Psst... We're working on the next generation of Chowhound! View >
HOME > Chowhound > Home Cooking >
Sep 16, 2010 11:38 AM

Canning question: bubbles in sweet potato butter?

I made some sweet potato butter in the crockpot overnight and canned it this morning. I was careful to keep everything hot and sanitary until the butter was safely stored away in the jars, but I'm still not sure all went well.

The trouble is bubbles. I went around the inside edge of each jar with a thin knife to remove bubbles before putting the lids on. But when processing was done (the lids had sealed while still in the boiling water) I saw bubbles, sometimes big ones, at the bottom of some of the jars. I know the butter was thin enough to allow bubbles to rise during processing, so I'm not afraid that they're full of dirty unsterile air that couldn't boil its way out. I think it's just that, although I put the sweet potatoes through the food mill twice (once before adding the rest of the ingredients and once near the end of cooking), the butter is still slightly chunky and doesn't adhere perfectly smoothly to the walls of the jar.

I've seen some bubbles even in commercially canned jams, so I suspect it's OK. Opinions please?

  1. Click to Upload a photo (10 MB limit)
  1. Beg, borrow or steal a vacuum sealer with a canning jar attachment. The suction will draw every last bit of air (in the form of bubbles) from the jar. Very fast, very handy.

    5 Replies
    1. re: Ernie Diamond

      So it removes the bubbles but leaves the headspace alone?

      1. re: csdiego

        well, the headspace will increase somewhat as the volumes of air are drawn from the product so no, it doesn't leave the headspace alone, exactly. However, it does not suck liquid into the air and down the tube, if that is what you mean.

        Am I understanding the question?

        1. re: Ernie Diamond

          I think I see what you're saying--the sealer brings all the air out of the filling into the headspace. I'm not into gadgets so I can't see myself buying a vacuum sealer just for the few batches of jam or chutney I make each year, but it's interesting to know that it's out there, thanks.

      2. re: Ernie Diamond

        Could you talk more about your vacuum sealer? Pros cons, what type you have? I am wondering if i should put it on the christmas list. I do freeze and can a lot. Thanks

        1. re: geminigirl

          I have a FoodSaver, nothing fancy, just something from Target. I don't remember what I paid.

          I find it very handy for freezing things like meat. Is it a vital tool? No. I think that foods generally freeze better than we think they do and those that I tend to freeze most often (soups, stews and stocks) do just fine in a plaztic bag with the air expelled.

          I go on meat benders, though and when I am staring at ten pounds of blood sausage or racks of terrines or even lots of little cups of rillettes, I am very glad to have it on hand.

          I suggest doing your homework on it. It is very easy to use and if I had a family to feed or if I hunted big game, I am certain that I would be doing more freezing and packing with it. I could see it being a very handy tool for those of us who cook en masse and then have portions to dole out.

      3. Did you water bath can it or pressure can it?
        Without knowing the ingredients, sweet potato butter sounds like something that would be very hazardous *not* to pressure can... regardless of bubbles.

        19 Replies
        1. re: blue_skiesMN

          I water-bathed it. That's what the recipe said to do. Granted, it didn't come from the USDA. But I'm pretty sure there's enough apple cider in there to keep it safe. It certainly had a tart little bite. And then there's plenty of sugar too.

          1. re: csdiego

            I'm going to chime in here about canning food safely. I'm all for not being scared about canning - if you are canning fruits or pickles, you are totally fine. Unfortunately, sweet potato butter is NEVER safe to be canned. Sugar doesn't prevent botulism, only temperature and acidity. The texture of sweet potato butter is such that the interior of the jar can never reach a temperature (even with pressure canning, let alone BWB) or the acid in your apple cider to reach the center to make sure the pH is <4.6 in the center of your jar to safely kill botulism spores. All it takes is one botulism spore to stay alive...if it does, it will propogate in the anaerobic environment of your canning jar.

            I'm a big advocate for canning food safely, so I had to let you know this. If you have any more questions about canning feel free to shoot me an email...check out my blog at and you can find my email address there.

            1. re: momskitchen

              If one can put away apple butter or applesauce, why would sweet potato or pumpkin butter be diffferent? It's important to bring the butter up to boiling/bubbling so the temp is consistent throughout before pouring into sterilized jars. But, applesauce and butter can both be canned bwb safely...or would it be safer to do a sort of sweet potato chutney with the vegetable in chunks? I didn't have any trouble with membrillo (quince paste) or pumpkin butter a few years ago, but I hate to think I put our family in danger unknowingly. (Though no one ever got sick, maybe we were lucky?)

              1. re: amyzan

                This link has a report on why it's not safe to home can pumpkin/winter squash butters and purees:

                Since sweet potatoes and yams can be used interchangeably with pumpkin/winter squash, I would personally not risk trying to can it. When I specifically searched sweet potato butter on the same site, it lead to the same link above. However, it can be frozen.

                1. re: morwen

                  Thanks, morwen and csdiego. The link was particularly interesting. So, I'm rather glad we got the pumpkin butter eaten without incident, and won't be doing that again. I suppose commercial producers must monitor ph carefully in each batch then, or it wouldn't be available in the markets...

                  1. re: amyzan

                    Commercial producers also have machinery far tougher than that available to home cooks to force and hold temperatures long enough to kill the bad critters. Mostly. There are always recalls.

                2. re: amyzan

                  My guess is that the official answer has to do with the acidity of apples vs. sweet potatoes/pumpkins: apples are presumably acidic enough, while the orange fall vegetables aren't. On the other hand, without wanting to get anyone in trouble, the person who published the recipe apparently trusts it enough to sell the result at a farmer's market, so... I do know that the sweet potato butter I did yesterday had exactly the same consistency as the plum jam I put up today, so from that perspective air bubbles shouldn't be a worry.

                  I'm aware that the effects of botulism are not pleasant, but having been really careful to keep everything sanitary with this recipe, I'm taking my chances. I think this is one of those issues like eating undercooked eggs or drinking an occasional glass of wine during pregnancy: the 100% safe position is never to do it, but there is some wiggle room outside the official guidelines. I don't think things are as strict in other countries: a British friend of mine gave me a marmalade recipe from Nigella Lawson (as published in the UK) that calls for reusing a commercial jam jar, just boiling it and keeping everything hot, etc. She used that recipe to make jam for a fundraiser, and nobody died. [When I made it, I did use Kerr jars with fresh lids.] When I was a kid we sealed jelly jars with a thick layer of paraffin and never had a problem. I sealed jars as late as 10-12 years ago by just turning them upside down and waiting for the seal to pop. So while I'm willing to meet the new guidelines by sticking to commercial lids and adopting the BWB for jellies and jams, I'm only taking the food-poisoning worries so far. I appreciate the official advice, even if it did go beyond my initial question about bubbles, but what I'm doing is my decision.

                  1. re: csdiego

                    No need to get defensive, just pointing you in a direction that has some facts and reasons to support some points other posters brought up. I would really prefer to be able to can the stuff, but I also prefer not to take any chances with my grandkids, so I freeze it.
                    I also use to reuse commercial jars especially ones that accept 2 part canning lids. The only reason I stopped was because the damn things kept cracking on me while processing. They couldn't handle the temperature changes because they weren't designed for repeated use. I got tired of binning all my hard work.

                    1. re: morwen

                      Well, maybe I'll add sweet potato butter to the long list of canned goods that are too much trouble/too risky for the future. But I'm not throwing this batch away.

                      Cracking, wow. That sounds annoying. I have a few commercial jars I've been using since 1996 and they're still going strong. What do you use instead? Or do you just buy fresh jars each time?

                      1. re: csdiego

                        The beauty of canning is that you can reuse your canning jars over and over and they won't break. I buy used canning jars all the time at garage sales. The reason why commercial jars break so easily is that they often put a coating on those jars and if they get scratched, just by even rubbing them together a little, it will initiate a crack, especially the Classico pasta sauce jars that look like Mason jars. Happy canning!

                        1. re: momskitchen

                          Freecycle is also a great source for canning jars. Of course, some commercial jars tend to show up in the mix, but as it is all free, I don't mind sorting those out before canning.

                        2. re: csdiego

                          I use Ball or Kerr jars that are tempered to withstand temperature changes and made specifically for home canning.. As momk says they are reusable over and over again as are the rings but not the lids. Mason is the name of the man who invented the process for tempering the glass, thus the phrase "Mason jars". However, even though those pasta jars she refers to say Mason on them don't be fooled. They are not true Mason jars. That's a marketing ploy to encourage the consumer to associate their sauce with home made.

                          Here in VA, you must create your preserves for sale at farmers markets in a certified kitchen that gets at minimum, a yearly inspection by the state. Your water source must be tested and your recipes must be submitted to (in my area) Virginia Tech for testing and safety approval before being able to sell to the public. Bringing a home kitchen up to code and paying for the inspections and testing is a very heavy investment. I just checked into this a week ago when considering the possibility of having my kitchen certified. Because I run a small B&B, I have my kitchen voluntarily inspected yearly although I'm not required to in this state. But I still can't sell my preserves to my guests because I am inspected but not certified. Do all people who sell their preserves at farmers markets here work out of certified kitchens? Of course not. They're skirting the law and if caught, they'll be subject to heavy fines at the very least. I find that those people are easy to spot at the markets and I don't buy from them no matter how tempting their goods. Not because they're skirting the law (that's their problem) but because I have no reference to know how clean they work. or how educated they are about what they're making. I know this is all way off topic and I so support our local food producers, but I also know that people with the best of intentions could make my family very, very sick. So I'm still careful at farmers markets as well as wary of some canning recipes on the internet.

                          1. re: morwen

                            I see, by commercial jars you meant reusing the jars from something bought at the supermarket. No, I've got Ball and Kerr. I do notice that the newer Ball jars are a lot thinner than my beautiful greenish-bluish older Kerr ones :S

                            1. re: csdiego

                              Oh I get it now, CS....yeah, your Ball and Kerr jars should be fine. Even if they are thinner now that they used to be. With advances in technology, they can make jars better and lighter, and that's a good thing! They are less heavy to move around your house for storage, and also reduces their carbon footprint to transport to stores from the factory. (stuff that weighs more burns more fuel to move)

                            2. re: morwen

                              @morwen I have been using this new kind of jar lid that is completely reusable...they are called Tattler lids and they have worked out well for me this season. They cost about $10 per box, but they can be reused infinitely. I am using these lids for all my non gift canning.

                              1. re: momskitchen

                                I saw that Marisa over at Food in Jars is using them too. I think she's going to do a post on them soon. I've never come across them before and I'm definitely intrigued.

                                1. re: morwen

                                  I love 'em. They are made in Michigan, so a couple stores around Ann Arbor carry them. I think they can be ordered online, though. They are BPA free, if you are worried about that.

                                  1. re: momskitchen

                                    I figure at my age it's far too late for me, and probably for my kids, but not for my grandkids.

                      2. re: amyzan

                        Apple butter and sauce has a pH of <4.6 and it also isn't so dense as to interfere with the heat transfer to the center of the jar. Quince paste is fine because it has a low pH and it doesn't solidify until after it cools...pumpin butter isn't safe to be boiling water bath or pressure canned. There's lots of non food safe canning recipes out there on the web....

                3. It's probably just air bubbles and nothing to be concerned about. But I would love to see the recipe you used. I'm interested because pumpkin butter isn't supposed to be water bathed even with added sugar and acid, which bums me out. I would suppose it to be the same for sweet potato butter. Could you put up the recipe and the source please?

                  1 Reply
                  1. re: morwen

                    Here's the link:


                    I made a smaller batch with the same proportions, and changed the spices a bit.

                  2. I put up spiced pumpkin butter several years ago, processed in a water bath like your recipe. Though there were air bubbles (small ones) in the jars, I had no issues with spoilage. I think the last jar was eaten in late summer, and it was fine, if the spices had diminished in flavor a bit. I've also put up quince jam, which is similarly thick, and not had issues after a water bath. I'd bet money you're safe with your sweet potato butter, too.