You may be able to mix it with some cooked tomatoes and seasonings and freeze it as ratatouille, or cook it into a sauce. Again, only if it has been less than 24 hours.

When it comes to exposed foods in the jars it is usually caused by siphoning of liquid out of the jars. That is caused by sudden changes in the internal pressure in the canner either during processing by rapid adjustments of the heat level or improper cool down procedures. Both issues should be avoided.

Generally speaking the food above the liquid is considered safe to eat but it will discolor and darken and appear unappealing. In this particular case the risk of safety is undermined by the fact that it is summer squash.

Personally I wouldn't keep the squash - too many concerns for me - but the choice is yours.

Dave

PS: you might want to review the step-by-step instructions on how to use a pressure canner at NCHFP. It is very helpful.

Why is canning summer squash or zucchini not recommended?

Recommendations for canning summer squashes, including zucchini, that appeared in former editions of So Easy to Preserve or USDA bulletins have been withdrawn due to uncertainty about the determination of processing times. Squashes are low-acid vegetables and require pressure canning for a known period of time that will destroy the bacteria that cause botulism. Documentation for the previous processing times cannot be found, and reports that are available do not support the old process. Slices or cubes of cooked summer squash will get quite soft and pack tightly into the jars. The amount of squash filled into a jar will affect the heating pattern in that jar. It is best to freeze summer squashes or pickle them for canning, but they may also be dried. NCHFP

There are some few mixed vegetable formulations that allow the inclusion of squash. Mixed vegetables and tomatoes with okra or zucchini are two.

The chart at the link provides several reasons for loss of liquid from jars.

Carol