Unless there were added ingredients like lemon juice, and I have no idea how much it would take, I can't see canning it BWB because watermelon has a pH of 5.18-5.60. So it's not an acidic fruit like apples. The limit for BWB is 4.6 or lower.

The other concern is one of flavor. I'm not sure how much flavor would survive the canning process.

Just a guess. I'll do a little searching in my sources and see if I come up with anything.

Carol

Thanks Carol, that was kind of what I thought. I was canning some peaches tonight, so I canned the peaches in a syrup of watermelon juice, grape juice, and lime juice. I did find an old text file about preserving food that said watermelon's pH was too high for plain BWB canning. So I canned some watermelon juice with the remnants of grape & lime juice (and a few bits of peaches) and a LOT of extra lime juice (used 6 big limes) to can 6 quarts of mostly watermelon juice.

I get all those food parts free, so the only loss if it comes out funny is lids, my time, and the electricity for the stove. I used to be a chemistry teacher, so you'd think I could calculate the pH of my mixture, but I didn't measure precisely and I really don't remember how to do that anyway. Later this winter I can report back on how canned watermelon juice (with lots of lime) tastes. I plan to put it into fruit smoothies, and I like lime in my smoothies, so that part should be okay, it is more the boiling of the watermelon that concerns me tastewise.

Marcia

I wonder if you could pressure can it like you would stock?

I thought about making watermelon jelly (there is a recipe in the new ball book that uses a little vinegar and some lemon grass) but I ended up just freezing the juice and using it for watermelon margaritas. I had put the watermelon through a strainer to make the juice. One of the containers that I thawed sat around long enough that the pulp settled down at the bottom. I poured off about half the liquid on the top. It had a more flavor that way.

No, it is too alkaline.

I canned it with lots of lime juice in it. It doesn't taste very good, though. :-P Live and learn!