I put this here because I am looking for a GQ style answer but feel free to move if it belongs over there.
I have an attachment for my vacuum sealer like This one and it creates a very tight seal, much tighter than you will get via the water bath method used in food preservation. (essentially boiling the jars with the food in them and then letting them cool, the vacuum is formed during cooling when the lid forms a seal and the cooling causes everything to shrink back down their normal sizes from their expanded sizes)
The reason I dropped this in GQ is related to the physics involved and the food safety aspects. You are not supposed to re-use the lids because they may not seal correctly the second time around in a water bath (or pressure cooker for that matter) What if you did your usual prep, cleaned and boiled everything then instead of a water bath you vacuum seal the jars full of your pickles or whatever and THEN give them a water bath per the usual directions.
Would this method allow you to bypass the single use per lid due to fears of a bad seal forming since you already have a seal formed in advance?
Note this question has nothing to do with saving money, the lids are pretty damn cheap, but when it comes to the stage of running a handle or something around the jar to get the bubbles out I have found a vacuum seal does an incredible job at this task and have used it a few times with good results. I am just looking to the dope for insights.
It would shock me if the vacuum sealer could achieve anything like the vacuum created by water bath canning. The vacuum in water bath canning doesn’t just come from thermal expansion, it primarily comes from the phase change of water to steam, displacing the air. After cooling and condensing the volume of steam is less than 1/1600 of its original volume. That’s where the reduced pressure comes from.
If you use the water bath method after using the vacuum sealer method you’re going to break the original seal and establish a water bath seal.
Plus I think the real issue with the seal is the adhesive on the jar lids. Once you’ve melted it in the water bath and pried it back off, it’s never quite the same again, and they can fail even under ideal use - which is why they tell you to pick up the jar via the lid to test them (after the cooling period) and to never store canned jars with the rings on top, so you can do this right before use, avoid rust from rings damaging the lids, and generally check for issues. I wouldn’t want to risk botulism and/or ruined food over the cost of a lid.
If you hate wasting them, get some Tattler brand reusable lids (plastic tops, rubber gaskets) and stock up on a bunch of spare gaskets.
Breaking the seal on a vacuum sealed jar is really difficult with your hands alone, It pretty much requires something to pry the lid off. I dont have any way of testing the difference that I can think of at home though.
Here is a link to a table some guy selling a vacuum sealing device claims represents the inches mercury vacuum pulled by a variety of food storage devices. The food saver, which is the one I have, pulls 24.2 inches mercury of vacuum. That means the pressure insde will be 5.72 inches of mercury, 29.92 atmospheric minus the 24.2 inches of vacuum.
The pressure in a water bath sealed jar will be whatever the vapor pressure of water is at the temperature the jar is. at 25 degrees C the vapor pressure of water is only 23.8 mm of mercury, less than one inch. Water bath canning gives you much higher vacuum than the food saver, and even more than the PumpNseal being touted as the best thing since sliced bread.
Also, the vacuum sealed jar will still have 20% oxygen in it, while the water bath sealed jar will displace the oxygen with steam.
This is a good start, remember you dont need the whole lid, just the inner top, the ring you can use over and over
Interesting info, I have to wonder if I am doing something wrong. I know for sure some of my home canned jars have a fairly light vacuum to them compared to the sealer but perhaps it was just a couple of them.
The point of canning is to basically seal the jar tight so that air cannot get in, and then essentially heat-sterilize the interior of the jar so that there are no spoilage organisms inside.
The vacuum is only useful as far as it actively keeps the lid on the jar. If you reuse the lids, the adhesive isn’t as effective the second time around, so you run a much larger risk of having air (and spoilage organisms) getting into your canned food.
You don’t need a huge vacuum for canned food, and I’m not even sure if it’s strictly necessary or just a consequence of the canning process.
The lids of mason jars often bend when you’re removing them, making them useless.
However the jars and bands can be reused multiple times. Jars need to be thrown out if they crack, and bands are just used to hold the lids on. You can just buy packages of lids each year (at around $2 a dozen) and reuse the rest.