time that would make many folks eyes get wide. When it become *very* strong I use it as a seed with whole milk to make a fresh batch. My family has never scruntched a nose or become ill. If buttermilk is some level of sour, it's fine.... but if it's "funky" and cheesy or has any pink coloring, then it needs to be tossed. But that takes probably a week or more at room temp, and months in the fridge.)
Rebecca August 14, 2018
Thanks, Kevin! I left my buttermilk out last night on the counter for 14 hrs and now I’ll have no problem using it. Answering questions years later is never a bad idea :)
Kevin R. December 17, 2019
The internet is crazy powerful. :D

BTW, I still suggest to you and everyone that you can make your own buttermilk from the cultured buttermilk you've bought. Just pour about 1/2 to 1 cup into a large jar (amount doesn't really matter, even a Tbls will work, it'll just take a bit longer) and then top it off with (preferably non-homogenized) whole milk and cover the top with a clean paper or cloth towel, cover it with another towel so it's dark, and let it sit out on the counter for 12-24 hours. You'll have an entire jar of more buttermilk.
It's not unlike sourdough starter, in that if you add some starter to a dough mix and let it sit out fermenting for several days, eventually the entire dough will be the "starter".
Gail July 20, 2018
I am so happy Kevin answered a two year old question, even if only now. I still read old posts because of the subjects. I learn a lot doing this and get answers to questions I have. KEEP POSTING, FOLKS!
George July 20, 2018
Bought buttermilk and forgot about it in the car 12 hours later (temperature was probably at least 90 degrees). Since the carton was sealed and buttermilk is pasturized, I just shook up the contents to make it smooth again and made buttermilk biscuits. Everyone ate them and we are fine.
GC December 16, 2017
Now it's 4 years, but Kevin is exactly right. Cultured my own buttermilk for years, and the actual culture is heat loving, technically, "thermophilic". It only works when it is warm. Just check for mold or strange taste or smell, if you are worried. When it warms up, and the cultures reactivate, it will become more tart and acidic perhaps, but it has not gone bad, especially for cooking.
Leanne J. August 14, 2017
I also appreciate Kevins answer, as it was most informative, and I am 3 years after the original question!
Thanks for the info!
Kevin R. August 14, 2017
No worries. :) petitbleu hit it on the money as well. It seems many are rediscovering cultured and fermented foods more and more (myself included a number of years back) and learning about it all is great. In most cases these fermented and cultured foods were *because* there was no refrigeration available back then. We've got the best of both worlds, and that's the reason I can keep buttermilk on hand and ready to use for a month or more before I have to toss it --- and that's usually just because it's far too strong and not very appealing any longer, but it isn't dangerous. Working with these foods reconnects you to your senses I think, and not just a printed label. That's not to say food safety isn't a seriously important thing, just that many have never understood the how/why of quite a bit of it.
At any rate - I'd use buttermilk left out for days personally, though at that point I'd have to pour the whey off and thin it with regular milk. At room temps, the cultures multiply rapidly!
Shelli S. December 31, 2015
Thank you Kevin! I like reading current answers as well as old answers. I was concerned with my buttermilk. I had just bought it brand new last night from the grocery store and never opened it. I just forgot to put it in the frig. I planned on using it for red velvet cake. It sat out for 12 hours, but was still in the bag and at room temp this morning, which is about 65-70. I still plan to use it after reading you answer Kevin. I'll look for curds, but I bought a really good brand and I'm sure it took at least 4-5 hours to return to room temp.
Kevin R. December 20, 2015
This is a strange buttermilk conversation I just stumbled on. The answer is simple - if it is 'fake' buttermilk that you've made with pasteurized milk and citrus juice, it's now spoiled for certain. If it is store-bought *cultured* buttermilk it's probably fine as long as it was a good brand with still-live cultures; if that's the case all that will happen is the culture will accelerate its growth and the buttermilk will be stronger/more tart hours later. You have to leave buttermilk out a considerably long time (perhaps days) before wild bacteria will be able to take enough hold to genuinely spoil the milk.
If it were me, I'd pour some of it in a large jar, fill it with milk and create MORE buttermilk by letting it sit another 6 hours. It will last in your fridge for weeks, if not months.
Kevin R. December 20, 2015
... Even if the buttermilk reaches the point that it separates into curds, it hasn't "spoiled" it's just become curds and whey and is probably still edible, again, provided the cultures in that brand were good live ones. Until actual molds take hold (that tell-tale green or blue fuzz) the buttermilk is probably fine.
nutcakes December 20, 2015
You don't really need to answer questions that were asked two years
Kevin R. December 20, 2015
Well, no and normally I would not, but like many forums, this will come up in a search (the way I found it) and certainly more folks than just those who replied here have viewed and will view the topic.
Jamirah F. December 17, 2019
Exactly. Like me, I am looking this up and it's 2019. Your answer is very helpful.
Kevin R. December 17, 2019
:D I just got an email about this reply, and had forgotten about this thread *completely*. So, awesome, mission accomplished! Haha
Sheryn C. January 1, 2020
January 1, 2020 now((: & I'm very pleased with longevity of this topic! Thank you!!!
dymnyno March 10, 2014
Just use common sense. If it separates when you pour it, it is probably not useable. How warm is your kitchen? What kind of buttermilk is it? Preservatives?
petitbleu March 9, 2014
The thing to remember about buttermilk is that it is cultured, which means that by the time it gets to your kitchen, the acidity has dropped quite a bit. This acidity is not only what reacts with baking soda in baked goods to achieve a rise, but also what prevents harmful bacteria from colonizing the milk, as lactic acid bacteria ("good" bacteria) have already taken over and will generally out-compete other types of bacteria. This is also why cheese is possible and why most of us know by now that buying yogurt past its expiration date is usually okay. If I left out buttermilk for 6 hours, I would probably still use it. If you asked this question on a French cooking forum, most people would probably deem it still safe to use (the French seem to be a bit less paranoid about refrigeration than Americans). However, if it makes you nervous to use it, just toss it.
Kevin R. December 6, 2020
Just a quick clarification to prevent confusion of others: the acidity of cultured yogurt will INCREASE, not drop, over time. The pH value drops, e.g it becomes more acidic (as the cultures continue to feed on the milk sugars and produce additional lactic acid as the bi-product of the process). This happens much more quickly at room temps than refrigeration temps.
Just wanted to clarify that for folks reading here. It's bananas how much this page is still referenced years later.
(I agree with everything said in this response, except that in my opinion there's absolutely no reason to toss warmed buttermilk unless it is the UNcultured type, e.g. fake buttermilk).
Gabriella March 9, 2014
Also if you really don't feel comfortable and you want to scrap it, it's so easy to make your own. Just take a cup measure and add 1Tbsp lemon juice or white vinegar and then fill the cup measure the rest of the way with plain milk(whatever you have handy). Mix it up and let it sit for a few minutes and you're good to go. You can adjust for the amount needed (1.5teaspoon for half a cup or 2T for 2 cups etc) good luck!
Gabriella March 9, 2014
I've used homemade and store bought buttermilk that I've kept on the counter overnight and then used in baking cakes so that it will be room temperature and I have never had a problem with it turning. I wouldn't worry about it unless it's really clumpy (not just slightly separated) or if you see spots of yellow which can mean it's rancid.
ATG117 March 9, 2014
I don't think anyone can confidently tell you to go ahead and use it without risk. And because recreating it is rather easy, I'd highly recommend replacing or subbing. As others have mentioned you can use milk and lemon juice or milk and yogurt mixed together.
sexyLAMBCHOPx March 9, 2014
Smell taste aside, try pouring some rancid buttermilk in a glass you'll see it!
Pegeen March 8, 2014
Felicia, I'm curious as to why you say the smell test doesn't work with buttermilk?

Fabiola, depends on the room temperature your buttermilk rested at. Six hours is a long time at normal room temp (65 to 70 degrees). If you throw it out, you can make your own buttermilk pretty easily:
Put 2 tablespoons lemon juice or white vinegar in a measuring cup. Add 1 cup regular milk to fill to the 1-cup mark. Stir, let stand for 5 to 10 minutes at room temperature. Curds may form - that's fine. Use or refrigerate it. Stir a little to smooth out curds before using.
Felicia M. March 9, 2014
Pegeen: Doesn't buttermilk already smell a little sour in the first place? As you can tell, it's been a while since I've used it.
nutcakes March 8, 2014
For my own use, I'd have not hesitation to use it.
Felicia M. March 8, 2014
*grimace* It's probably safest to discard, unless you left it near a window and it's fridge temperature outside. Dairy products are iffy, especially buttermilk since you can't sniff it to smell whether it's still good.
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