A pressure canner makes it easy to preserve a bounty of winter squash, but zucchini, yellow and other summer squashes are no longer recommended for canning, even with a pressure canner, because of the potential for foodborne illness. On the bright side, pickling winter or summer squash eliminates the need for a pressure canner, making the water bath method of preserving these tangy treats safe for any squash variety.
Can-Dos and Don'ts
Like most vegetables, summer and winter squash varieties are low-acid foods. In practical terms, that means they don't have the protective acidic content to makes water bath canning (also known as non-pressure canning) safe from bacterial contamination. Pumpkins and other winter squash need to be processed in a pressure canner. As for zucchini and yellow summer squash, the National Center for Home Preservation now cautions against any kind of canning. The timing of summer squash varies greatly from batch to batch, making it difficult to determine the amount of time needed to pressure-can it safely. However, summer squash in the high acidity of a vinegar brine can be preserved.
Summer Bounty Pickles
Vary the cut of your summer squash pickles to suit your mood -- peeled and cubed to go into antipasto dishes, or unpeeled and sliced into rounds or spears, to use as you might cucumber pickles. The pickles will be crispier if you generously salt them, then add ice cubes on top, and leave them for 3 hours before draining. This draws water out of the summer squash. Add some optional onions or red peppers to liven up the mixture, if desired. The pickling liquid should consist of about 2 parts water, 1 part vinegar and an optional 1 part sugar; however, you can adjust the proportions a little to amp up the tartness or sweetness. But start with a credible recipe designed specifically for summer squash. Season the brine with spices such as dry mustard, turmeric and ginger or stick with a few dill sprigs for each jar.
Autumn Harvest Pickles
Pumpkins and other winter squash types also take well to pickling for use as a fruity-tangy side dish. Traditionally, winter squash pieces, especially pumpkins, are pickled with baking spices. Make the canning brine with equal parts white or cider vinegar and sugar. Boil that with a few cinnamon sticks, a handful of whole allspice and whole cloves, along with the zest of a lemon. Make enough of the sugary-spicy vinegar liquid to cover the amount of cubed, peeled pumpkins you'll be boiling.
After the pickling liquid boils gently for about 10 minutes, it's time to add your summer or winter squash. Add cubed, peeled pumpkin or winter squash chunks, and boil them with the liquid for about 3 minutes. After adding summer squash spears or chips to the pickling liquid, simmer them for about 5 minutes. Cooking times vary, depending in part on whether the summer squash is peeled or unpeeled. You may even prefer to place softer squash such as zucchini into the jar and then pour the boiling cooking liquid over top. Alternatively, for crispier squash, briefly add the vegetables to the boiling cooking liquid before pulling the pot from the heat and transferring the contents to jars.
The water bath method is sufficient for putting up jars of pickled summer or winter squash. It's important that the jars, lids and lid closures be sterilized in just-boiled or boiling water for about 10 minutes. Place your squash mixture and its vinegar liquid into the clean jar and leave about 1/2-inch to 1-inch of space below the rim. Wipe the rims to remove any food or liquid that may later gather bacteria, and then set the clean lids onto the jars and secure them by screwing on the rings.
Place the jars in a large pot of boiling water which has a circular rack on the bottom to prevent the glass jars from touching the hot bottom. After you've covered the pot, boil the jars of pickles for at least 5 minutes before turning off the heat and removing the lid from the pot. The jars can be removed in 5 minutes, then cooled. Some sources, such as the Colorado State University, recommend processing the jars for 15 to 20 minutes if you live at a high elevation.