All good advice. Want to add a test. I started doing this when making banana chips. I think I read it in one of the Ball books. When you think a batch is done, let them cool and then put them into a pint mason jar, lid on set them aside upside down. If you see any condensation by next morning, they are not done. I store things in mason jars, so it is not much of a bother. If there is no condensation, I flip them over, drop in an O2 eater, close it up and wait for that ting when the top gets sucked down from the O2 eater. I think the O2 eater is a bit extreme for things you are going to consume within the year, but have had three year old banana chips come out tasting fresh.
Oh, and I -think- the O2 eaters suck up any moisture that might be left. Something about the chemical reaction to eliminate the O2.