What if you leave your jars underfilled when canning? How close do you have to be to the correct headspace? Sometimes you come up a bit short of filling jars...
More than the recommended is quite okay. The recommended headspace is the minimum amount for proper sealing. It is the headspace that the vacuum is created in. Too little headspace, not enough vacuum and the jar may not seal well, plus the contents may come out when processing. A lot of headspace equals a lot of vacuum and a good seal.
Leaving a 2 or 3 inch head-space does not mean you have a better seal. If in the process you lose a little the product will be OK if it seals. Always leave the recommended head-space when packing jars. What happens during the processing is another thing. Pro responses welcome.
It is important to get it reasonably close to the recommended headspace called for in the recipe. You really do want a good seal for safe storage.
See NCHFP FAQ answer at the link below.
Here is a link that might be useful: Do I really need to leave a certain amount of headspace in the jar?
Agree. Too much does not mean a better vacuum. And long-term storage of low level jars is not safe. The air space allows for discoloration, molds and mildew, and seal loss to happen.
You can safely have a little more space than the recommended such as an inch vs. 1/2 inch as sometimes happens with siphoning but much more than that should be avoided and those jars should be used first or even refrigerated depending on the product. EX: you can't safely process a jar that is only 3/4 full.
If you are low on product then either use a smaller jar, fill the jar with additional liquid to the correct level, store the leftover in the fridge to use fresh, or pitch it.
The link Bill provided explains in detail.
Well, personally, I've never had problems with too much headspace, and the jars with a lot of headspace are usually harder to open, so I presumed it due to increased vacuum.
"If too much headspace is allowed, the food at the top is likely to discolor. Also, the jar may not seal properly because there will not be enough processing time to drive all the air out of the jar."
I can mostly using BWB. Very easy to see if there is still bubbles coming out of the jar at the end of the recommended time period. If so, they stay in the BWB until no more bubbles escape. That is how I was taught. Just seems common sense to me. You're trying to get the air out. If there's still air coming out, then it's not done yet. Plain and simple. And I ALWAYS test the seals afterward by trying to open the jar with my fingers. If the jar stays sealed, then the vacuum is good.
More headspace wouldn't necessarily mean a stronger vacuum. If you can't get all the air out, the vacuum won't be as strong as if you do.
How can you see whether bubbles are coming out of the jars while the water is coming off a boil? There are still little water vapor bubbles forming on the surface of the jars that could be confused with air.
If the last jar is almost enough (an extra half inch of headspace or less) then I go for it, and I usually fill the last two jars together before capping to let me even them out if necessary. If I have half a jar left, that's my prize for canning and I get to eat it right away.
You never get 'all the air' out of a canning jar anyway. The hot gases and steam are in an expanded state, push out of the jar as it's processing, and when they start to cool and contract, pull the jar lid tight against it. So, just EXACTLY how much air is in the headspace doesn't have anything to do with getting all the air out, just enough to form a negative air pressure and therefore a vacuum. If the contents aren't quite up to the level of the full jar, it really doesn't affect the surface area of the liquid much, and that is where the molds would start, on the top of the liquids in the jar, because the spores are airborn.
No, I'm not a canning expert, but having enough headspace seems more of a safety and quality issue than not enough.
Oh, this is good to know! I was just wondering how exact I had to be with headspace.
So, just EXACTLY how much air is in the headspace doesn't have anything to do with getting all the air out, just enough to form a negative air pressure and therefore a vacuum.
Sorry but if that was the case then there would be no reason to abide by the different head space recommendations for different density foods. We could just fill each jar with however much or little as we wished.
We could also ignore all the tested and recommended processing times. And we wouldn't even have to worry about using the plastic probe to remove any trapped air in the jars before sealing. Just let the processing take care of it.
I don't think so!
Eliminating all of the air from the jar and insuring that the proper amount of head space remains is one of the primary purposes of processing and one of the most important aspects of safe home canning. Those rules are ignored at your own risk. Sure some minor differences do happen. Those jars are supposed to be refrigerated or used first and are not considered safe for long term storage.
Please don't make the mistake of assuming that the only purpose of headspace and processing is just sucking down the lids.
Be safe and do it right.
Monday, as my friend arrived to sun by the pool she said: "what the heck are you doing?"
Why repacking/processing my pickled red cabbage, see the air bubbles trapped in the bottom, I replied.
Darn it, packed too tight and the juice didn't filter thru.
Old habits die hard Dave, lol. I still use a metal bread knife for the sides in a pinch.
I realize this string of posts is several years old but it is quite helpful. I canned a variety of whole peppers yesterday following instructions to put two slits in each pepper and leaving the recommended head space. I was careful to be sure to get the extra air out of the jars and peppers using a skewer to dislodge the air. I lost a lot of additional air this way and added more brine to the jars. I processed in BWB for 15 minutes and had 7 perfectly sealed jars. However, I ended up with floating peppers (which have settled a bit more today) and an inch of headspace at top of jars. This gives me an uneasy feeling! I am no stranger to canning and I have never experienced this before in all the years of canning pickled asparagus. Low jars will go in the fridge and be eaten first. Good jars, well I will watch them closely. I definitely go by the rule, "When in doubt, throw it out!"
Has anyone ever canned whole banana peppers before and experienced these same results? I could use some tips and tricks on successfully canning whole peppers. We have a garden full of them and would prefer them whole.
In all likelihood they will sink further over time as the peppers absorb more of the brine and the weights equalize.
As far as the headspace is concerned, this is a risk with whole peppers. All you can do is continue to what you're doing now - make every effort to remove what air you can and top up the brine afterwards.
You might also consider packing fewer peppers in the jars, increasing the ratio of pickling solution to product. This will reduce excessive absorption. Over-packing is the source of many canning problems.
Personally, I wouldn't be overly concerned if I ended up with an inch of headspace in some of the jars. The brine for pickled peppers is highly acid and it's unlikely the product would present problems. Using those jars first is reasonable but I wouldn't obsess over the risk.
Make notes, observe results with varying batches, and over time you will arrive at the ideal proportions and fill ratio.
gsherer - you really need to start a new thread with this question for best results. Meanwhile the search here will pull up many discussions on canning peppers and how to avoid the problems you encountered.