Canning 101: Tomato Float, Sauce Separation and Loss of Liquid

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Tomato canning season is here and so I’ve been getting a lot of questions from people who are canning their own tomatoes for the first time. They worry because their tomatoes are floating, their crushed tomatoes have separated or their jars have lost significant liquid in the canning process and now they’re not sure if their tomatoes are safe. Let’s take these three topics one by one and put your hearts at ease, shall we?

Tomato Float
Take a look at the jars on the left in the picture above. Those are the whole, peeled tomatoes that I canned last year. As you can see, the tomatoes are floating over a good inch of liquid and tomato sediment at the bottom of the jar. This one is absolutely no big deal.

Even the most seasoned canner is going to have some canned whole tomatoes that float. This is because there are air pockets inside those tomatoes and when you pack something with some internal trapped air in a liquid, it will float.

You can try to avoid float by using regular mouth jars (the shoulders of the jar help keep the fruit in place) and packing the jar as firmly as possible (without totally crushing the tomatoes). But really and truly, it’s no big deal.

Tomato Separation
Often, I will hear from people who are concerned because their crushed tomatoes have separated into a layer of liquid topped by a layer of solids. What happened here is that you heated your tomatoes for more than five minutes, let them cool and then heated them up again.

By doing this, you’ve broken down the pectin inside the tomatoes. In this situation, the pectin was there holding the structure of the cells together and once it goes, there’s nothing to maintain the integrity of the tomato flesh together and so pulp separates from the water.

I never worry about this one either. Just give the jar a good shake before using.

Liquid Loss
Back to the picture up at the top. Take a look at the quart jars on the right. You might notice that several of those jars lost a TON of liquid. I canned that particular batch in my pressure canner and during the cooling process, they siphoned like mad (that’s the official canning term for when liquid escapes).

Siphoning can be prevented by better bubbling of jars and a slower cooling process. However, even when you’re careful, it still happens sometimes. However, as long as your seals are good, jars with even significant liquid loss are still safe to eat.

You may experience some reduction of quality over time and when it happens to lighter colored foods (like peaches), the product that’s not submerged will begin to discolor. Put those jars at the front of the queue of jars to use and don’t worry about it.

Air Bubbles
Sometimes, you’ll preserve tomatoes and once the jars are sealed, you’ll notice that there are a few air pockets or bubbles in the finished product. As long as the lids remain sealed and those bubbles aren’t actively moving around on their own, the jars are fine. Once a jar is sealed, air pockets are only a problem if they seem to bubbling independently of you moving or tapping the jars, as that can be a sign of fermentation. Otherwise, all is well.

What other tomato questions do you guys have? Let’s hear it!

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351 Responses to Canning 101: Tomato Float, Sauce Separation and Loss of Liquid

  1. 151
    Heather H says:

    I have some canned tomatoes I’d like to use (canned this summer, but not by me). They didn’t appear to have bubbles when I picked them up, but once I sat them on the counter, I saw bubbles around the top of the liquid. I will be using the sauce in a meal that my one year old son will be eating, so I’m nervous as to whether the canned tomatoes are safe to use. Thanks in advance!

    • 151.1
      Marisa says:

      Surface bubbles aren’t an issue. It’s only trouble if the jars have been sitting still and untouched for some time and there are bubbles that are still moving.

      • Stacy says:

        I canned raw tomatoes according to the Ball canning recipe. When quartering the tomatoes I scooped out a lot of the clear gel with seeds. I packed the jars full and removed air bubbles. I pressure canned them to be safe. When they were done and I removed them from the canner (most seemed to have ‘popped or sealed already in the canner) and they were cooling on the counter, the jars were full, tomatoes on top and liquid on bottom. Pretty quickly, I noticed air bubble rising to the top of the jar. About 2 hours later, I noticed the liquid on the bottom, solid tomatoes in the middle and about an 1-2 inches of air on top. No more air bubbles are rising. Are they safe? How will I know if they are not? Thank you.

        • Marisa says:

          They are totally safe. You’ll know that they’re not safe if the seals break or if the jars have been sitting along for a while and there are actively moving bubbles rising towards the top.

          • Clarence meyer says:

            What about if you go to use a jar and open it up and the tomatoes come up over the jar and spill out and you see bubbles bubbling

            • Marisa says:

              That means that the tomatoes fermented and you shouldn’t eat them. Somehow, bacteria survived the canning process.

  2. 152
    Lee says:

    I processed 8 lbs. of tomatoes for stewed tomatoes by blanching them and peeling them first. I stored the chopped tomatoes in my pantry overnight. I think the temp was between 40-50 degree. It felt pretty cool. The next day I didn’t get to the tomatoes u til around 3pm. By that time I notice a slight off Oder and some of the solids had floated to the top while the liquid was at the bottom. Also, when I put it in the pan to boil I noitce some bubbles. Not a lot but, enough to be concerned. I pressure canned the tomatoes for 15 mins at 10 lbs. of pressure (elevation under 1000) but, I’m thinking I should throw out the whole batch. It’s not worth getting sick over. If I did use them I would boilg them out of the jar for 10-20 minutes. Anyway, my question is would the pressure canning destroy the organisms of the beginning process of fermentation? I think commercial canning equipment goes to 250 d and home canning only goes to 240 which can’t destroy everything. Just wanted some other canners opinions. I do know the saying…when in doubt throw it out. lol

    • 152.1
      Marisa says:

      The pressure canning should have killed off any fermentation process. I don’t think these tomatoes will make you sick, but they may have developed some off flavors during their room temperature rest.

  3. 153
    Dominick says:

    Hi Marisa,

    Great article. My father is a seasoned tomato canner and has been for more than 50 years. He re-uses old jars from bought tomatoes, jams, jellies etc. Some top the jars he has used over and over for 10+ years and he’s never had a problem. This year I decided to join in and canned my own with his help. We water bath as my dad has always done.

    Here is the problem. I bought 200 brand new preserving jars and the supplier told me they were fine for what I was doing. So we sealed all the jars (we are burley men so I know we did them up tight!) We boiled them for about 1.5hrs And when we pulled them from the 44 gallon drum the old trusty jars were perfect…but the new jars were not so much. Out of the 200 new jars, more than half had filled with water and the lids had become loose. Even the good batch had slightly loose lids but not enough to let water in. I tightened up all of the lids on all 200 jars and the ones that had let water in have now expanded (lids not the jars) and are now sealed very tight. I have two questions. Is the purpose of water bathing to remove the air from the jar and making the jar airtight therefore preserving tomatoes? Now that water has got into the jars, they clearly weren’t airtight so does this mean there is a good chance the tomatoes will go rancid? I also have some of the jars that have a milky white looking substance at the bottom of the jar (on the inside of course). Would love to hear your take on this incident. We worked so hard to preserve 300 jars and now I’m really disappointed.

    • 153.1
      Jess Evans says:

      HI Dominick, I see Marisa didn’t have a chance to reply so I wanted to try to help you. I think ew need more information before we can try to answer your questions.

      First, I am concerned that the jars ‘filled with water’. There should only be about a half inch of head space (empty space) at the top of the jar after you fill it with product. If you are using a raw pack method, you need to fill the space around the fruit with water or tomato juice before you put the lids on.

      Second, whether you are using the two-piece lid system (a band and a lid) or a lug lid designed with a water-bath sealant, you should not crank the lids down tight. They should just be closed, not tightened (sometimes called fingertip tight.) This is because during the water bath the air in the headpace expands and escapes from the jar. Then when the jars cool, the air in the headspace contracts and pulls the lid down tight, creating an indentation in the plastisol sealant on the inside of the lid where it is pressed against the jar rim. This creates the seal. If the jar is too tight when it goes in the bath, the air can’t escape and the jars won’t seal properly.

      Someting to mention is that it is fine to re-use canning jars but you have to use a new lid each time so you have a fresh plastisol seal.

      Once you take the jars out of the bath, do NOT tighten the lids or otherwise mess with them. You risk breaking the seal. If you are using two-piece lids it is ok at this point to gently remove the bands, leaving the lids in place.

      When the lid is sealed properly, you can tell because the button is depressed. If the button pops up the jar is not sterile.

      If the white cloudy material appeared in the jars while they were in the canner, I can only guess. If it appeared later, it is probably mold and they should be discarded.

      One thing to mention, it is important to add a little citric acid into the bottom of each jar of tomatoes because some tomatoes are not acidic enough to keep botulism from growing, and the hot water bath isn’t hot enough to kill botulism. See this FDA page: http://nchfp.uga.edu/how/can_03/tomato_intro.html

      It has been a while since you asked so hopefully you already figured out what to do. In the future, if your jars don’t seal properly, you can put new clean lids and bands on them and re-process them. Do this the same day before the product has a chance to cool down or to spoil.

  4. 154
    Sue says:

    Hi Marisa,
    Thanks for the great information. I found your pictures of canned products especially helpful as mine were looking exactly the same. So much easier when great pics explain it all!
    Glad to know all my hard work isn’t going to result in throwing them out to the chickens.
    Cheers
    Sue – Townsville Austrailia

  5. 155
    Susie says:

    I canned some tomatoes in 2013 and the seal on the jar is still good. Noticed in one jar that some the tomato seeds are now dark, they weren’t when I canned them. That did not occur with my other jars, have the tomatoes gone bad somehow?

  6. 156
    Dani says:

    Very helpful article. Thank you. I have a question. I have been told not to transport my jars of tomatoes for several days after canning. For years I have carefully placed the jars in crates and not moved them from the kitchen into the cellar for several days. Is this a myth or true? This year I have an opportunity to use an industrial kitchen for canning, but am concerned about transporting them in my vehicle while they are still warm.

    • 156.1
      Marisa says:

      That’s a myth. You just don’t want to move them while they’re hot and the seals are still forming. Once the seals have formed and the lids have cooled a bit, they are fine to transport.

  7. 157
    Mike Fuller says:

    We did a standard 7-jar canning of tomatoes and were 1″ shy of filling the last quart jar. We processed it the same as the others and it sealed with a click just perfectly. Normally we put anything that’s “out-of-processing-limits” in the fridge – and use it first – to eliminate the possibility of spoilage but this time I want to question why, if the seal made and the process was followed in every other respect, the air gap rules don’t allow for this much air gap. What are the risks of leaving too much air in the jar? Thank you in advance.

    • 157.1
      Marisa says:

      There are a couple issues around leaving too much headspace. The first is that during the processing time, a jar typically vents all of its air. This venting voids the jar of air that can carry microorganisms and thus helps prevent spoilage and possible surface oxidation during storage. This venting is also what leads to the formation of the seal during the cooling phase. If you process a jar with too much headspace, the risk of spoilage and oxidation increases.

      Second is the fact that if you have too much headspace in a jar, there is a possibility that it will float in the canning pot. Admittedly, this only happens when you’ve left far more headspace than you did. But floating jars often end up breaking during the canning process, as the boiling water buffets them around the pot.

      Since you only have a bit more headspace than is called for, I think your jar will probably be fine and entirely shelf stable for some time to come!

  8. 158
    Gayle says:

    Canned tomatoes in their own juices. I water bathed some for 45 minutes and pressure canned some for 25 minutes. I have since read that if I cold pack slices in jars in their own juices I should water bath for 85 minutes. Only read this in one article. Is it ok that I only processed for 45 minutes in water bath canner?

    • 158.1
      Marisa says:

      The correct processing time for tomatoes packed in their own juices and canned in a water bath is 85 minutes. The tomatoes that you processed for 45 minutes will have a higher risk of spoilage. Here’s the official timing reference: http://nchfp.uga.edu/how/can_03/tomato_without_liquid.html

      • Sarah says:

        So, The jars that I just canned with tomatoes had about half natural tomato juices and half water. I did also add lemon juice according to that same website. As long as it’s not all natural juices, am I fine boiling for 45 minutes?

        • Marisa says:

          Yes. You’re really just trying to break up the density of the tomatoes with the water. There’s always a little bit of natural tomato juice that gets in there.

  9. 159
    Lorna Spaulding says:

    I’m in the process of making tomato juice with a juicer and the tomato and water are separating on raw juice.

  10. 160
    Shawn says:

    I have a question for anyone who can answer for me. I am a new canner and I am learning so please be nice and remember when you were once new.
    Here is my question. I was told it was okay to can my tomatoes in a regular pot. She said she has done it for years this way. I did this, I have been reading online and see this is not the best thing to do. I need to know if the jars I have already done are okay to use or if I should toss them? They all have sealed. Very limited amount of bubbles, color looks great. How do I know if they are okay to eat? I have been checking them daily to make sure they have stayed sealed. Also will mention I did add salt and lemon and processed correct amount of time.
    Any suggestions would be greatly appreciated.
    I now understand this is wrong, But is it so wrong I ruined 12 quarts of tomatoes.
    Thank you

    • 160.1
      Marisa says:

      Tell me more about what you did. You can certainly use a regular pot as a boiling water bath canner. Were the jars fully submerged in the water? And how long did you process the jars?

  11. 161
    Julie says:

    I’m preparing to can some san marzano and other plum tomatoes from my garden in a couple of weeks. I have a Wolf steam convection oven with a setting for preserving jam that I’ve used for jams and chutneys and am wondering if I can use this setting (it steams for 1/2 hour) to successfully process tomatoes. If it’s a matter of the length of time, I could always run the program twice. Do you have any thoughts on whether this ‘steam’ method is safe?

  12. 162
    Donna Weis says:

    I just removed my jars of tomatoes that I water bathed for 85 minutes. I noticed that a little tomato escaped from the jars because its’ on the cloth they are cooling on. I’m absolutely certain I cleaned the rim of the jar prior to placing on the scalded lid/rings. There is a little tomato residue in the pot of water I used to process them. is this normal as long as they seal when cooling?

    • 162.1
      Marisa says:

      That is totally normal. You simply experienced the loss of liquid mentioned in this post.

    • 162.2
      carol ross says:

      I have canned 32 jars of tomatoes now. And only 6 have sealed.
      I have followed the directions perfectly.
      The reason that so many jars have not sealed, is because the tomatoes boil out of the jar into the water bath.
      I have no idea how to prevent this from happening.
      So frustrating. 🙁

      • Marisa says:

        Carol, it sounds like perhaps you’re not removing the air bubbles from the jars thoroughly enough. What technique or recipe are you following?

  13. 163
    Paula B. says:

    Can you reuse lids as long as they aren’t damaged or pierced? I was worried that they wouldn’t seal more than one time.

    • 163.1
      Marisa says:

      You are never supposed to reuse lids. The sealing compound doesn’t have the strength and flexibility to give you a good seal more than once.

  14. 164
    Trish says:

    I just pressure canned a bushel of tomatoes 2 days ago and just removed the band’s. I noticed the rims of all my jars have tomatoes residue on them which I’m sure means there’s tomato sauce between the lid and rim of the jar. The jars are sealed tight though. No lids are clicking. Are they still good even though it’s obvious tomato sauce has managed to escape?

    • 164.1
      Marisa says:

      That is fine. As I mentioned in this post, some liquid loss during canning is totally normal, provided that the jars still seal.

  15. 165
    Lily says:

    I canned whole tomatoes raw packed in water for the first time and had a question on color. I processed the tomatoes (straight from the garden!) for 45 minutes and added lemon juice before processing. The color of my tomatoes is not the beautiful deep red color, but rather a orangey/ light red color. I also recently canned salsa with similar results in color. Are the tomatoes safe? And is there are reason they did not become deep red while processing?

    • 165.1
      Marisa says:

      There’s nothing about the canning process that should turn your tomatoes red. They are whatever color they are. As long as you added the proper amount of acid and processed them for the correct amount of time, they are safe.

  16. 166
    Cathy says:

    I processed my tomatoes in their own juice and misunderstood the timing thinking the raw pack with water was the time to use so I only processed for 45 to 50 minutes. They sealed okay so are they okay to use?

    • 166.1
      Marisa says:

      As long as you put the proper amount of acid in them, they’re not going to become unsafe. The shorter processing time does mean that they have a higher risk of spoilage, though.

  17. 167

    Can i cook the tomatoes one day and reheat and can the next?

    • 167.1
      Marisa says:

      It’s not a great idea. When you heat, cool, and then heat tomatoes, you break down their pectin and they end up separating. You get jars that are half pulp and half water when you do it that way.

  18. 168
    Brenda says:

    I have never had this happen to me befour,I did a water bath added my salt lemon juice took out air bubbles clean rims,when they were done I ended up with about an inch of white at the bottom of my canned tomatoe jar,
    Is this ok why would it do that? please help I don’t want to get sick.

  19. 169
    Carol Habig says:

    Is there a danger in overprocessing tomato sauce? My gas grill burner went out during processing so I processed them 85 minutes after return to boiling.

  20. 170
    Pam Curry says:

    Lids. Poping after 9 days of canning what Can Can do to fix the problem

    • 170.1
      Marisa says:

      If the seals went bad after nine days, you’re probably experiencing some spoilage. There’s really nothing you can do at this point.

  21. 171
    juicygirls says:

    HI I have a questions. I just started canning this month with our garden tomatoes. Everything online is stressing me out about bacteria and botulisum. My neighbor taught me to can stewed tomoatoes (diced tomatoes, green peppers, onions and salt with some lemon juice) then process in a water bath. Theyturned out lovely.. water on the bottom a few inches and tomatoes all up to the lid nicely packed. After reading online and getting worried my sis in law showed me how to use a pressure cooker. They tomatoes did not turn out the same at all… they all have a huge headspace gap with some water on the bottom and some just having no liquid at all at the top. Should I be worried? Also, is it ok to do water bath for tomatoes because it is way easier and I prefer it but worry that it needs teh pressure cooking?? please advise thanks

  22. 172
    Susan says:

    So appreciating your generosity with answering so many questions! Here’s mine: every time I’ve canned tomatoes, I’ve ended up with about 1.5-2 inches of liquid at the bottom of the jar. I understand that’s not a problem, but I see your photos and it’s clearly possible to end up with a jar that’s perhaps MORE full of tomatoes. Is there anything I can do to try to eliminate some of the air bubbles in advance? Looking at the 3 lovely pints I did last night, I’m wishing there was one more tomato in each jar–but last night, as I filled the jars, they really seemed stuff to the brim with tomatoes. ANy advice? Or should I just live with my 2 inch floaters?

  23. 173
    Carolyn Roberson says:

    First time to can tomatoes using water bath. I packed tomatoes(uncooked) added salt& lemon juice and brought to a boil then boiled for 20 mins. Found this site and saw where they were cooked much longer. Mine are sealed and beautiful – do you think they are okay?

  24. 174
    Debbi Pawson says:

    Can you tell me, I canned some salsa last year and do not like the consistency, the taste is good. Can I empty those jars into a pan and add more chunks of tomatoes and reprocess?

    • 174.1
      Marisa says:

      Salsas are carefully balanced for safety. It would not be safe to add additional tomato at this point. You could open the salsa, cook it down, and then recan it. But I’d probably just drain or puree each jar upon opening, rather than remake the whole batch.

  25. 175
    Vera says:

    I peeled tomatoes and put them in a stainless steel pot (ordinary stainless not 18/10). After 1 or 2 hrs i transferred them to another container as was chopping them. When all the tomatoes were transferred there was about 1 or 2 inches liquid on the bottom of stainless steel pan. Half an hour later when i took the pan to wash i noticed the tomato water had turned into a gelatine like substance. I do not know what that is., Are those tomatoes safe to can nd eat?

  26. 176
    Marlene L Petrovich says:

    I have been canning tomatoes for 45 years and have never had a problem. I cut and put thru my kitchen aid juicer, cook tomatoes and place in hot sterile jars add one teaspoon of kosher salt place lids and process for 30 miniutes. Last year because of the acid concern I added citric acid. It tasted terrible and I through out my meatballs and sauce. This year I did my old way and now I am worried. Could I place the seal processed jars in the refrigerator not enough space to place in the freezer?

  27. 177
    wayne says:

    Hi i have just started to learn how to do tomatoes the video i watch told me to peel cut in half and water bath for 50 minutes in jars . It sealed but there are alot of bubbles that move freely. Plz help are good to store for winter use ?

  28. 178
    Joe says:

    Thank you for a wonderful page Marissa. While canning some Roma tomatoes, I had to stop canning for about four hours. The jars had been washed in the dishwasher and the crushed tomatoes were in a large pot on the stove. When I returned, I reheated the crushed tomatoes on the stovetop and brought them back to a boil, but forgot to consider that the jars in the dishwasher had cooled. Dishwasher was not opened, so no exposure, but I canned directly into room temp but sterile jars. Cleaned the rims, added lemon juice concentrate, and water bath processed for required time. Will everything be OK even though the jars were room temp and I had to reheat the tomatoes? Thank you

    • 178.1
      Marisa says:

      As long as the jars didn’t crack, all is well. Your tomatoes may end up separating a little since you heated, cooled, and heated them again. But as long as the processing step went off without a hitch, all is well.

  29. 179
    Michelle Pearson says:

    I have just canned salsa for the first time and my head is ovèr a 1/2 inch. The jars did seal. Is the salsa still safe to eat?

  30. 180
    Kim says:

    I peeled and quartered about 30 lbs of tomatoes Monday, ran out of time so I refrigerated them in a large, sealed bowl. It’s Wednesday…is it safe to raw pack and process them or did I miss my chance?

  31. 181
    Becky says:

    I have a question, I made 7 quarts of tomato sauce last night, woke up and realized I forgot the lemon juice! is it ok for me to open them up today, reheat the sauce and then reprocess them after adding the lemon juice?

  32. 182
    Alma says:

    I have a question, I made some chili sauce last week and now I am seeing these little white looking “spores”? on the side of the jars.
    not sure if that is what it is. I am just worried because I don’t know if it is spoiled.

  33. 183
    Jennifer says:

    I canned tomatoes using the hot water bath method, the lids on each jar are pushed up in the middle as if there is too much pressure built up in the jar. What would have caused this?

    • 183.1
      Marisa says:

      If the lids are pushed up in the middle rather than being concave, the contents of the jars are spoiling and should be discarded.

  34. 184
    kate says:

    I canned a bushel of tomatoes a week ago, checked the lids the next day and reprocessed the few that weren’t sealed, as I’ve done for years. Today, my husband heard a tiny hissing sound walking past the pantry, and noticed some jars (while still appearing to be sealed) were leaking. 🙁 I have gone through and rechecked all of them to make sure the remainder have a firm seal, but am unsure about the safety of the others. Can I stick in the fridge for quick consumption or make them into a sauce to can? And do I need to do anything with the jars that seem ok? Obviously, I don’t want to do something stupid, but I hate having to pitch anything that I could salvage.

    • 184.1
      Marisa says:

      If the jars are leaking, they are spoiling and shouldn’t eaten. I’m not sure what you should do with the rest of the batch besides keep an eye on them.

  35. 185
    Kathy Babb says:

    Just canned 38 quart of spaghetti sauce and part of them have pinkish bubbles on top when I took them out of canner. I’ve never seen this before. Lids are sealed. Wouldn’t think they start spoiling before I set them on the counter. What do you think?

  36. 186
    Travis says:

    I have some canned roasted garlic tomato sauce that I canned two years ago. I’ve opened 4 of the 8 jars and all so far have very small amount of orange foam on the top. Not a lot but a little bit on all of them? Is this normal and / or safe to eat still? Thanks!

    • 186.1
      Marisa says:

      Was it properly acidified? Were you following a recipe from a tested source? Did you can it for the proper amount of time? Then it’s probably fine.

  37. 187
    Vicki Jones says:

    Marisa–I hate to admit that I did this but here goes–I had done everything your supposed to do to can cold pack tomatoes. I had rapid boiled for 85 minutes (it was late in the evening) thought I would wait a couple of minutes before lifting my rack to sit my canned tomatoes on the edge of the water bath pot. Well as you probably can guess I fell asleep and the tomatoes was still completely submerged still in the water bath pot. They was cool to the touch had apparently been submerged for 6 to 7 hours. All the can tomatoes are sealed. Are these going to be good to eat? Has anyone ever done this before. Help I’m really concerned about this.

  38. 188
    Amy Miska says:

    Hi: I made tomato sauce at the end of September. When I opened the jar at the bottom was a milky substance. The sauce did smell different then the other ones (not necessarily bad but very different). I threw it out. Any Idea why this happened?

    Thanks so much

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