My mom has been making "instant gape juice" for as long as I can remember.
You can find this method in canning books dating at least back to the 1930's
if I recall right.
We always process quarts 10 minutes in a hot water bath. Never have to
worry about lids not sealing properly nor spoilage.
Mark Krejci
[NAFEX] instant grape juice,
Mark Krejci, 11/17/2002