I am on the point of jarring up a batch of lovely marmalade. The oranges have been in the freezer for almost 2 years, I think.
Edit: and I think it's slightly on the runny side, although it hasn't finished cooling yet. I normally end up with between 11 & 12 jars, but today I've ended up with a little over 12. It could have done with a bit longer boiling. However, every pot has sucked down the lid's vacuum button, so it should be safe from living things that can't open lids eating it.