I made 12 jars of blackberry jam, and there is now a white residue on the outside of the jars. I am guessing it's mineral deposits from hard water, and I read that one can add vinegar or lemon juice to deal with this. I did not add either of these - only the berries, sugar, and pectin as the recipe called for. I boiled the jars in the water bath prior to filling them, so this deposit would have been inside the jars as well and is now in the jam. I know mineral deposits from hard water contain calcium, which can raise the pH. Does this mean the jam won't keep? Must it all be eaten right away? Can I re-process it, and add vinegar or lemon juice? It would be a shame for all those berries to go to waste! Thanks for any advice.