I live in Italy - the Quattro Stagioni brand here has been around for more than 30 years, and it is considered the golden standard for in-house canning (other Bormioli glass products are well regarded, too); everyone I know who canned something in his or her life have been using them, and I've never heard of anybody saying anything but great stuff about them. It's rare that I go a whole month without eating something that is coming out of a Quattro Stagioni jar. The one-piece lids are indeed very handy, even if they are a bit pricey (but you probably already noticed that).
All of the Bormioli material (website) and instructions (I'm reading them now from the lid packaging) only mention canning with boiling (pasteurization to be precise), and I've only seen them used that way. This restricts the type of foods you can can (pun not intended) to highly-acidic ones: fruit conserves, tomato sauces, pickled vegetables, etc.
Of course, for maximum hygiene you should follow the instructions to the letter, and use a new cap every time. However, I've seen people successfully re-use caps for canning with less spoil-prone foods (e.g. pickled vegetables), but this is anedoctal and I don't think I can really suggest it.
The lid packaging also report a toll-free number “grandmother Amelia info” (not joking), but unfortunately it's late now as I write; I might call next Monday if I have time.
Happy canning!
If the jars are properly sealed the vacuum in the jar and the waxed edge will hold the lid safely sealed. Undisturbed those jars will remain sealed until they are opened. The ring will reduce the risk of "unintentional" opening and that is really all the ring does. There are two real advantages to removing the ring once the seal is set.
- If something spoils in the jar it is likely to pop the lid open. Spoilage would give off gasses that would increase the pressure inside the jar and break the seal. This is more obvious if the ring has been removed.
- When it comes to juices, unintended fermentation is an issue. Even if raised to a temperature that is expected to kill yeast sometimes some of the little buggers get through and will ferment juices. Without the ring the fermentation breaks the seal. This prevents jars from exploding under pressure (yes, it can happen). I had a grandmother who would can grape juice, but did not want 'wine'. When the lids popped it identified the jars that had fermented, and which could be disposed (sometimes not the way grandma intended).
I prefer to leave the rings on as when the jars get stacked up in the pantry jars can get jostled and a lid may get accidentally opened, but there is nothing "wrong" with taking them off.
Best Answer
That means the jars have been sealed, however it’s just one of the safety measures of pressure canning. The other function of pressure canning is to kill the pathogens by exposing the food to high temperatures for a certain time. You should complete the full process to achieve food-safety.