Hello, and a pressure canning question...

[CanningPeaches]

Hello, everyone. I'm new here, so I'd like to take a moment to introduce myself. I'm 34, married, enjoy cooking and baking and dancing, and have been canning for about five years (pressure canning for about half a year).

My question/issue is this: how do I increase the success rate when I pressure can? I've followed the instructions on the canner insert, read plenty of stuff online, done my research at the USDA site...and still I'm having problems with seal failure. I don't overfill the jars, I make sure the top is wiped clean, I finger tighten only, am mindful of the pressure...and still I have problems. I usually only get one jar to seal, maybe two if I'm lucky.

Someone I knew from another forum gave me the advice of taking the weight/rocker off when the required time was up to depressurise it more quickly than it would otherwise. I tested it with a batch of water (in jars), and it helped, but I still tend to end up with two or three that don't seal.

Any advice? What could I be doing wrong?

 

[sparrowgrass]

No, no, no--don't take the weight off, that is pretty much guaranteed to siphon liquid out of your jars.

Let your canner cool by itself--don't move it, don't touch the weight. It will probably take about an hour.

Are you bringing your flats to a simmer in a pan of water first? Don't boil them.

What brand of lids are you using? Some off brands don't work well.

Maybe you are not tightening enough? Ball now has a torque wrench for jar lids that tightens them just the right amount, but I just tighten them with my fingers, and then one quarter turn more. You don't want them cranked all the way down to where you can't get them off, but they do need to be screwed down.

 

[CanningPeaches]

Thank you for your reply. OK, so the admonition to leave the weight on is to prevent siphoning. Good info. But why, then, would they still not seal when I left the weight on like that? I get BETTER sealing with taking the weight off, although I didn't think to color the canned water to detect siphoning.

Yes, I keep my lids (Ball) in a pan of simmering water. I keep the water in the canner at a brisk simmer while I'm filling jars/loading the canner. I keep the jars waiting in the hottest water I can get out of my tap.

So, if you're saying that you tighten the bands 1/4 turn beyond finger-tight, then pressure canning lids should be significantly tighter than water canning lids? Interesting.

 

[mcnerd]

There is no difference in tightening the lids between pressure canning and a boiling water canner, which should be finger-tight only. Any tighter and the ability to purge the air out of the jars during processing can be compromised.

I don't have a definitive answer on why your jars aren't sealing properly since I can't see you in action, but you are obviously doing 'something' not quite right. You just have to examine each step you take until you figure it out. Don't get too discouraged.

One of the evils of lid sealing is a rapid temperature change. Make sure there are no fans or drafts in the area of the canner. After the heat is removed and pressure has dropped to zero, you should wait 15 minutes longer before removing the lid. For a Boiling Water Canner wait 10 minutes after removing from the heat. This delay allows the super-heated jars to cool slightly so there is less of a temperature shock.

Also make sure the jars are NOT tilted when lifting out of the canner and placing on the counter to cool. There is a tendency to tilt to remove water from the top of the jar. Don't.

Other than the tightness of the lid, the next usual issue is not enough heat in the processing, but this is usually related to a Boiling water Canner and achieving a true rolling boil. This is not an issue with a pressure canner, but the full boiling level (240°F) can be missed if the canner is not vented of air for 10 minutes before the weight is added and pressure allowed to build up.

Keep in mind you can practice with just jars of water filled to the appropriate level and run for at least 10 minutes. You may waste a few flat lids but that's cheaper than doing it with food, just to figure out why the jars aren't sealing.

 

[Diana Walstad]

I always reuse lids. Either they seal or they don't. However, I carefully remove the lids so as not to dent the edges. Only when the gum layer gets really thin do I stop reusing lids. I have reused Ball's lids at least five times without any sealing problems.

Also, I don't sterilize lids separately. (I wonder if your lid's gum layer got wet from this procedure and prevented the sealing?) When you bring the canner to temperatures above 212F, you are sterilizing the lids along with the jars. The lid's metal will conduct heat readily to underside of the lid, thereby killing any bacteria on the underside. Plus in canning peaches, you are working with an acidic food, in which all bacteria are pretty much wiped out at 160F to 180F, so there's little chance of contaminated fruit. I have never had a contamination problem.

As for your sealing problems, I had trouble until I started tightening the rings a little more. The main problem is when food boils out of the jar. When food juice gets between the gum layer and the jar rim, that's when lids won't seal.

Hope this helps!

 

[mcnerd]

Wow, you really like to live dangerously. I do not EVER recommend anyone reusing flat lids. People did that once back in the 70's when there was a shortage of them and it resulted in one of the highest levels of food poisoning in history. You've been lucky, but if you end up with botulism poisoning all it takes is one instance.

 

[Diana Walstad]

Thanks for the information. I would love to see the documentation on the 1970's outbreak.

That said, there's no botulism risk from canning acidic foods like peaches. Peaches have an acidic pH (below pH 4.6) that does not allow the spores of Clostridium botulinum to generate. Therefore, botulism is a moot point when canning peaches and many other (but not all) fruits.

Any instances of botulism would have to be from canning low-acid foods, that is, those with a pH of 4.6 or greater. This means meats and vegetables.

When I can meats and vegetables, I use a much greater heat input than I do for canning fruits. Whether the lid is old or new shouldn't matter. A certain amount of heat will kill the targeted bacterium whether it is on an old lid or a new one.

 

[mcnerd]

I believe it was about 1974 or 1975 and you could do an Internet search and find it, but it was in the early 90's that research and technology made breakthroughs on the issues of bacteria, especially the C. Botulinum spore and resulted in all canning recipes and publications to be reprinted.

Unfortunately your rather simplistic approach to bacteria and canning will not protect you from potential food poisoning. In fact, your individual immune system may have protected you on more than one occasion without you realizing it. Sure you can continue with what you are doing/thinking, but I would seriously recommend you update yourself with modern answers and procedures, especially if someone else partakes of your canned foods.

A good first step is to take the online *free* course on Food Preservation to find out how current your information is. It's offered by the National Center For Home Food Preservation through the University of Georgia. They are the authority for home canned and preserved foods. The course can be completed in 1-2 days if you are up to date and will be given a Certificate of Completion if successful.

I'm not sure what you mean by a "greater heat input" for low-acid foods, but the requirement is 240°F which can only be achieved with a pressure canner for a specifically tested period of time for each food type. In some circumstances the C. Botulinum spore can survive pressure canning so it is not a gimmee event. It is also possible for other serious bacterium, yeasts, molds, or fungi to survive a boiling water bath if done improperly. Even C. Botulinum can become a serious issue if the acidity is not sufficient or does not penetrate into the food itself.

 

[taxlady]

Wow, you really like to live dangerously. I do not EVER recommend anyone reusing flat lids. ... You've been lucky, but if you end up with botulism poisoning all it takes is one instance.

+1 Re-using lids is a really scary idea.

 

[GA Home Cook]

I have been using pressure canning for years. I have done meat (beef stew), veggies, and many other things. The number one thing is to keep the contact between the lid and jar clean. I fill the jar, wipe the edge of the jar with a damp paper towel and put the new lid on. I do reuse the rings, as I remove the ring after sealing and just store the jar with the sealed lid. That way I don't have to buy rings and lids, only lids. I have gotten several uses out of rings before the begin to rust. One area you may want to look at is how full you are filling your jars. Once the inside of the pressure canner heats, it is well above the normal water boiling point. Ala - kills the bacteria. If you fill the jars too full, you can get junk between your lid and jar when the contents begin to boil. I leave at least 1 inch of space in my jar for anything except jelly - which I do in a water bath anyway.

 

[taxlady]

I have been using pressure canning for years. I have done meat (beef stew), veggies, and many other things. The number one thing is to keep the contact between the lid and jar clean. I fill the jar, wipe the edge of the jar with a damp paper towel and put the new lid on. I do reuse the rings, as I remove the ring after sealing and just store the jar with the sealed lid. That way I don't have to buy rings and lids, only lids. I have gotten several uses out of rings before the begin to rust. One area you may want to look at is how full you are filling your jars. Once the inside of the pressure canner heats, it is well above the normal water boiling point. Ala - kills the bacteria. If you fill the jars too full, you can get junk between your lid and jar when the contents begin to boil. I leave at least 1 inch of space in my jar for anything except jelly - which I do in a water bath anyway.

Sounds reasonable to me. I pressure canned for a few years and never had anything not seal. In fact, I pressure canned jams and preserves, just because then I never had any seal failures. I also wiped the top of the jar with a paper towel (when I necessary) and made sure to leave at least an inch of head room.