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How can you tell when buttermilk is bad? [moved from Home Cooking board]

It's already sour...

I have some, only two days over the expiration date. It smells the same as before, sour. I want to make some pumpkin bread with it tonight.

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    1. What if it's about 2 weeks past its sellby date, and still smells the same, sour?

      Is it one of those "use it until it's chunky" sort of things, or what? I'm a total buttermilk novice, apparently.

      1. Maybe I'm off base, but since buttermilk by and large is a substitution for what cookbooks used to call ``sour milk,'' i.e., milk that had gone off, and since it is always pretty thoroughly heated when you cook with it, I've always thought that slightly funky buttermilk was okay in biscuits and spoonbread and pancakes and such, although not in something like buttermilk mashed potatoes where it is just stirred into a hot mass and not cooked. The increased acidity actually gives a better rise in biscuits.

        1 Reply
        1. re: condiment

          Real buttermilk is not merely sour milk. Sour milk -- milk that has gone bad -- tastes different and does not have a proper texture; different organisms are responsible for "going bad", as it were.

          Real buttermilk is virtually impossible to get in US supermarkets (though here in eastern New England, some of us are delighted by the news that Kate's Butter of Old Orchard Beach in Maine may soon start distributing real buttermilk in select markets). Real buttermilk was the foundational food of the Irish, including my grandmother and her sister; potatoes sat atop that foundation, as it were.

          What we get in US markets is a cultured milk product that seeks to emulate certain aspects of buttermilk in terms of acidity and viscosity. It's a great product to have in the absence of the real thing. But it too is not merely soured milk.

        2. Your buttermilk sounds fine. I've had some that was still good WEEKS past the expiration date. It's bad when it separates into thin liquid with chunks.

          4 Replies
          1. re: LT from LF

            Yeah, I look for the chunks and thin liquid sign too. Also, taste it - sometimes you can detect bitterness even before the chunks+thin liquid state. If it was bitter, I wouldn't use it.

            1. re: sweetTooth

              Well, yes...of course I'd taste it if I didn't see the telltale separation....

            2. re: LT from LF

              but many recipe calls for "well-shaken" buttermilk. So if I shake it, would the liquid and chunks re-incorporate and fool me? :P

              1. re: OnceUponABite

                It will never again coalesce into something you'd want to drink or cook with. Plus you can see the thin liquid/chunk combo before you shake it.

            3. There was something we called clabber, too. I think that's also soured milk, but it's delicious, at least in my memory.

              1. I agree that it's fine unless it's chunky. It keeps a long time. BTW you can paint clay pots with old buttermilk to encourage moss to grow.

                1. Oh, c'mon, if it's chunky, just shake it up! Buttermilk's not bad until it's fuzzy!

                  1 Reply
                  1. re: babette feasts

                    I don't get it. Buttermilk is chunky when you purchase it. Do you mean extrasuperduper chunky?

                    btw... I just checked the date on my buttermilk. Expired back on the 23rd of November, but still going strong! I just used it a couple days ago to marinate pork filets for tonkatsu, and made buttermilk corn bread yesterday... and I'm still here to tell about it! :)

                  2. I've also been using it well past the sell-by date in my baking to no ill effect. I shake it and smell it, but maybe I should be tasting it too.

                    1 Reply
                    1. re: julesrules

                      It'll taste scary if it's bad. No matter what, it can't hurt you. I'd say it could last a month.

                    2. I've never tasted buttermilk, so I'm not sure what sort of flavor constitutes "bad." I've got some buttermilk here for the first time ever but I'm not sure if I can use it. The sell-by date was Nov 10 and it is now Jan 1. I've read what other people are saying here, and I don't see any lumps in this old stuff...just looks smooth. So do you think it's safe as long as I only bake with it??

                      1. I've heard some people make more buttermilk by adding more milk to a little leftover buttermilk and letting the bacteria do their thing in the fridge. As to how much of each part and how long, I am not sure. I have some propagated in the fridge since before Thanksgiving and I'm a little afraid to take a look.

                        1 Reply
                        1. re: vsoy

                          Ok, just cleaned out the fridge, wiping down shelves, throwing out ancient condiments and I bravely peeked in the buttermilk carton. It didn't smell bad, but I saw a small, dark furry mold growing on the wall of the carton. So much for that experiment :P

                        2. So here's a different(but related)question--what's the word re freezing buttermilk, when you've only used part of a carton for that banana bread recipe?

                          1. I drink lots of buttermilk so I ought to know. Ive had buttermilk well over 2 weeks beyond the carton date and it's still good.

                            1. I desperately wanted to make some cornbread, but I neglected to purchase a new container of buttermilk while I was out this evening. My buttermilk in the fridge has a date of 12/5/06 on it. It smells the same to me as it always has (stinky & soured). My question is - can I still use this "expired" buttermilk in my cornbread? I definitely don't want to taste the stuff - if it tastes like smells, my pregnancy morning sickness may kick in high gear!

                              1. If it looks like cottage cheese and it's suppose to be buttermilk....might be a tad OFF hahahahaha :-)

                                1. My buttermilk (just opened well before expiration date) has orange spots floating all over it. smells okay but looks freaky. What up?

                                  11 Replies
                                  1. re: MarshmellowFlu

                                    I seem to recall that in the past sometimes buttermilk has been offered with "butter bits," little yellow chunks floating around in it--purely a marketing gimmick of course. Could that be what it is?

                                    As stated by others previously in this thread, buttermilk is actually good well beyond its pull date, so there no reason to think yours, which hasn't reached its pull date, isn't fine. Anyway, all milk products are supposed to be good several days past their pull dates, which are actually sell by dates not use by dates. And buttermilk is a cultured milk product (like yoghurt, sour cream, cottage cheese, cream cheese, etc.), and cultured products, having already been transformed by bacterial action, last a lot longer than fresh products such as milk. I have used buttermilk a month or more past its date and the results have been fine. Unopened, cultured products should last 4-6 weeks past date without problems.

                                    So you should be good.

                                    1. re: johnb

                                      That must be it. I used it to make pancakes and they were fine. Also the buttermilk tasted ok. I coudn't find anything about it on the internet. Kooky. Thanks for your reply!

                                      1. re: MarshmellowFlu

                                        I have a carton of buttermilk that I opened almost 2 weeks ago. The expiration date is still a week from now. It is chunky before I shake it. Does opened buttermilk only last a few days?

                                        1. re: mice

                                          It shouldn't. I've kept open buttermilk for a few weeks at least. If it's a little clumpy it's usually still ok.

                                          1. re: mice

                                            I go by taste. I have a jug that is a 1 1/2 weeks from expiring and is getting lumpy. Still delicious.

                                            1. re: mojo66

                                              I've used buttermilk that was 6 months past it's expiration. Everything tasted fine (well, excellent actually) and no one got sick.

                                              1. re: tjsnell

                                                I'm glad I found this thread. I recently bought buttermilk for the first time, and was wondering how to tell if it's gone bad. This helps me alot, so many thanks to all of you who responded to this!

                                                Is buttermilk -supposed- to taste like thinned-out yogurt? Sour, almost lemony? HOW THE HECK can something that tastes so odd, be so darned good in baked goods? I'm amazed. I love sour foods, but this takes the cake for me.

                                                I wish I could try the real stuff, to compare.

                                                1. re: Honeychan

                                                  >>>Is buttermilk -supposed- to taste like thinned-out yogurt? Sour, almost lemony? <<<

                                                  In a word, yes. They are both cultured milk products (ie yeast has gotten in there and done its thing). Thus it is similar to a wide range of cultured dairy products including yogurt and others. For example, I find that one can make a passable lassi-like beverage at home by using buttermilk and adding whatever ingredients are appropriate for the lassi one wishes to emulate; just adding some sugar and a few ice cubes makes for a very bracing, and almost addictive, lassi-like summer beverage.

                                                  1. re: johnb

                                                    John, you are right that buttermilk is a cultured milk product, but the culture bacteria not yeast.
                                                    Lassi comes from Punjabi cuisine which is rich in the use of dairy. My family is not from Punjab and so I don't know if Punjabis make lassi with yogurt or buttermilk. But in my mom's kitchen, lassi was always made with buttermilk. Best way to use up all that buttermilk from making butter every other week.

                                        1. re: jellobelt

                                          I think people are confusing the orange/yellow chunks, some buttermilk manufactureres like Knudsen add small Butter chunks to their buttermilk, I've been drinking buttermilk for 60 years and have never experienced orange bacteria growth.

                                      2. It seems bad to me when I first open the bottle! So I figured that it's good for awhile... I doubt it's going to keel over and die on the printed date.