Pressure canning: losing fluid from jars

I'm fairly new to pressure canning and am having some siphoning problems when canning chunkier vegetables.

Recently I canned my first tomatoes and while the crushed tomatoes canned fine the whole tomatoes all lost about a 1/4 of the water in the jar.

Yesterday I canned the last of my swiss chard harvest and again lost quite a bit of liquid in the jars with one particular jar being nearly empty of water.

From what I read there can be many reasons for this loss so I make sure I hear slowly and cool for extended periods before opening.  I also understand that air in the product your canning and actual absorption of the liquid into the food being canned can also lead to liquid loss but there is definitely chard water in the canner when I'm done.

I'm confident the product is fine.  They are pint jars, processed for 70 min with a 10 psi weighted pressure release and all the seals are solid.

Anything else I can do to prevent such loss in future?  Maybe chop the leaves more so it's less chunky ect

Thanks!

Maybe your jars were too full? The first time I canned, I didn't leave enough headspace and also had a jar leak into the canner.

Martin, welcome to Permies!

You raise a very good question. I've been canning for many, many years and still have this problem. One thing that seems to help, is to make sure the headspace is exactly what's recommended in the directions for each particular food. That's the advice that was given to me, and while I've found that this helps, I can also say that it doesn't completely solve the problem. Hopefully, others will have tips that will help even more. Permies is an excellent place to ask questions like this.

I have read this is due to maintaining and uneven pressure,  I have no idea if this is true. It seems to me if this were the case, then all the jars in a batch would have excessive space at the top.  I will say that when I am ultra cautious to maintain an even pressure this does not happen. But I have not tested this enough times to be confident in any direction.

John F Dean wrote:I will say that when I am ultra cautious to maintain an even pressure this does not happen. But I have not tested this enough times to be confident in any direction.

John, could you explain how you do this? I pretty much leave the whole thing alone once it reaches the proper pressure, except to gradually turn down the heat if the pressure continues to build.

Of course, that is the problem. I sit on my rear next to the stove (ip) and watch it.  Not very practical for real life.  With a wood cook stove, this would be even more difficult.  As I commented, I have not tested this theory enough times to be sure ... and I have no plans to.

I highly recommend a weighted gauge on the pressure canner. They allow for consistent pressure during the whole process.

I generally consider fluid loss from the jars to be due to too rapid cooling. This can happen if the pressure relief valve or gasket leaks causing rapid depressurization once heat is removed. It can also be caused by opening the canner before it's sufficiently cooled.

A steam-leak in the canner, or starting with insufficient water may also lead to depletion of the water in the canner and cause the jars to boil over. If the jars are sitting directly on the bottom of the canner, heat can be transferred directly into them, causing over-heating and boil-over. This can be avoided by sitting the jars on a rack of some kind that separates them from direct contact with the bottom of the canner.  

I have experimented with using a gauge and a weight.  It looks like there is a T under your gauge. What is attached to the T?

John F Dean wrote:I have experimented with using a gauge and a weight.  It looks like there is a T under your gauge. What is attached to the T?

The T contained an additional pressure relief valve.

Joseph Lofthouse wrote:

This can be avoided by sitting the jars on a rack of some kind that separates them from direct contact with the bottom of the canner.

I bought a pot for boiling water bathing jars that wasn't a specific "canning kettle" and it didn't have a rack in it. I bought a perforated pizza pan that was exactly the right size and when it's put in the pot upside down, it holds the jars up by about the same amount as the racks that came with my large pressure canner. They were available in 1" increments of diameters but some sizes had to be ordered in, which was fine as I was planning ahead and able to wait. Just an aside in case people are having trouble finding a rack to fit.

So glad to see this question! Greens seem to be especially susceptible to this problem. While I've never had quite as significant a loss as you describe, my jars typically come out showing loss.  I steam my greens lightly before filling the jars, and have wondered if that's producing too dense a pack.  On the other hand, more pliability makes it easier to be sure there are no air pockets, and the steaming technique I use allows me to capture the water for use in topping up to required headspace.  

Still, some jars lose more than others.  My alternative theory is that it may have to do with the ripeness of the greens themselves, and how long it's been since they were picked before I get them processed.  

Even when the water level in the jars ends up lower than the content, I've never found the product to be less than wholesome.  But I've gone to using only quart jars for canning greens precisely because of this phenomena.  It's true that quarts take up more shelf space, but a 3/4 full quart jar is still a more usable quantity of greens than a 2/3 full pint.

Bravo YOU for canning this year's harvest!  Be sure you mark your jars with the month and year - so you can remember how our lives all changed in 2020.

Thanks everyone for there input.  Seems like this question exists for everyone.  I will take a look at all my seals and ensure a tight and leak free fit.  I use a presto canner with after market weights and each canning session I feel like I learn a little bit more.  I'll keep at it and if I discover anything more I'll be sure to add it here.

I've had the same issue with water leaking out as well. I figure that I either had the flame set to high. or the rings weren't snug/tight enough.. another issue could be the threads on the jar's and/or the ring's. if there's a tiny chip in the thread of the jar. will be a major problem. I've thrown away ring's simply because they wouldn't go on snug or tight.

Martin, thanks for reminding us all with your wise words:  "... each canning session I feel like I learn a bit more."  

That's so true!  This is just my 6th season, and I know I have a ton more to learn.  Too much fun!

So far, as a newbie, here is my experience.  FOLLOW ALL DIRECTIONS TO THE INCH/SECOND/AMOUNT, ETC.  Also, today in a rush to do potatoes and carrots, I dropped the pressure on the potatoes so I could get started on the carrots, and now I have 5 quarts of potatoes with no water in them.  I did the carrots per the instructions and didn’t cut any corners, and they came out perfect.  Mashed potatoes for breakfast, lunch and dinner for the next 2 weeks.  I learned.

This is a common problem. It is caused by the pressure in the cooker reducing too fast. When there is no pressure in the cooker and the jars are still above the boiling temperature they simply boil over. To keep this from happening reduce the heat to the canner slowly by ramping down the stove temperature over a longer period of time rather than suddenly turning off. Allowing more time for the pressure and heat to reduce over a longer time and for the jars to cool within the cooker over a longer period of time is probably the only way you’ll ever stop this problem. It also helps to put a few dish towels on top of the pressure cooker at the end of the process to keep the cooker from cooling off too quickly. Any leak in the pressure cooker allowing steam to escape faster will cause this problem also. Never decrease the pressure quickly and always allow as much time as possible for the cooker to cool off. Check your gaskets and make sure pressure is being held in the canner as it cools off. The pressure in the cooker will naturally decrease as it cools off without venting. Good luck.

We bought a Presto electric canner.
It is digital.
It runs itself.
You do not have to watch the temperature.
Using this device frees up our stove for other uses.
David

Other then the pressure Presto canner, if your lids are too loose the liquid can siphon out. The lids need to be just slightly tighter than when using Tattler lids.
Too tight is also not correct. Gasses need to get out. I usually screw the ring on snug, then back it off and then slightly retighten the ring. Just enough to feel resistance.
David