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!
Thanks so much for posting pictures with this blog post! I did my first tomatoes yesterday. I lost liquid and the tomatoes are floating. So, I’m not worried about that.
What my question is though, the tomatoes are floating pretty high and I think they are touching the lid, which concerns me because of the BPA in the lids, which is the whole reason I wanted to do my own in the first place….
Is there anything I can do about this? Or, should I re-process them with a tighter pack?
Thanks so much!
Oops, I just removed the jar rings and the tomatoes are not touching the top and the seal is great! So please disregard! Thanks so much!
Can you please expand on “slower cooling process”?
Though my siphoning experience is minimal, I’d like to imprint the correct process. Anything I should add or change to the steps?
-Tighten rings till they just begin to have resistance, then add a quarter turn.
Leave the jars in the water 5 minutes after processing time and move to a towel to cool out of drafts.
This is my first year of canning and am loving it. Due so much to the information you provide on this site with all the facts needed in an easy to understand dialog and good photos. Thanks so much! Glad to have found you.
Hey Lovely-
Miss Rosie goes through a *ton* of ketchup, so this year I though I’d do my own to cut her sugar intake, as the sugar-free stuff in the store is pricey. The Ball recipe has a cup for 4 pints, can I cut the sugar safely? If not, do you have a low or no sugar ketchup recipe? Thanks!!
The other day I pressure canned beef stew for the first time. I brought the water to a boil, added the jars, and made sure there was water over the jars like the water bath method. Later I realized that I had too much water in the canner. I had processed under pressure for the recommedned time, but with too much water and siphoning, are they safe?
If you got to the right pressure and processed for the right amount of time AFTER coming up to pressure and the jars are tightly sealed, they should be safe. However, I’ll bet it took forever to get up to pressure, so it might be a tad overcooked. It’ll probably taste okay but your veggies might be a little mushier.
A little about the science… Pressure canning raises the boiling point of water from 212 to around 240 degrees. That’s the temperature at which the low-acid nasties (namely, botulism spores) die. Normally, you just need enough water to create steam, which creates pressure, which raises the boiling point of the liquid part of the food itself to 240. Since you used a mostly full pot of water, you had to get the food AND all that the water up to 240.
I just looked at a web site that said it was never save to store pickled garlic. It said that I need to freeze it, or refrigerate it after hot water or pressure canning. Other sites, and my Ball book, say to store it in a cool dark place.
I can switch gears and put it in the food dehydrator, but I really want to try pickled garlic. How can I make “Killer” garlic without it becoming “Killer” garlic?
I’m not Marisa but…you can’t can plain garlic put you can safely can pickled garlic. You can’t go wrong following the Ball book.
I’m canning Pickled Garlic for the first time ( I harvested 35 pounds and need to do something with it). My Ball Canning book calls for dried oregano. Can I substitute fresh rosemary and/or fresh Bay leaf?
Thank you! I canned tomatoes for the first time two weeks ago and all four jars are floaters. I’m glad it’s normal and not a big deal.
Also, it took a lot more tomatoes than I expected it would. I have to go back and buy another case or two of tomatoes. 🙂
Thanks! I’ve never canned tomatoes before, but I can tell you that all of those things would bother me if I hadn’t read this article. Sometimes it’s nice to know when not to freak out.
i put up 6 quarts of tomatoes today and since they were heirloom types i didn’t peel or core them…husband was having fits! now i have proof that they aren’t ruined…:) it seems such a bother to peel them and i just didn’t want to
My Ball canning book said to put 1/2 tsp of citric acid into each quart. I found citric acid in a brewing store. Is this the same as the stuff I should use during canning?
Yep, same stuff!
Perfect timing for me, too. I just started canning this year and have had no issues with multiple batches of jam, but I tried salsa (4 pints), and only one sealed. All of them siphoned and separated. I think I’m just going to freeze the other three and use it in cooking later rather than just with chips.
I honestly don’t know what went so terribly wrong– I bubbled and wiped the rims well. I know that one jar fell over during processing, so perhaps that was part of it, but I’m still miffed at the other two. Could my rings have been too loose? They were fingertip tight, just like my jam.
Last Sunday I put up a bunch of tomatoes, however, some did not seal. They have been in my fridge ever since.
Is it possible to reprocess them?
I won’t be able to get to then until this weekend (I am sick). Do you think they’ll turn out OK? I was planning to have them come to room temp before I put them in newly cleaned/sanitized jars, then proceeding as usual.
I’ve heard of people preparing crushed tomatoes for water-bath canning using a food mill in a way that requires no peeling or seeding… I’m very interested in this! Any advice? Do I cook the tomatoes first? I’ve only canned whole tomatoes before… any processing differences when they’re crushed? Thanks!
This actually answers some of the questions I’ve had this week as I’ve been canning whole tomatoes. I have canned them several times before, but sometimes things turn out a little differently as you mentioned. Thanks for the info, very helpful!
Opinions on peeling/seeding? I see that nearly all recipes call for tomatoes to be seeded and/or peeled, but I’m wondering if there is any downside to leaving it all in and then pureeing with an immersion blender, or something like that?
@ jamie – this blog is awesome, but if you’re looking for a comprehensive canning guide, i would check out this link – http://www.uga.edu/nchfp/publications/publications_usda.html
Thank you so much for this post. I am teaching myself to can ,Have a a few problems, and no one to talk to about them . Where are all the recipes for everything on the table? It is hard to know which recipes are tried and true. I am in Florida and my area doesn’t have a place to go to when in doubt. So I go to the internet. I only wish that there was a site that covers all canning need as you did in this post. And when you have a question there’s a button to post a question. I’ve done carrots and they turned out to mushy. I’am in Florida and sometimes I think the processing time or the pressure cooking is too much because the stuff seems to be over cooked. My manual said go by recipe. Its confusing . Thank you so much for your time and effort in this site.
My only question is WHERE DO YOU PUT ALL THIS STUFF? I live in a 2bedroom apt and not much storage space.
This was really helpful, especially since you included the photo of the jars with the differences. Thanks!!
I’m SO GLAD you posted this particular post today because I canned a whole bunch of crushed tomatoes the other day–in the pressure canner–with tattler lids as you have, and ended-up with over 2 inches of headspace after siphoning (again, just like your photo). I knew they’d still be safe to eat as long as they were sealed, but I was afraid the exposed tomatoes at the top would end-up getting mushy and/or brown.
Against my better judgment, I opened them all, added hot liquid, cleaned the rims and lids, re-warmed the jars, and re-processed. About half the jars worked correctly this time but 2 or 3 siphoned heavily AGAIN and one didn’t re-seal (and it’s now sitting in the fridge…guess it’s getting used for Friday’s pizza night).
I’m starting to think it’s the tattler lids with their “loosen the band 1/4 turn” rule. I’m curious what your thoughts are. I’ve been using them for soups for awhile now and have had off and on problems with siphoning–particularly with densely packed soups like bean or lentil soup.
I’m almost tempted to tighten them “finger tight” the next time I use them and hope for a good seal as an experiment.
Thoughts??
This is from Patrice Lewis’ Rural Revolution Blog when she first used her Tattler lids. She was making refried beans. Please note that the maker of Tattler lids says 1/4 INCH not 1/4 TURN. Big difference. Also the suggestion to try finger tight.
“Within half an hour, I had a reply from Brad Stieg at Tattler. “Try applying the metal bands finger tight and DON’T reverse them before processing,” he wrote. (If you remember, when using Tattler lids the rings need to be loosened a quarter-inch before processing.) “The metal bands need to be finger tight/snug, but not so tight as to prevent pressure release, hence the direction to reverse the band 1/4″. What we are finding is that we do not need to reverse the metal band, so long as we are not getting them too tight to begin with.”
A later conversation clarified this issue. Apparently a lot of canners tighten the rings on their lids before processing. And I mean TIGHTEN. Since Tattler lids need to vent a bit during canning, the instructions are to loosen the rings a quarter-inch before processing. But if the rings are merely finger-tightened – not TIGHTENED, if you know what I mean – then the quarter-inch reversal isn’t necessary.”
Hope this helps.
Thank you for the advice on acidifying tomatoes using commercially bottled lemon juice. I recently used freshly squeezed thinking it would be better, then I read your recommendation and explanation– I ran out, bought bottled lemon juice, then reprocessed the whole lot. Thank you Marisa.
two questions: must you peel tomatos for canning, & must you add lemon juice – my mom always canned & never added anything.
Conventional practice is to peel. However, I do know of people who skip that step with no negative results. You do need to add lemon juice. Tomatoes have been bred to be less acidic over time, so those that were once just fine for canning, now do not have enough acid to prevent the growth of botulism. Always acidify.
Great timing…I’m getting ready to try preserving some tomatoes for the first time! Our tomato plants are doing great! I’m going to use a recipe in Small Batch Preserving…wish me luck!
Is there a particular reason that in your picture none of the jars have the ring left on them. When I used to can peppers and tomatoes I left the rings on them even after cooling and they had popped. Just curiosity on my part.
The answer to that question is here: https://foodinjars.com.s164546.gridserver.com/arugulapesto/2010/08/canning-101-how-to-store-finished-jars/
This is so well-timed!
Last year I had some float and a little siphoning with my tomato halves. I’d briefly heard about both and figured they were all safe since they sealed and never developed any off flavors or colors.
I do have a question though. Are there any tips or tricks for quickly peeling large amounts of tomatoes?
I blanch, peel, and stuff into quart jars. I assume the tomatoes were hot, then cooled while I handled them, then were reheated during processing.
How do I avoid that?
Thank you for the informative post. I had separation when I canned my tomatoes last week but now I know it’s okay. I do have some questions after reading your post and the comments. First, in the Liquid Loss section, you write “Siphoning can be prevented by better bubbling of jars”–what do you mean by “bubbling of jars”? Second, someone commented that extra head space in jam jars will allow bacteria to form. Do all jars always need to be filled to the top with the exception of the 1/2 inch or otherwise specified headspace? Thank you for such a helpful blog.
“Bubbling of jars” is the process of removing any air bubbles from your jars before applying the lids and rings. If you allow trapped air bubbles to remain in the jars during processing, they will try and escape during cooling and will potentially take a lot of liquid with them.
Please disregard the commenter who mentioned the growth of bacteria. Headspace has nothing to do with growth of bacteria. If you process your jars correctly, all bacteria should have been killed, so the headspace doesn’t play a role there. Typically, jars are filled to either 1/4 or 1/2 inch, unless otherwise specified. Never fill jars all the way to the top, you need to have some air in the jars in order to create the vacuum seal.
My couzin told me that she does a thing called cold pack which her neighbor told her about. I’ve never heard of it. She cleanes her jars, sets them on a clean towel until ready to use, the she boils down her tomatoes and puts them into the clean jars and sets the lids and rings on ad tightenes them finger tight. She doesn’t process them in any other way. Just lets them sit and then when they ping and they are cooled, she puts them away. My question is……is this safe? I haven’t canned in years but I was always taught that you had to process anything you canned, either in a regulaar hot bat canner or a pressure canner. Would love to know the answer to this. Thank you in advance, Sharon
Yikes. It is not safe at all. Tomatoes should always be acidified and processed. If nothing else, she should be sterilizing her jars.
That is Open Kettle canning and it is not safe at all. I have a few old “family heirloom” recipes for pickles like that, and I do not use those for long term pantry storage.
Thank you so much for this! I did my first jars of whole plum tomatoes from my garden (just two pints thus far but my plants are loaded!) and had some serious loss of liquid in one of the jars. My seal was good but I was still concerned…but no longer! I’m always grateful for the useful information that I get here. Thanks so much for sharing our knowledge with all of us!
Made two batches of jelly, first muscadine and then apple. I followed everything in the instructions and they gelled fine before canning. The jars all sealed and now there is nothing but liquid in them. What is going on with this, it really has me upset.
Also, a lot of people I know – including me – are scared of pressure canning. I took a canning class but they did not cover that because even the instructor was scared of pressure cookers. I want to can vegetables and most of them require pressure canning.
Jellies can take up to a week to fully set. I recommend putting a jar into the refrigerator and see if it sets up in there. The cold will advance the setting process and give you a peek at what’s to come. I am curious how you knew the jellies were setting when they were still hot and you were filling your jars.
I did the sheeting test and temperature like we did in the class. I actually had the “jelly” form on my spoon for the muscadine jelly.
If neither set up, I have read I can use the “liquid” as a glaze or syrup. Is that correct? I hate to waste what I have.
I really wish folks wouldn’t be so afraid of pressure cookers and canners. They really aren’t the dangerous contraptions people fear them to be as long as you read the directions and understand what’s going on. In fact, they can’t really “explode.” Usually, what has happened is the safety mechanism has kicked-in (a rubber plug blows) because the user wasn’t following the directions.
I recently wrote an entire post in my own blog on the subject if you’d like to stop-by and read it. It pertains to cooking in a pressure cooker, but the same safety concerns apply with pressure canners. In fact, most pressure canners are even safer because they come with pressure gauges so you can see what’s going on inside the pot.
I *love* my pressure canner. I use it to can homemade soups, homemade marinara (for Ragu-like convenience), and even all my tomatoes because the processing time is shorter.
I agree with Justin! They are very safe nowadays and quite the time saver! Just follow manf. instructions–we pressure cook many foods now.
I have been reading about canning, i love canning, find the food very tasteful in the winter, but i beg to differ with a pressure canner not blowing up, mine did not the rubber plug either, the whole lid flew off of it straight up in the air, i will never use a pressure canner again.
This was very helpful! I might have done a silly thing… I did not cook or blanch the tomato’s before I canned them just cut them up and put them in the hot jars with the lemon juice then processed them. I was going for crushed tomatoes like you get at the store so I squished them in the jar so their own juice filled in the jar. Was that ok??
Always do your research before starting a canning project! That’s not the recommended technique for making crushed tomatoes. Here’s a good post on the subject: http://www.pickyourown.org/canning_diced_tomato.htm.
Well I though I had.. the book I was using did not say how to prep the tomato’s for canning assuming you read the whole book that talked about that part in the first chapter and it was not until after I was done that I realized that there was special prep… I was my first time doing anything other then jam and jelly so I did not know I was doing something wrong.
I’m in the middle of a batch done just like that, based on a recipe I used last year. They were fine, so I wouldn’t stress over it. I just cut them up, added salt and acidity (vinegar/lemon juice), smushed everything in, and processed in a hot water bath.
Thanks for this post, and for answering the questions I sent to you! I feel much more confident about the 25 cans of tomatoes we put up this weekend.
Great information and very reassuring. I noticed that you are using some tatler lids. I am still having trouble finessing their use for succesful seals (and getting frustrated in the process!). Any hints on using them successfully?
I’ve done well with the Tattler lids, but I think it’s been mostly dumb luck. Here’s a blog post I wrote on the topic: https://foodinjars.com.s164546.gridserver.com/arugulapesto/2010/09/canning-101-preserving-with-tattlers-reusable-lids/
Whenever I can tomatoes I end up with a scaliness on the jars after I pull them out and the jars have cooled, is this from the siphoning?
Do you experience that scaliness with other canning projects, or just with tomatoes? I find that the minerals in water can sometimes leave residue on the outside of the jars. Splash a little bit of white vinegar into your canning pot before processing in order to help prevent that. And then just wash your filled jars once they’ve cooled.
Mostly just with the tomatoes, strange. I have been using the white vinegar to clean out my canning post & the jars but I’ll try adding it first so I don’t have to clean it off. Thanks!
Except I cold pack my tomatoes and they separate.
Yes, but do you blanch them to get the skins off? That can be enough heat to lead to separation.
Question: for years, I’ve been substituting red wine vinegar for lemon juice to increase the flavor as well as the acidity. Taught that way and we’ve never been sick from canned tomatoes or sauce. From things I’ve read lately, though, I’ve come to question that process’s safety. Anyone know if there is a significant difference in acidity levels? Thanks!
You can use vinegar to acidify your tomatoes, but you have to use double the amount you would use of lemon juice. A good explanation is here: http://letspreserve.blogspot.com/2010/08/acidify-your-tomatoes-before-canning.html
Thank you so much for posting this. We had similar questions re: siphoning come up when we made some salsa and pickles (the 13 qts. of tomato sauce was fortunately okay!). Tattler says siphoning can happen when lids are too screwed down too tight during the canning process. Too much internal pressure, maybe?
Glad to know those pickles and salsa are safe to eat. I couldn’t bear to throw those jars out, but I wasn’t sure what to do with them, either. I did a Google search and asked around, but not having a name or reason for the phenomenon made finding any searching difficult.
When the lids are screwed down too tightly, the air has to work harder to escape and so will often take some of the liquid with it as it forces its way out of the jars. The presence of air bubbles can also lead to siphoning.
A friend and I are going to tackle our first tomatoes next weekend, so this post will absolutely ease my mind when some of the above inevitably happen! Thanks!
I have a question regarding canning tomatoes although pertaining to homemade ketchup, so perhaps slightly off topic. This is from a friend of mine and I didn’t know how to answer her, because I have never attempted ketchup and haven’t experienced this first hand…
“Why does my ketchup and red pepper relish darken slightly over time when it is in jars? It is still sealed and tastes fine but it looks unappealing. Am I not filling the jars far enough or should I be processing them finished jars in a hot water bath instead of filling hot jars with hot preserves and sealing them that way?”
That is a natural darkening that happens to some canned food products. It happened to my peach and apricot butters this year. Skipping the processing step has nothing to do with the darkening, though the USDA would prefer that she process her jars.
Many thanks Marisa! I’ll pass that along.
Happy canning!
zThe other night I had a jar (tomato sauce) break during canning. So a pint worht of sauce was in the canning water -will that hurt the other 3 jars that were in there canning?
Get the broken glass out of the pot as soon as it is practical. You run an increased risk of more broken jars if you leave it in there to bang around and it may also break into smaller shards. That turns clean-up into even more of a chore. However, when you’re doing a standard boiling water bath and it’s nearly done, you can let it go to completion and deal with the clean-up once the other jars are finished.
Here is my question, I canned some tomatotes a few weeks ago. I went to get a jar of them the other day for ratatolie, and they smelled “off”. But the taste was ok. Is that something to be concerned with?
Tammy, if something makes you uncomfortable, don’t eat it.
Very timely and extremely helpful! Thank you so much for taking the time to share your wisdom and experience. I just started the canning process this year and have found your blog to be a huge confidence booster. I too had siphoning and float and feel much better now knowing that all is right with world since my seals are good! I’m ready for the next batch! Thanks again!
This is so very timely! We canned our first batch of tomatoes for the year and had both tomato float and a bit of siphoning, despite being very careful to bubble our jars. Never thought that regular mouths could prevent the floating, that makes sense!
The thing about siphoning that worries me is that post-siphon, all the goop from in your jars is now in your canning bath and the next batch you pop in there on a mad canning spree. Does the bath water ever go back INTO the jars?
If the water in your canning pot is really goopy, you should dump it and start fresh.
Super helpful, thanks! One quick question about the peaches you mentioned above. If and when the whole canned peaches do discolor (due to liquid loss/ or floating), are they still safe to eat? And for how long? Great blog!!
They are still safe to eat, though they will start to lose quality over time.
From what I learned there should not be a large headspace like in this photo, as this allows bacteria to form. Isn’t it a 1/2 inch headspace for a quart jar?
When those jars went into the canner, their liquid levels were at the recommended 1/2 inch headspace. They lost liquid during processing.
Well, you already answered several of my questions, so thanks! It never occurred to me to pack the tomatoes in tightly to prevent ‘float.’
When you say siphon, does that mean the liquid actually comes out of the jars? I had a few quart jars (of tomatoes) last week that started leaking liquid right when I pulled them out of the water, but they sealed just fine.
Do you know why canned tomatoes that you buy at the store never have separation issues, even when the only ingredients listed are tomatoes and salt?
Yes, siphoning means that liquid escapes from the jar during processing or cooling. That is exactly what you experienced with your tomatoes. As far as the store bought tomatoes go, commercial processors have it down to an exact science. If there’s an error, we never see those tomatoes.
I think the answer to your question about the store bought canned tomatoes is that they have equipment that does it all in the blink of an eye.
What is the recipe for the jar’s on the left of the photo?
Those are bread and butter pickles. The recipe is in my cookbook!
Yay! I haven’t canned tomatoes, yet, but it calms my fears about the yellow beans I canned a few weeks ago that were floating and were affected by what I now know is “siphoning”. Thanks for the information!
Glad to help!
This post is so great! And just when I needed answers! I just wrote a post about my canning confusion: http://seattleseedling.com/2011/08/for-the-record-a-tale-of-my-canning-woes/
This includes learning that heirloom slicing tomatoes and paste tomatoes do not result in the same kind of sauce. I’m going to be eating spaghetti with basil “salsa”. Oh well! 🙂
I grow a variety of tomatoes and over the years I have learned how to handle the different varieties. I can the big juicy ones (heirlooms and hybrids) and freeze the Roma for making sauce during the cold winter. I take care of the tomatoes in the quickest manner when they are coming in fast and save the more elaborate recipes for cooking on cold winter days. I have just so much shelf space for canned veggies and freezer space for frozen items plus I like to have something comforting cooking away on a bitter day.
Also over the years I have learned not to fuss over how my canned goods look. I still follow the book that came with my Mirro pressure canner that I bought about 35 years ago. I’ve had it in to the extension service a few times for testing and it is still fine. I used to can for my family but now I can a smaller amount just for myself. Occasionally I use a water bath canner if I have a very small amount. I use a tall stock pot with the PC rack in the bottom. When local produce is abundant it is to your benefit to preserve it for your family and for yourself.
perfect timing! i canned my tomatoes this weekend using your guidelines, and was concerned when they separated. fortunately someone in the comments section put my mind to rest, but it is also nice to have it addressed here, thanks!