Home canning has made a comeback and if you do a lot of it, chances are you’ll run into the situation at least once, where you question the edibility of something you’ve just pulled out of the pantry. Whether it’s because it didn’t seal correctly to begin with, or that it came unsealed while in storage, if you know what to look (and smell) for it makes decision making easier. I tend to err on the side of caution if I find myself questioning a jar of something that I’ve canned, but most of the time the signs your canned food has gone bad are pretty obvious. The one exception to that is if a home canned product has developed botulism. You can’t taste or see botulism but you’ll become quite sure about it real quick if you consume a jar of food that has botulism spores growing in it. Botulism sickness, also known as food poisoning, begins with weakness in the face that then spreads downward to the rest of the body. Other symptoms, according to WebMD, are blurred vision, difficulty speaking and swallowing, shortness of breath and nausea and/or diarrhea. Because it is technically a neurotoxin traveling through your body, if left unchecked, botulism poisoning may be fatal. Using correct canning methods for the food and keeping all supplies and work areas sterile is the key to botulism free home canning. Any of the home canning books will walk you through the process and give you the correct methods, but my favorite is the Ball Blue Book – Guide To Preserving
For spoilage that you can see and taste, look for the following clues:
- Bubbling in the jar.
- Bulging lids.
- A lid that spews when you open it, indicating the contents have been developing pressure or gas inside the jar.
- A lid that has lost its seal.
- A jar that has had visible seepage (on the outside of the jar coming from the lid).
- Food that has an odd color.
- Food that has an odd smell.
- Any kind of film or slime covering the top of the food.
- A lid that moves when you press on the top. Canning lids have small indented “buttons” that will be completely concave when they are properly sealed. A “button” that moves is not sealed.
A few handy tricks to have up your sleeve:
- Don’t store your jars with the rings on. If pressure develops inside the jar, an unseal will be forced by the pressure. A lost seal makes your decision easier as it is a clear sign of spoilage. To bring that point home even more, a jar with a ring still on it may actually lose its seal and then re-seal. When this happens it’s called a false seal. Albeit lightly resealed, it may make it less clear that there has been a problem taking place.
- Before you put your jars in storage, take the rings off and give the lids a trial lift with your fingernail. If the seal is not good, you’ll be able to lift it off. If the seal is good, you won’t.
- If you’ve taken the advise above and are storing your jars without the rings, put foods that are more prone to building pressure (tomatoes, etc.) under a shelf that will at least help contain the mess if one pops the seal and lid.
- If you’ve just finished processing and discover a jar that has not sealed properly, just stick that jar in the fridge and use it within a few days. Generally the rule of thumb is no more than 24 hours after processing, but use your judgement if it already looks “off” or if it has been subjected to excessive heat while sitting out waiting to seal.
- Store your jars in a dark, cool place that is not subject to large temperature swings. (another thing that can cause an unseal and reseal.)
Canning is an important part of being self-sufficient and is extremely rewarding. Follow sanitary methods and the guidelines in a well-respected canning publication and know what to look for. Then follow golden rule #2; If in doubt, throw it out! Happy canning:)
Read this and others like it on this week’s Homestead Blog Hop at SimpleLifeMom.com
As long as they are scrubbed and sterilized thoroughly and have no left over stuck on crud, you can reuse the jars themselves and toss the flats and rings. With the lid shortage going on right now that is pretty painful, but you are correct in NOT reusing the rings.
Is it safe to re-use canning jars that have had spoiled food in them? I know to replace the rings/lids, but would like to be sure about the jar itself. Thanks. Kim
Hi Richard, thanks for reading!
I am a supporter of the practice of taking the rings off stored home-canned goods so that you know if there was an event that caused the jar to unseal and then a false seal to be created by the ring. That said, an audible pressure release is a good sign that the original seal was still intact. As far as how do you know if the audible sound was air replacing the vacuum or gasses being released, if there were gasses formed inside the jar, you would likely have an “off” smell to the contents and any formation of gasses would also eventually lead to a bulging or warped lid if the ring was still on. If the ring was off, the seal would break and the lid would pop off. It’s a mess in the pantry, but preferable to wondering.
So, my other thought… There is such a thing as “Flat Sour” which is not poisonous, but does make the canned goods unpalatable. Flat sour has an off taste and is caused by leaving canned goods in the canner to cool instead of taking them out, or from putting them in a space that traps heat so they don’t go ahead and cool. The gist of it is that the heat loving bacteria overgrow when the canned goods are left in an environment where they cool too slowly. They call it Flat because there is no gas formed from this overgrowth. There is a great article about this on Healthycanning.com that you could look over to see if that matches what you experienced.
The Lid was tight. The lid button still depressed. Smell was not unusual. Audible pressure release.
Questions are, how do I know if the audible sound is air replacing the vacuum or gases being released. And after eating, there was a slight metallic aftertaste. This has been in a jar of Chicken and a Jar of Pinto beans. If it wasn’t for the metallic aftertaste, I would have not had any concerns.
I always err on the side of caution with canned foods, whether I did them or someone else did them. If it were me, I would open the jar and listen carefully to see if it has a sound like pressure releasing, or the jar lid going “pop”. If the top has the little button indentation in the middle and that is not sucked in prior to opening and there is not pressure release when it’s opened, I would toss it without hesitation. Good luck, I know that’s got to be frustrating with a brand new jar of goodies! 🙂
I actually ordered some jarred calibrean chili peppers a 4 months ago and just took one of the jars out to use it and the top popped up after I pushed on it. Was it not processed correctly and how do I know if they are safe to use in a recipe?
Hi Elaine! It’s hard to say without knowing how and where they’ve been stored. Personally I’m not as comfortable pushing the limits with tomatoes and things that are water bath products and haven’t gone through the pressure canner. I’m in a few different canning groups and some are adamant that things like that are still good. I can’t say I would agree, but to each their own! 🙂
I’ve got some canned tomatoes
Almost 6 years old, they look as good as the day I canned them,
And the lid is on tight. Do you think I should use them, being this old?
Thanks,. N Elaine
Hi Russell, generally speaking, if you keep the jars in the fridge they should be fine but it sounds like the last batch of three haven’t been refrigerated. Things stored in vinegar are a bit more forgiving because of the ph of the vinegar, but to be able to leave them out and be certain they are safe, you would need to “process” them which would be to place the filled jars, with lids secured, into a water bath canner and boil for the specified time for the type of item you have in the jar. That process would give you the sealed/pressurized jars you reference. In your case, with peppers in a vinegar solution, you probably could follow the processing times for one of the pickled pepper recipes in a canning book such as the “Ball Blue Book”. Just check your ingredients to those in the recipe you’re using the processing time for. There are things that have been canned or preserved in the past in ways that don’t match what is recommended today, but personally, I feel like safe is better than sorry, especially when recommending to others. 🙂
I grew a bunch of different kinds of hot peppers, mostly jalapeno. I got some canning jars and boiled them and the lids for 20 minutes, then when they cooled a bit I put in the cut up peppers with some fresh garlic and thime. I filled the jars half way with apple cider vinegar, half water and a tablespoon of pure sea salt. I stuck the two jars in the fridge and ate one before it could have gone bad, but I still have the other one. I’m using it and havent had any problem. I used the same recipe on the next set of three jars. These I left on the counter and added some dill to one of them. The lid hasn’t been tight on that one for a couple days, but the temp hasn’t changed so it might still be okay. I think once you open them, you loose the seal and pressure inside. I don’t really know and I bet I’ve done it all wrong, but does it look to you like I might kill myself with these peppers?
Thanks, Liz!
These are some great tips, this is always my greatest fear with canning. Thanks for sharing on Homestead Blog Hop!
Great tips. I’m new to canning and need all the information I can get. So far I’ve only done water bath items. Maybe this year I’ll try my pressure canner for the first time. – Margy