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

August 24, 2011(updated on October 3, 2018)

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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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506 thoughts on "Canning 101: Tomato Float, Sauce Separation and Loss of Liquid"

  • I noticed on my canned whole tomatoes a thin white line on the water line inside, just on the glass not like a film.
    Should I be concerned?

  • In regards to thenthin white line I have heard its from your hardware. Just add a glug on vinegar to your canning water.

    1. It’s typically from hard water, actually. The minerals in the water separate out and adhere to the jars and pot as the water boils down.

  • I canned tomatoes and the lids expanded as if fermentation was happening. I opened one and it looked and smelled normal. Do you think it’s safe to eat these or is it best to discard?

    1. What kind of film? I can’t really determine what’s going on with your tomatoes from a brief description. If what you’re seeing gives you pause, you should not eat the tomatoes.

    1. Typically, that cloudiness comes from the small bits of pulp. However, if you’re concerned about the safety of your tomatoes, you should not eat them.

  • Is it better to have more acid or less acid if you are canning things like a salsa tomato salsa blueberry salsa and I know it calls for earth acid but if you’re adding other ingredients other than straight by that recipe should it be a higher acid level or a lower acid level if it’s a If it’s a acid product like tomatoes or blueberries thank you

    1. Higher acid content is always desirable when canning anything in a water bath canner, because botulism spores cannot germinate in high acid environments.

  • When siphoning happens, sometimes bits of tomato get into the seal, but it still seems sealed. Is it safe to eat them if there are little tomato pieces hanging from the inside of the lid?

  • I canned tomatoes. Some looked very dark right after the canning process- the seals are good. Some looked like red tomatoes. The dark ones smell OK. Can I eat them?

    1. It sounds like perhaps the oxidized a little. That’s normal and as long as you followed a tested process and the seals are good, they should be fine.

  • Hi marisa! My tomato jars have a lot of bubbles in them, almost looks soapy. I have separation because I reheated them before canning. They all sealed without issue. I’m positive it’s not soap because I boiled the jars before filling them and the pot I used to cook the tomatoes was brand new and just rinsed out. I have 18 jars of these tomatoes, help!

    1. It’s natural to have some foam in the jars. I’d let them sit for a couple of days to see if it diminishes.

  • I have some tomatoes that my mom pressure canned 15 years ago. Was going to trash today & when I opened jar, they smelled wonderful. Jar was sealed tightly. Are they safe to eat?

  • I’ve been canning tomatoes in a old Aluminum pot. For about 35 years. Me and my spouse are in our early 80s. Nothing has happened to us yet. Is it OK to hand this the spot down to my children because they are in the canning also. I’ve heard you shouldn’t cook or can Tomatoes in aluminum. But this pot has worked for us for years and years. Making salsa every year and canning tomatoes in juice. Thank you for a comment

  • I pickled cherry tomatoes the recipe called for water, white wine vinegar and white distilled vinegar I didn’t have white wine vinegar so I used bottled lime juice, the liquid looks cloudy in the jars but everything sealed , did the lime juice cause the cloudiness or tomatoes splitting? My water is filtered so it’s not from that!

    1. I bet its from the split tomatoes. I wouldn’t worry about it unless you see other signs of spoilage.

  • My tomatoes are turning red on the vine in small batches (say 4-6 at a time). As you know this is not enough to make sauce. An their counter life is finite. Can I make small batches of sauce, refrigerate, and combine then reheat to a boil once I have enough to can 4+ quarts?

    Thank you!

  • I just canned 6 quarts of tomatoes. I planned to raw pack in own juice, but I read in usda canning book that quality of tomatoes is better if the tomatoes are simmered 5 minutes and hot packed. So thats what I did. After removing from WB after waiting 5 minutes, 4 of the 6 siphoned juice. Should I just freeze?

  • While making our yearly tomatoe sauce we cut the tomatoes the day before we cooked them and when we started boiling them the day after some of the tomatoes had a white film on them. We still booked them and jarred them. Do you think they’ll be safe to eat

    1. Were they refrigerated? If not, they may have started to mold overnight. Still, they should be okay since you boiled the sauce and processed the jars.

  • Hi, I’m a newbie to canning. I wanted to make a tomato purée, using just tomatoes nothing else. I used 32oz jars with a boiling canner. I set the timer for the time indicated and turned up the heat. The problem was that the water never came to a visible boil. The water temp went as high as 200 or so for the recommended time; I even heard the ping of the lids sealing while they cooled but I’m not sure if they’re safe to use.

    1. It might be that your stove is not sufficiently powered to process canned goods. You need to achieve a rolling boil for things to be safe.

  • Hello! I canned some Romas last night, and was just taking off the rings and noticed a lot of tomato pulp had gotten up inside around the rings, and almost like it was trying to leak out where the lid meets the glass. I’ve never had this happen before. The lids are tightly on and have “popped,” so the seal worked, but are these tomatoes safe to keep canned? Thank you!

  • Using my Ball canning book, I made tomato soup that called for 2 tbls oil to saute onions garlic, and peppers. All jars sealed and while wiping them down after cooling, I noticed that there is a dark ring of liquid that looks like oil. I’ve used this recipe once before this year and checked the other jars for comparison. The other jars don’t have a dark ring at top. My first batch was thin soup, so I really cooked this 2nd batch down to thicken it. Could the color be a sign of something bad or over cooking. I will be heart broken if I ruined all this. Pls advise.

    1. If you followed the recipe as written (other than cooking it down a bit more), it should be okay. Sometimes tomato products discolor a little. It’s not typically a sign of spoilage unless there are other signs (like active bubbling or broken seals).

  • My tomatoes that have liquid on the bottom and crushed tomatoes up towards the lid I know are ok. How about the two jars I had that were crushed tomatoes on the bottom covered with liquid and the top two inches of jar have no liquid. Could have bubbled out during canning but wondered if those jars would be ok.

  • I have a white sediment in the bottom of the one jar. I have never seen this and the other jars don’t have that.
    What is this? Plus, they were separated but you answered that for me.

  • Hello Marissa,

    Last year, and this year, I have used raw pack with citrus acid for my tomatoes. And I noticed with the raw pack, I have tomatoes that have bubbles after the canning. The bubbles did not move and the tomatoes were fine. The floating – wide mouth/regular, I always get floating. Thank you for writing this column.

  • I made crushed tomatoes boiled for atleast 1 hr and added salt, it was late so I put into sterilized jars with lemon juice and kept in the fridge for 24-48 hrs before processing in a water bath.

    My tomatoes are looking separated. I’ve never had this happened. Are they still okay despite the appearance?

    Thanks so much for your help and time!


    1. This is addressed in this blog post. If you heat, cool, and then reheat tomato products, they will separate. This is not dangerous. You just broke the tomato pectin down. Use the tomatoes. They are fine.

  • So I canned a bunch of slightly blended tomatoes last week with basil and citric acid. BTW first time I used citric acid when water bathing tomatoes. At first, all of them were separated with liquid on the bottom, tomatoes on top. By the end of the day, I noticed that in some, the tomatoes were dropping and in one jar, bubbling and dropping were occurring. I unscrewed and checked that the seals were still fine. As a precaution, I took the one that had a lot of bubbly action and put it in the refrigerator as I didn’t want to waste the organic tomatoes!

    1. Active bubbling occurs when fermentation is taking place. I would be VERY surprised if your tomatoes started fermenting after less than a day out of the canning pot. It sounds to me like normal settling.

  • Thank you SO much. It was my first time canning tomatoes and when I saw the liquid on the bottom of the jar I thought “Josh Darn ” I ruined them. And all the time and effort!. You put my mind at ease and once I shook the jars they looked perfect. Thanks for giving me the confidence to do more canning.

  • Hi! I canned crushed tomatoes and water bathed them properly. They sealed well and sat on the table for a couple days. I went ti move one and jt exploded. Why?

  • Hi Marisa,
    I pureed tomatoes and did a water bath for 40mins in my sterilized jars. Upon opening the jars, the tomatoe puree has pushed to the top, and water is on the bottom. There is a small spot of white on the top of the puree, but the jars did pop when bathed, and when opening the jars the seal was tight. I am not sure if this is safe to eat

  • I canned pasta sauce. In the process sauce came over the jar .They did seal but does have sauce around the top. And have bubbles in the bottom. This has never happened before and Ive been canning for many years

    1. As long as the jars are sealed, they’re okay. I’m not sure why your sauce behaved like this, though.

    1. Did you process them half full? That’s not a great idea because they can float in the canner and break. Half full jars are also more prone to spoilage.

  • My daughter canned tomatoes this year with the same receipe we have used for years. This time she has eight jars that have a white film or residue in the middle of the jar. Looks like maybe she didn’t push the tomatoes down far enough and left an air pocket. Question is are these safe or contaminated and need to be thrown out?

    1. If they were properly acidified, processed for the proper amount of time, and the seals are good, they should be fine.

  • I have a white sediment on the bottom of the jars.
    Tomatoes were canned 14 months ago, I have used many jars and did not notice this sediment previously.
    Are they ruined?

  • The response to my question about a white sediment was not answered. I do not have float or separation. I have a white sediment, not much , but still visible.

  • I canned some tomatoes and now I don’t know if I canned them for 10 minutes or 25 will they be ok if I only pressure canned them for 10 .

    1. I would recommend that you put those jars in the fridge and use promptly. Ten minutes isn’t long enough for safety.

  • After water bath tomatoes for 85 minutes per the recipie, I put jars on towel to cool overnight. I noticed there was seepage of red tomatoe on the towel at the bottom of the jar. They all sealed but wondered if I should re can?

  • I am washing my tomatoes before cooking and I had one tomatoe that sank to the bottom while all the others stayed floating, does that mean the tomato is bad, ( I smelled it and it smelled fine?
    Thank you

  • First time making tomato sauce, I forgot to add the lemon juice. It’s just straight tomato juice. They also separated. Should I redo it and add the lemon? Can I fix the separation issue?

    1. There is no way to fix the separation. When you heat, cool, and then heat tomato products, they separate. I would recommend that you open the jars, add the lemon juice and reprocess, as tomatoes need bottled lemon juice for safety.

  • Newbie here, processed my first Tomato Meat Sauce using the directions from the Ball Canning Book following the correct pressure and time requirements. When I removed the jars I noticed a small amount of sauce in the bottom of the canning pot. All the seals are firm on the jars. Is this normal?

    1. That is normal. Often you’ll find that a small amount of product has siphoned out of the jars during the canning process. As long as the seals are good, your jars are safe.

  • I water-bathed my quart jars of tomatoes. There were only 4 quarts in the pot and one of the quarts was about half full and it was mostly tomato juice. That one sort of floated. Although the canner was as full as I could get it, the rest of the quart jars were barely-if not completely- covered with water. If everything seals, area the tomatoes safe?

    1. You can never, ever can half filled jars. They must be properly filled or the product will be unsafe because you won’t be able to remove all the air from the jars and you risk spoilage. And they need to be fully submerged. It sounds like you need a larger pot.

  • I made salsa with no vinegar. Pressure canned at 15psi for 10 minutes (altitude of 1010 ft). I had separation of the liquid which brought me to your site and this article! But when reading through the comments someone else canned for only 10 minutes and you advised not to store but to put in refrigerator.. is this my case as well? I followed the instructions I had, though it was from a source online and not a Ball book. Thanks.

    1. The National Center for Home Food Preservation does offer 10 minutes at 15psi for some tomato products, but only at 1,000 feet or under (I think you should still be okay on that front). So your salsa should be shelf stable. I do recommend that in the future, you always cross reference pressure canning instruction that you find online with the guidance from the NCHFP. Cross checks never hurt and they often help!

  • Please explain the science behind why you now must process 85 minutes when you can crushed (or quartered) tomatoes in their own juice vs. whole tomatoes packed in water only need 40-45 minutes. I have been canning for decades using 45 minutes with zero problem. I add the 2 T bottled lemon juice (Santa Cruz brand) to quarts now.


    This is the most frustrating canning I have ever done… and I used to man the canning hot line at our local AG Extension in my days as a UC Dietitian intern 50 years ago!!! I want brand names. I do not feel comfortable with the steam canner either.

    PS I have appreciated your thoughts and agree with you (from experience) regarding tomato float, etc.

    1. Crushed tomatoes only need to be processed for 45 minutes. It’s only whole peeled tomatoes that require 85 minutes. The reason there is a difference between tomatoes packed in their own juices verses packed in water is that the water reduces the density and allows the heat to penetrate the jars more rapidly. That accounts for the difference in timing.

      As far as setting up a canning rig off your stovetop, I suggest an inexpensive induction burner paired with a flat bottomed aluminum pot. Far cheaper than the Ball device and just as effective. Induction boils water incredibly quickly.

  • My husband is trying to learn how to can tomatoes. He recently canned 3 jars and did no fill the jars full, rather left 2 to 3 inches from the top. He boiled the tomatoes before jarring and all 3 sealed. Is this going to be OK?

    1. That is a lot of headspace. Part of the reason we don’t like to leave more headspace than the recipe calls for (typically somewhere in the neighborhood of 1 to 1/2 inch) is that during the canning process, the jar vents its oxygen. This helps remove microorganisms and prevents oxidation. Leaving that much headspace increases the likelihood that the jars can’t vent all their oxygen, increasing the risk of spoilage. As long as he did the canning process properly, these jars are probably okay to use in the near term, but they do have an increased risk of spoiling over time. In the future, I highly recommend following the guidelines for headspace to ensure a shelf stable product.

  • So helpful as I just canned 12 jars of packed in romas and yes, there are tomatoes above the liquid line after the hot water processing methods of 85 minutes, so o was worried, I feel much better now, thank you!

  • Hello! I steam canned halved and quartered tomatoes with tomato juice as per NCHFP, but recipe was for whole or halved tomatoes. I processed for 85 minutes in steam canner. My Harvest canner instructions says that canning times can be used interchangeably (no mention of 45 min. max. After processing time, I turned heat off snd let sit fir 5 min., as directed. There was a fair amount of siphoning but the kids all popped and appeared sealed. Will they be safe or should I throw out? Too many to put in fridge and use in short amount of time. Sorry for long post. Love this website!

  • I have tiny, rust specks on the inside of my canned crushed tomatoes. All were sealed tightly and absolutely no signs of spoilage. Have you seen this before? Safe?

  • All I want to know is my tomatoes boiled over I lost liquid. So do I replace or add water to it when I finish cooking for juice to can. Thanks
    (my fault)

    1. How much liquid did you lose? If it was a fairly small amount, I wouldn’t worry about the loss. I’d just proceed with the proper acidification per jar.

  • I heated my tomatoes that I was using to make tomato juice in my aluminum pressure canner. I also use my pressure canner to heat my juice to boiling before I put it in my hot jars. To finish is it safe to use?

    1. Aluminum pots don’t make things unsafe, but they can impart a metallic flavor to the finished product. Taste and if it seems okay, you can proceed.

  • I just noticed a jar of my crushed tomatoes didn’t seal. It’s been about 24 hours since they were canned so they’ve been out on the kitchen counter. Should I use them or discard?

  • Just finished canning tomatoes with water bath, and next day there is a sediment (black) in bottomof jar. I used quart jars with citric acid,salt sugar in correct measurements. I have never had this happen before. What could this be and are they safe. Also 1 jar has bubbles. Your help is appreciated. 38 quarts, and sediment in about half.

    1. That’s totally normal. And as long as those bubbles aren’t moving like they are carbonated, they aren’t an issue.

  • Hi Marisa, Your recipes and content are fantastic, I love following you on social media. Question – I canned salsa last night and thought I reached 1/2 headspace, looking at the jars today it looks closer to 1 inch. Will the salsa still be shelf-stable? I’m hoping to avoid reprocessing the salsa. Thank you.

    1. That’s a relatively minor issue. As long as the seals are good, they should be fine. Tomato products can siphon or settle sometimes.

  • That’s not exactly how or why tomato separation occurs. Tomatoes release an enzyme that breaks down pectin when they are cut or crushed. The way to keep separation from happening is to heat your tomatoes immediately after cutting them to kill the enzyme.

  • I am wondering if it is okay to can a half full jar of tomato salsa. I did it, along with full jars, and it sealed. Is this salsa safe to keep for several months?

    1. You never want to process jars that are half full. There is the risk of floating during processing that can lead to breakage, along with the fact that there is just too much air in the jar to fully vent during processing. You either want to quickly heat a smaller jar, or put the half full jar in the fridge to be used promptly.

  • My method for canning tomatoes is to blanch first to remove the skins, cut them in half to check for black spots and if there are I throw them out, after cutting in half I put them in a large pot to simmer for a few mins and salt them. When I fill them occasionally I will end up with the last jar not being filled all the way up to the 1/2″ to 3/4″ headspace that’s required. I have grabbed a few tomatoes and blanched them to remove the skins but instead of cooking them too I cut them in half and put them into the jar of hot tomatoes to fill it up. I figured it should be OK since raw packing is a thing but since I am pretty new to canning thought I should ask. Thanks!

    1. The issue with what you’re doing is that the jar with the raw packed tomatoes has a lower internal temperature and so will need a longer processing time to ensure that all bacteria is killed. I’d suggest that you give that last jar a little extra time in the canner. Or, mark that one to use first.

  • Do you know why the lids of homemade passata might come off during water bath cooking. We made a large batch and even had the same person put on all the lids to ensure they were the same level of tightness but had quite a few lids come off during water bath. We haven’t been able to find much information about why this might happen

    1. Were they bottles with lug lids? Those do often need to be tightened more aggressively than jars with lids/rings do. It could be that the water was boiling too vigorously and agitated the jars/bottles too much.

  • Can I use ketchup for my sloppy joe recipe it does call for addition vinegar, brown sugar,onion, I bring to simmer and water bath for 15 minutes is that to process