Canning Mistakes: “But, My Jars Sealed”

The AnswerLine Team receives many phone calls and emails regarding canning mistakes—incorrect processing time, canner wasn’t vented, wrong size jars used, forgot to add acid to tomatoes, incorrect headspace, hot water canner used for low-acid foods, elevation not considered–just to name a few.  Mistakes happen but the biggest mistake of all is the assumption, “BUT, MY JARS SEALED!”

A SEALED JAR DOES NOT EQUAL A SAFE PRODUCT if a canning mistake has occurred, a recipe has been altered, or if an untested recipe was used.  In the canning process, jars of food are heated to destroy pathogens, expel air, and create a vacuum seal.  While this process provides shelf stability, it is also the perfect environment for food borne bacteria, especially Clostridum botulinum, to germinate and produce toxins when a tested canning procedure is not followed.  In that ‘sealed jar,’ conditions favorable to producing the “perfect bacterial storm” exist:
‘DANGER ZONE’ TEMPERATURES that allow for bacterial growth (40⁰F – 120⁰F),
ABSENCE of OXYGEN (anaerobic) resulting from the air being driven out during processing, and possibly a LOW ACID food.  (Foods high in acid, like most fruits, or foods to which acid was added, such as vinegar to pickles, are less susceptible to bacterial growth.)


Canning mistakes can only be rectified in the first 24 hours.  Within that time, they can be reprocessed, frozen, or refrigerated for quick use.  After 24 hours, the food needs to be disposed as it is no longer safe.  This is also true for jars whose lids did not seal.

Reprocessing means following the same processing that would have been done if starting with fresh food—empting and washing jars, reheating, re-filling jars, using new flat lids, and processing with correct time and weight (pressure canning).   Most foods do not tolerate reprocessing very well.  Quality is diminished as they usually end up soft and mushy.  Soft foods, such as applesauce, handle reprocessing better than foods with structure.

When reprocessing isn’t a good option, freezing is.  Remove the contents from the jar and put into freezer containers or bags, label and freeze.  Leaving food in the original canning jars is not recommended unless some of the contents are removed to allow for freezing expansion.

One may also put the jars into the refrigerator and use the contents within 3 days.  This is a good option with small batch canning, but may not be so when 7 quart jars are in question.

Home canning is about following the science to make a SAFE product by preventing foodborne illness.  One can never assume the contents of a sealed jar are safe if there has been any alteration to the recipe or procedure, whether intentional or by mistake.

Marlene Geiger

I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.

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41 thoughts on “Canning Mistakes: “But, My Jars Sealed”

  1. Hi Beja, the USDA recommendation for jams and jellies is 1/4 inch headspace. Headspace is an important consideration. The air in a food, its starch content and the processing temperature determine how much a food will expand. Air expands greatly when heated to high temperatures; the higher the temperature, the greater the expansion. If too little headspace is allowed, the food may expand and bubble out when air is being forced out from under the lid during processing. The bubbling food may leave a deposit on the rim of the jar or the seal of the lid and prevent the jar from sealing properly. If too much headspace is allowed, the food at the top is likely to discolor and in some cases, actually mold. Also, the jar may not seal properly because there will not be enough processing time to drive all air out of the jar.

  2. I put up 30 1/2 pint jars of apple butter about a week ago. I opened a jar to spread some of the apple butter onto toast only to learn is was extremely sweet. I hate to waste all the apple butter but it is definitely too sweet to eat. Is there anyway to fix this? Can I take the apple butter out of the jars and use it as a base to make more? or can I add something to it to lessen the sweetness without ruining it? Can I cook it all again, bring it to a boil, then put it back in clean new jars, lids, rings and reprocess it? What’s the best way to fix my boo boo. ?

  3. Hi Susi,
    The best way to conteract sweetness is to add some acid such as lemon juice or apple cider vinegar. I would suggest starting with one jar and slowly add the acid until you achieve the balance of sweetness you like. If the addition of the liquid makes the butter too thin, you will have to cook down again. Another option would be to prepare a less sweet new batch of butter and mix with your current batch until you achieve the level of sweetness that suits you. In either case, the apple butter needs to be reprocessed in clean jars with new lids or frozen to preserve. Since I don’t know what recipe you used, I’m suggesting that you take a look at the recipe from the National Center for Home Food Preservation to get an idea of how much apple cider vinegar to appples and sugar might be needed to get the balance correct:

  4. I have homemade raspberry jam that I made with a Ball recipe and correctly processed two months ago. They have been properly stored. However, it is in the wrong size jars (making for a party favor). Is it safe to open the jam and heat it to boiling for the time in the original recipe and then seal and process in smaller jars? Basically, going from half pint to 4oz jars, with full processing.

  5. Hi Katherine, I would not recommend reprocessing a jam that doesn’t need it. I am assuming that the jam currently exhibits a perfect jam gel. By reheating and processing it is quite likely that you will break or weaken the gel bonds resulting in a gel of lesser quality. Starting with more raspberries and making a new batch of jam is a far better route to go.

  6. I steam canned tomatoes last night, less than 24 hrs.
    My canner ran out of water, but the gauge was still in the green “canning” area. They sealed and were bubbly when I took them out.
    Should I reprocess?
    If so, do I remove the contents, re sterilize, and completely start over?
    Will the tomatoes still taste ok, I’m not worried if they get soft?
    I’m assuming I don’t need to add more lemon juice.


  7. Hi Jennifer, I am glad that you reprocessed the tomatoes to be certain that they are unquestionably safe. I suspect that the heat was a little high and caused more evaporation than necessary. When a pressure canner goes dry, the consensus is that if the canner is still maintaining pressure, the contents are safe. I have found nothing ascertaining the same for a steam canner. Check you canner to make certain that it did not warp.

  8. Hi there..I’m kinda new to pressure canning and have always water bathed. For some reason my mind slipped and i didn’t put and lemon juice in 24 jars of salsa!! It’s been about a week since. I’ve never had anyone dying the times before..I’ve since got a pressure canner..can I pressure can these all over again or just pitch them? Thanks.

  9. Hi Conrad, it is too late to reprocess–must be within 24 hours. Did your salsa recipe include vinegar? If so, no lemon juice is needed. Typically, a tested salsa is made with a prescribed amount of tomatoes, onion, peppers, chilies, vinegar, and seasoning. If made using a tested recipe and no beans or corn were added and the proportions of low acid vegetables was correct, salsa can be safely water bathed. If you have not followed a tested recipe, then I cannot say that your salsa is safe.

  10. I followed the Ball recipe for canning tomato sauce including adding 2 tablespoons of lemon juice per quart. 3 of the 6 jars did not seal. It is still within 24 hours to reprocess. Do I need to add more lemon juice?

  11. Hi Paul, no need to add more lemon juice. Best of luck with reprocessing and hopefully getting a good seal this time..

  12. Hello, I properly canned salsa last week and mostly followed the recipe from the Ball book,the only change I made was- I didn’t put all the spicy peppers in as the salsa was already spicy enough. I didn’t adjust anything else though- now the salsa is a bit strong on the vinegar and I would like to add some tomatoes and tomato sauce and reprocess. Should I just give it a shot? I usually always follow the recipes, but I have been wanting to try something new as my salsa tends to be mild, and watery.

  13. Hi Mikki, you may add some sugar to offset the vinegar at the time of serving. Omitting the extra chilies is okay; however added more tomatoes and tomato sauce is not. Salsas must be made using a tested recipe; the risk is too great to simply add as pH and heat penetration are big factors in salsa safety. Draining off some of the liquid at the time of use is also recommended instead thickening prior to canning. If you freeze salsa, then anything goes.

  14. I was precessing my salmon jars for 100 minutes but the pressure dropped to 8 and I only had 20 minutes left. I thought I’d better start the process again to keep the steady pressure of 11 .I was worried if I had enough water in my pressure cooker so when the pressures cooker was safe to open I added more water but the lids started to seal. I will need to replace the lids but do I need to add more vinegar?

  15. Hi Marilyn, I am likely too late to answer your question as I see it came in on Saturday. So at this point, you have done what you have done. More vinegar? Was this for hard water? If so, perhaps adding a little more when you added new water would have been appropriate but if not, there might have been a little more scale on your jars. So sorry that the pressure dropped when you were so close to the end.

  16. I was water bathing my banana peppers and one of the jars fell over it did not break at all so it seemed good. But when I removed the jars from the water bath They were already sealed? I am worried I did something wrong because they sealed immediately. Are these safe to store away?

  17. Hi Tammy, it is not uncommon for jars to seal in the water bath so if they were processed correctly, they should be safe. What is important is that you had at least 1 inch of water above the top of the jars. To prevent jars from falling over, add some empty jars filled with water to take up the open space. I suggest that you use the jar that tipped over in the very near future as even though it is sealed and likely safe, it offers the most concern.

  18. Hello- i just found your forum! I am very new to pressure canning, had a siphoning issue a few months ago which discouraged me till now. I pressure canned 4 quarts of beef stew yesterday. All looks good and the jars sealed it seems. My questions are a) is it normal to smell what you have canned when you open the canner? Also the outside of the jars had a very slight residue of the stew. The remaining canning water was clean so I didn’t seem to have any siphoning this time. My other question is about the level of product in the jar. I distributed the stew ingredients among 4 jars and added boiling water. They each have a level a little more than 2 inches from the top edge of the jar. Is this level safe? Thank you so much.

  19. Hi Rosemary,
    Yes, it is normal to smell what you have canned when you open the lid. From your details, you did have some siphoning or liquid loss during processing which, of course, went into the canning water and would result in a canned meat odor. The residue on the jars indicate the same. Some siphoning is common especially with meat products. However, I am a bit confused and concerned. You mention that you canned beef stew. Did you use a tested recipe? The brief procedure you mention does not follow the guidelines of the National Center for Home Food Preservation ( unless I am missing something. If a tested recipe was used and procedure followed correctly, the contents should be safe despite the loss of liquid and shrinkage in the jar. If not, neither you or I can assume that the stew is safe.

  20. Just made Apple Jelly using a safe approved recipe from Ball. Checking within 24 hrs it appeared that the pectin did not set. Not wanting to chance it, I put the sealed jars in the fridge overnight to reprocess them today. When I opened half of the jars this morning to reprocess I found that they had in fact set. I’ve reprocessed those since I opened them but my question is this: are the jars that I didn’t reprocess ok to take out of the fridge and put on the shelf? or is it better to reprocess those also?

  21. Kate, if the apple jelly was prepared using the Ball recipe (no pectin added) and processed correctly there should be no problem putting the refrigerated jars on the shelf. No need to reprocess as the extra heating may break the delicate pectin bonds that have formed as the jelly set.

  22. Hi I recently made salsa it’s made with a venigar base but I’ve added too much sugar by accident, is there anyway I can safely reprocess to add something to cut the sugar it was made a week ago. But it’s way too sweet to enjoy and I don’t want it to go to waste

  23. Hi Shannon, from your message, I am unsure if the amount of sugar you added affects the safety of your salsa or not. Assuming it does not, it is too late to reprocess your salsa so the best suggestion is to wait until use and then add lemon or lime juice, vinegar, onions, peppers, etc to counteract the sweetness. If it is too think, tomato paste or another thickener can be added.

  24. I just canned quarts of chicken breast. I cleaned and sealed and de-bubbled each jar. No liquid was added. I got to my last jar and it was less than 3/4 full with chicken, I processed it anyway, ( did not have any pint jars at time). Processed for full 90 minutes. All jars have sealed and look good. My last jar, the meat shrunk to about half full with the meat, liquid is above meat ibn jar. The jar is sealed, but is that to much open space in jar to be shelf stable? I have since put the jar in fridge (within the 24 hour time frame) because I wasn’t sure on safety. Now I’m not sure it is even safe at this point, someone mentioned there was only a 2 hour window to use, reprocess or refrigerate. Again, the jar is sealed.. Would love some expert advice. Thank you

  25. Hi Terri,
    Thank you for reaching out to AnswerLine. If you processed your chicken per USDA or NCFHP guidelines and jars are sealed, your chicken is safe. Included is the jar that was short. Further, by refrigerating it quickly, you can feel assured. It is now best to use it as soon as convenient. When there is a mishap in canning, action needs to be taken in the first 24 hours or as soon as the jars have cooled sufficiently to handle. It is possible that when you use the chicken in that jar, it may have a consistency (food quality) slightly different than the other jars.

  26. Just finished pressure cannon quarts and pints of venison. The book said 75 minutes for pints at 10lb and 90 min for quarts at 10lb of pressure. Somehow in the process my timers got mixed up and the pints were processed for 90 and the quarts for 75min… please help. How do I deal with the under processed quarts.

  27. Hi Lorrie, thank you for reaching out to AnswerLine. The pints processed at 90 minutes are overprocessed but are safe; expect to find the venison softer than usual. The quarts are underprocessed. If you are still within 24 hours of processing, they can be reprocessed starting from the beginning; reprocessing will result in over-cooked meat but will be safe. It is also possible to remove the venison from the jar and freeze in appropriate containers.

  28. Hi! I made Nanking Cherry jelly in July and I noticed my jelly has changed to a pretty darker red. Is this normal? Also I did not add lemon juice, should I have for this type of cherry? How do I check to make sure this product is still safe?

  29. Hi Sandy, this is a second reply to your query. I trust that you are getting them.
    Hi Sandy,
    It is quite common for fruits to darken over time. There are a number of factors that contribute to this phenomenon. Check out to learn more about the various factors that contribute to darkening. Bottom line is that most forms of mild darkening or browning do not impact the safety of your jelly. As long as a tested recipe was used and followed carefully, the seal is good, mold is not growing on the jelly, and there is no bubbling when the jar is opened, it is okay. Lemon juice may help with darkening. For best quality, keep your canned goods out of direct light and in a place between 50 and 70 degrees F.

  30. We canned some cranberries for juice yesterday. We forgot to dissolve the sugar before canning, but they all sealed with the sugar on the bottom. Will the sugar eventually dissolve into the liquid?

  31. Hello,
    I pressure canned ponys of venison with a tested recipe for 75 min. The jars had a lot of siphoning, there is only about 2″ of fluid in 2 of the jars. They did seal. I put them in the fridge just in case, but I see a lot of posts online saying having fluid less than 50% in the jar means you have to use the meat in 2-3 days. Other posts say if it was processed correctly the meat may discolor or dry but it is still safe to eat. Which is true?

  32. Hi! New to canning here. Yesterday I made salsa using the Mrs. Wages recipe plus added a few extra jalapeños for extra spice. I think I may have not left enough headspace and most of my jars are bubbly. I water bathed them for 40 minutes which is what it called for and they all sealed except one- I put the one that didn’t seal in my fridge to eat now but are the rest of them safe? They sealed but have bubbles in them.

  33. Hmmm … just processed mincemeat (with meat). It processed for the correct amount of time at the correct pressure, but when I opened the canner I noticed some liquid fat in the canning water. This means some of the contents were forced out between the lid and the jar, and likely left a very thin layer of fat and possibly sugar behind.

    It called for an inch of headspace. I probably cut it pretty close. I grew up canning vegetables. It might have been closer to 3/4″.

    Frankly even with more headspace it’s unclear to me that some of the liquid contents wouldn’t be forced out.

    I kind of hate to re-process as the fruit has already cooked a LOT, but … I will say this was a lot of effort and expense.

    I suppose I could freeze in vacuum sealed bags.

  34. Hi Phil, Thank you for reaching out to AnswerLine. If liquid is lost during processing (siphoning), it does not cause the food to spoil, but the food above the liquid may darken and dry. Having said that, do check the jars in storage as sometimes a jar can unseal months after it was canned due to the food particles or grease between the sealing compound and the rim of the jar. For more info on siphoning, see:

  35. Hi Brittney, thank you for reaching out to AnswerLine. To begin, it is imperative that you follow a tested recipe EXACTLY when you are canning food. This means that you do not add additional ingredients and you get the head space correct. Jalapenos are low in acid, so by adding extra, you may have changed the pH as tested for safety by Mrs. Wages.
    Regarding the bubbles, there are two kinds of bubbles one may find in canned foods–bubbles due to air and bubbles due to fermentation or spoilage. Did you remove the air from your salsa before applying the lid? The reason we remove air bubbles from jars before canning is that if there’s too much air in the jar, it can interfere with the jar’s ability to drive out the extra air in the top and develop a good seal. Additionally, too much air space and much of the canned product finds itself sticking out of the brine/syrup/canning liquid, which can lead to discoloration and the development of off-flavors (this is the worst-case scenario though, and typically only happens if you wait a long time to use that item). Sometimes it’s impossible to remove all the air bubbles. The goal is to do your very best at bubbling each jar before wiping the rim and putting the lid on.
    If the bubbles are moving or look like bubbles in a soda, this could indicate the presence of harmful bacteria or gases produced by spoilage. Foods exhibiting these kinds of bubbles should be discarded.

    As long as your jar sealed, you are okay. I find that the best way to check your seal is to remove the ring and elevate the jar holding onto the lid. A good seal means that it will hold fast.

  36. Hi Kasey, Thank you for reaching out to AnswerLine. If liquid is lost during processing (siphoning), it does not cause the food to spoil, but the food above the liquid may darken and dry. You were right to refrigerate the jars with 50% loss and we would suggest that you use it relatively soon. Do check the jars in storage as sometimes a jar can unseal months after it was canned due to the food particles or grease between the sealing compound and the rim of the jar. For more info on siphoning, see:
    Simply Canning gives some guidance on cause and reduction of siphoning:

  37. Hi Bernadette, thank you for reaching out to AnswerLine. The undissolved sugar may or may not dissolve into the liquid. In either case, it should not affect the safety of the cranberry juice as juice can be canned without the use of any sugar. More importantly, I hope you have processed the juice correctly (using a tested recipe) for safely storing on the shelf.

  38. I canned Beef Stroganoff using the Ball Recipe. Processed for the correct time, debubbled, wiped the lids before putting the lid on fingertip tight, followed the proper pressure canning procedures.

    At first all the cans sealed. Now the seals are releasing (2 to 5 days after I canned). I caught the first seal that released 2 days after I canned it. It was sealed on day 2 because that is when I washed the jar and removed the screw lid. The next day (day 3) I noticed the first one lost its seal. I put it in the fridge immediately but have not consumed it. Then on day 4 I noticed another jar that lost its seal. I am disposing of this jar. Since I have lost 2 jars to the seal releasing I have put the rest of the jars in the fridge and they have remain sealed (now they are day 6).

    Is it safe to consume the first jar that lost the seal?

    Is it safe to consume the rest of the jars that remain sealed and are in the fridge? Can I remove the contents are freeze it?

    Thanks for your advice.

  39. Hi Yvonne, Thank you for reaching out to AnswerLine. I am sorry you have having a false seal experience. A false seal is basically anytime a lid doesn’t remain securely stuck to the jar as time goes on. Lids loosen because there’s microbial action happening to build pressure and pop the lid, or the lid wasn’t securely sealed during processing for whatever reason. In any case, a false seal is one that seems fine at first but fails later on. A false seal is due to several different factors. The most common is jar rims which are not clean. YOu don’t mention the wiping of the jars rims prior to placing the flat lid. If you did wiped the rims, it can still happen and is not uncommon when meat products are prepared; if even a small amount of grease or food from the jar escapes with the steam and settles on the jar rim, that is enough to cause a false seal. I would not recommend that you use the contents of the jars that have released their lids. Even if they were closed at the time you washed the jars, the lids was not truly secure subjecting the food inside of the jar to potential microbial growth. If the jars in the refrigerator still have secure, intact lids, you can freeze the contents. I would advise that you remove the contents of the jars and freeze in freezer safe containers rather than putting the jars straight in the freezer as you may experience jar breakage when the food expands.

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