Originally Posted by Moosetoo
I am going to can some grape juice. Last year I used the boiling-water method in the Ball Blue Book. This year I'd like to use my pressure canner. Can I? If so, how long should it process and if not, can you tell me why.
I think the question is more like "why" use the pressure canner? It will take longer to reach pressure (even 5-psi) and cool down than just using the boiling-water canner method. And, the temperature could be excessive.
The reason "why not" - you're using too much heat which will decrease the "quality" of the final product. Commercially available grape juice (something like Welch's) is only "pasturized" (about 180-F for 10-20 minutes) to kill the natural yeast to prevent it from fermenting (turning into wine) ... not pressure canned (that's about 240-F). You don't need a pressure canner to do that ...
Other than the fact that you've got a new pressure canner and want to try it out ... why would you want to deviate from the proven recipes in the Ball Blue Book? The less heat necessary for safe canning - the better the quality (more natural the flavor).