What is Flat Sour and How to Avoid It 

My daily dose of “education, with a dash of science, plus a smidge of pure common sense”. ❤❤ you both!!

Recently I opened a can of green beans that tasted like feet. I had no idea why since in all my years of canning I've never had that problem. Watching this reminded me that last year I had exhausted myself one day with canning and decided to just go to bed and take the jars out in the morning. It's the only time I've done that and, yep, it was with a batch of green greens. Thanks for the info! It's always good to know WHY we are doing something, not just what we should be doing.

I guess the reason that I haven't had this happen is because I'm always too excited to get the jars out, and on to the counter so I can admire my handiwork! Lol! 😊

So glad you addressed this. My first batch of canned chili was left in the canner overnight, and it definitely developed flat sour. I'd canned it trying to get my partner to stop buying and eating Hormel chili ($$ and not good for him). He was very suspicious of the taste, thinking I was poisoning him. I tasted some of it, and he was right: It tasted (to quote you) "nastyish"! I researched and found out info on flat sour and told him it wasn't going to kill him, but he still wouldn't eat it. Our dogs were the beneficiaries of my mistake! I'm really glad, though, that you showed the jar-spacing thing as well. I've been spacing my jars a little too closely together.

Thank you so much! I have never heard of this nor, thankfully, have I ever experienced it. I have not left jars in the canner for an excessive amount of time. However, I have put them on a towel on the counter about a half inch apart and immediately covered with a towel. No more. You have taught me so much. I appreciate all you have to share with us…and with others! Blessings

50 years of canning and never heard of this, or experienced it. I’ve always removed my jars immediately after process completed. My mom did teach me to put a towel over the hot jars…I won’t be doing that anymore. Thanks you’re a wealth of knowledge!

I'm glad you told us this. I do the rack, usually, but I have always draped a kitchen towel over them. I will not be doing that anymore. I had read not to have them in a draft, so I would put the towel over them to prevent that. No, I didn't actually have a draft. Lol. Thank you, Pam. You are a jewel. I've been fortunate that I haven't experienced flat sour in anything that I've canned since I did cover the canned jars. This just proves that we need to continue to learn even when we think we know all that there is to know or consider ourselves experts.

The only time that I experienced flat sour was when I left the jars in the canner overnight to cool down. I was new to canning and thought it was ok. No more shortcuts!

Thank you for this information! I've been guilty of leaving my jars in my Nesco (mine behaves perfectly BTW) overnight because I had to get to bed and I'd canned a batch of something after dinner. Well thanks to you I now know better! Thank you for all that you do and have done up to this point to teach us safe canning practices.🤗

Thank you for the carefully worded instructions to avoid flat sour. You make confusing processes so understandable. You explain reasons which will make me remember the instructions just because I now understand why.

Very helpful video. I’m 71 and Pam you have taught me so much .Jim thank you for working along side Pam to bring us the great videos.❤

GREAT education video! I had been leaving my jars in the pressure canner for 3 hrs after it started the "Cool" cycle. The first time I used it when it said it was ready to open, I took the knob off the top, it spurted steam and scared me a little. (The jars inside also rumbled and siphoned almost half their liquid). And since my Mama is in heaven and can't guide me, I get to watch you! And learn science with love for feeding my family safely. Thank you from AZ!

Thanks for this explanation. I knew about flat sour, but not the exact particulars. It’s always good to have the best and most accurate information. I have watched videos of people in other countries “canning” tomatoes by boiling them for a long while, putting in jars, covering with lids and setting them all close together and placing heavy blankets over and around them. I know that’s not an approved method of preserving, but I wonder why they don’t get flat sour? Or maybe they do and they’re ok with the flavor? Idk

I have All American canners and I’m petrified of leaving jars in too long because of a possible suction seal so I’m on the ball with removing as soon as it’s safe to.

Thank you for explaining everything so clearly; even when doing things properly, it's good to know why to do things that way. I continue to learn so much from you. It's a delight!

With years of canning under my belt, collecting recipes, reading about canning, I have to say this is the FIRST time I have ever heard about flat sour. It's always easier for me to follow the protocols, so that may be why I have no experience with what you're describing. However, I have, on occasion, left jars in the canner overnight and/or left them too close together while cooling. Moving forward, I'm using your advice. As always, your channels are always worth the time. Many thanks for all you do!

Never heard of flat sour, and don't think I have experienced it. That being said, my occasional leaving jars to cool down over night in the canner will come to a screeching halt! Thank you for the info!

Something learned and shared from one friend to another. I also have many canning jar rings. When you said you put them loosely on your filled canning jars to store, I too decided I would set my rings loosely on top of my filled jars to store. The other day I saw that one of my filled jars from earlier this year had a little mold growing on top and it had sealed again. In further checking my other filled jars some of the rings had moved down on my jars, perhaps with the movement of the house. I did not feel comfortable with that so I have taken all the rings back off. My new thought is, why do I need hundreds of rings? So I have decided to keep perhaps 50-100 rings and get rid of the rest. Thank you for coming to my kitchen each week. It is like having a trusted friend come visit and help me. Much love Cindy

Thank you for explaining flat sour. I’ve been tempted to leave my products in the canner but then my long term canning history and “book reading” took over and removed my product. Again thank you for sharing.

Thank you, Pam, for educating us about the why as well as the what. I really enjoy all the lessons you share with us. God bless you and Jim.

Thanks for this! I've been canning for several years and have never heard of this! Knowledge is power! Hope you have a great day Mrs. Pam

Thanks for explaining this- I love learning about canning.

Good grief, you have to be the smartest woman I know! I love, love, love learning new information from you. You teach like nobody's business! Thank you for another great teaching moment. K. Billings, A Utahn living the dream in Texas, but wanting to come home

Thank you for this info. I've canned 50 years and never heard of flat sour!

Your videos have so very much useful information, thank you.

I share your videos with my daughter. You cover so many safety tips. Thank you for sharing your experience and wisdom. ❤

Never too old to learn.

You are so helpful! I have learned so much and I have been canning for years. I also see I was taught sloppy canning. Or, I just wanted shortcuts. By using your knowledge I have become a safer, better canner. Thanks so much. You will always have those that deny. Know, that science rules!

Hubby was eavesdropping, which led to a discussion on this. He was curious if we canned outside on a 90 degree day, would we run the risk of developing flat sour as we cooled down the jars outside. We looked it up, looks as if those bacteria like temps above 110 degrees! So we’ll be safe canning outside! Thanks for the good info. Mom taught me to cover my jars after taking them out of the canner. I abandoned that a long time ago!

Always such great information with the science behind it. Thanks, Pam (and Jim!)

My Nesco cool down time seems to depend on whats in it. Sometimes an hour is enough, but most of the time it takes an extra 5 or so minutes. When I open my lid I always open it just partway and put a wooden spoon to prop it open for 1-5 minutes, because I had some siphoning one time when I opened the lid all the way. I had never heard of flat sour, so thank you Pam!

This info is so very helpful. Thank you so much for letting us know about this, Rose. 🌹

I had never heard of flat sour before! Good to know, thank you.

I really enjoy your videos immensely, so informative. I like you have been canning for years, but now I enjoy knowing the science behind it. Thank you! Side note, I have a storage problem too, so I now hang my “extra” canning rings with a string. I just made a large loop with string, place many rings on the string, then pull one end through the loop at the other end. Then I just hang them from the corner of my shelves.

Wow, i dont leave them in the canner BUT was leaving them close together and putting a towel over them. No more. Also ive never heard of flat sour, so thank you for the info.

I learned things in this video that I have never heard of before and never thought of before, thank you!

Im new to canning..i did not know this very important information. Thank you.i learned valuable lesson just now

I learn something new from every video of yours I watch. I am so glad I found your channel. ❤❤❤

We learned this last week that we have canned food that is still good, not spoiled but are dated 3 years along their B B date. So, we are dehydrating everything that we can, or fruit we are turning into jams.

I’m guilty of having left jars in my canner, no more! Thanks Pam for educating us.

Thank you so much. I had never heard of flat sour. So now I understand why some foods can taste unpleasant when canned. just ran and jerked off the towel I had over my canned tomatoes. Thanks for sharing.

Thank you for addressing the towel over the jars. I don't do that but always wondered if it effected the canning

I adore your content. I have two of the electric canners you recommended after testing. I use whichever one is more suitable to what I’m doing. One does seem to be slightly pickier than the other, lol. Thank you!

Again I wish I had you for a teacher however I now have you as a canning teacher! I learn so much from you every time I watch a video. I learned about flat sour & that I need more room between jars as they cool💕

I have heard others mention the possibility of flat sour developing, but no one ever explained exactly how it happened. Thanks for going over the "whys and what fors" in an easy to understand way. You and Jim do an excellent job putting these videos out and it is much appreciated.

Thanks for this video. I am new to pressure canning. Only started in 2021, I have watched many videos where people said they turned the burner off and went to bed. So, I had no idea that could ruin my food and have done it a few times myself. I won't risk it again.

This is one of the most useful pieces of information I have seen in a while. I have never heard of it before. Thanks for the info!

Thanks for the educational reasons behind the rules.

Very helpful information! 👌

Thanks Pam

Thank you so much for the information. This explains why some green beans I had canned last year tasted sour and had to be thrown out. While I had removed them from the canner within the correct amount of time, I did set them on a towel on the counter and had them only about 1 inch or so apart from each other. Now, I can be confident that I know what not to do next time.

This was brilliant and much needed….I’ve done ALL the wrong things ❤❤❤❤

I will be the talk of the table at our weekly luncheon...I am sure no one in my immediate canning group has ever heard of this. Thank you for this info on flat sour..

Thank you for a full explanation. I didn’t know this about flat sour.

Thank you for sharing this! As a new canner, this was news to me! I have definitely been guilty of this. Now that i know better, i'll do better!! I sure appreciate your channel. ❤

You are such a good teacher 🥰

What a great explanation. I watched a video earlier today in which a lady left the cans in her Nesco overnight. I clicked “do not recommend this channel” when it was over. I have been learning so much from you. I am a retired high school teacher and so very much appreciate your methods of presentation. Thank you, Pam & Jim.

Thank you. I never knew this !! 71 yrs and still learning. I have tasted it.

Thanks for breaking the explanation down of how flat sour occurs. I knew not to place my jars close together, but not that it was because the heat expands out.

I am so glad to see a jar of potatoes after they have cooled. My jars were clear and full of liquid when they came out of the canner but then after they cooled they were cloudy and looked like a solid lump. My beans 🫘 were the same and looked like there was not any liquid in them, glad to know they are OK. thanks so much for all you do 😊

Good information! Thanks Pam & Jim!

Uh oh! I know I've left a batch of jars in the canner to cool because it was super late and I went to bed. I can't remember what it was though! I guess I'll find out when I open it.

Excellent Advice! Thanks for the great educational video!

Learned so much , yes I have been doing the cover with a towel.

Thanks for the lesson, i have not heard of this.

Thank you for letting us know.

I just got a hiney smack from Prof. Pam 😆 I guess when I said, I was told by Carey to leave my jars in the canner for 1 hour, I always set a timer when it finished, to make sure I waited "the 1 hour". I only did that because I was afraid of messing something up, and didn't want to take any chances. I know these teaching videos are for our own safety, and it's appreciated. But, the more I learn, the more I'm thinking I don't want to be a canner. I'm just thinking for my own sanity, and not having the worry of- did I mess something up, I might just stick with the many other ways to preserve my harvest. Thanks Ms. Pam.

Thank you. I researched and use a Nesco after researching. My Nesco takes an hour. Oh my gosh, I put my jars together because that is how I learned to do it from my mother-in law. AND I PLACE A TOWEL OVER THEM. Funny how we learn some of the old ways work and others are wrong. Thanks for teaching us this. I will now change my ways.

Good to know. I've never had that happen.

Wow! I just learned something new. Thanks.

Thank you Pam. Stay warm and have a great week.

I have been waiting for this video ever since I heard you say "flat sour" on another video or in the comments. I can't remember which. Thank you so much. You are an educational gem! 💎 👍🏻😊

Thank you for this information. Knowledge is power. I have not left my jars in the canner and now I won't even think of it!

I've been canning for over a decade, maybe two, and never heard of that. Very interesting!

Love, love, Love you both! I have never heard this and almost didnt watch this today. Im so glad i did listen, ive been taught to cover my jars with a tea towel, i wont do it anymore. THANK YOU SO MUCH for your common sense, your perspective from science and experiences. 😊

I've never experience Flat Sour before - I learned something new today. Thank you!

Thank you for this information I did not know this !!

Wow,thank you for all the information, I have learned alot with this video.

I had not heard about flat sour. Appreciate this info to discourage short cuts!

Pam, thank you for your detailed explanation on flat sour. I live at a high elevation of 5460 feet and my daughter who also cans, lives at a 6200 foot elevation. Accordingly, we follow the instructions and increase our processing time as advised. We have had a problem with siphoning following canning when we follow the stated instructions in the Ball canning book for the recommended time of removing the jars from the canner. We were advised to leave the stove top canner (or water bath) for 45 minutes to one hour as soon as the processing time is complete to avoid the problem of siphoning. i had not previously heard about the flat sour problem and i am concerned about canning safety. I have watched many of your YT videos and recall that you also live at a high elevation. How do you handle the problem of siphoning in a high altitude canning kitchen and avoid flat sour? Pam & Jim, thank you for your time and consideration in teaching so proficiently.

I was scared to death the first time my broth jars syphoned like that! Even so, I love my troublemaker canner

Thank you for letting us know about this. I had never heard of that and have been canning for years but only water bath. I do plan to do some pressure canning I bought the Nesco smart canner and tried it once doing chicken and it was like it never went into pressure. The steam shot up almost to my ceiling in my kitchen under pressure and not under pressure and we could actually smell chicken as it was processing. So we didn't eat it. Someone suggested that I check the seal and the vent and of course I haven't got around to doing that yet as I was going to do more in summer. I really liked the idea of this canner since I had never done any pressure canning. Thank you always for updates on everything and why we need to pay attention to everything that we do.

Thank you for this information I really appreciate it.

“Nasty-ish” 😂😂😂 Thanks, a needed a lighthearted moment.

Never heard of flat sour. Thank you so much for this information.

Thank you ,I had no idea!

Thank you! Never had heard of this and learned a LOT!

My Nesco is in time out. Started not venting properly, I’m back to my Presto canner.

The lost ways is advertising on your video promoting water glassing eggs as a way to preserve eggs like the old days.... bahahaha wrong channel to do that because now we (RoseRed Homesteaders) know this way of "cowboy canning" is dangerous! Thank you for the valuable education you provide!

I have had a couple of jars break on me when I removed them too soon. I let them sit in the canner for at least an hour with the lid cracked a little. Canning is very temperamental. I will have to check my potatoes 🥔 . I left them in the canner overnight as well because I was exhausted. Thanks for all your tips. I have never heard of flat sour before. God bless you.

Thanks for this information. I've heard of flat sour but I didn't know what caused it.

Thank you so much for the information. I love the way you explain things. I started canning in 2021 with a Presto that my son had. I have bought my own since then and now im ordering the Nesco electric canner. You are a great teacher and i love learning from you.

Wow. THANK YOU for teaching me that. I have been guilty of all of the poor habits you mentioned on occasion. THANK YOU, THANK YOU, THANK YOU!

Good information. I’ve been canning for a lot of years. I’ve never heard of flat sour. I don’t usually leave things in pressure cooker but there may have been a hand full of times. Well never again.

Thank you. Great video!!

Thank you for sharing this, Pam. I am new to canning and you have covered various important issues for safety and good food quality.

Had never heard of this

I have never heard of flat sour. I have not experienced it I guess because I always take my jars out of the canner as soon as the pressure is zero. Thanks for the info!

NEVER EXPERIENCED THIS OR HEARD OF IT, THANKS FOR THE INFO

Thanks, Pam and Jim! I always learn so much from your channel!!