Winter squash keeps well for several months in cold storage, but canning and freezing helps us enjoy them any time of year.
Because the growing conditions for squash create the perfect environment for surface bacteria, it is necessary to wash the squash thoroughly before taking a knife through the skin. Scrub squash with a vegetable brush under cool running water before cutting and cooking. Do not use soap or detergent.
Freezing squash
To freeze squash as a puree or sauce, cook it in boiling water until it’s soft. It may also be steamed, cooked in a pressure cooker or baked in an oven. Remove the pulp from the rind and mash. For a smoother sauce, put it through a food mill, blender or food processor. Spaghetti squash does not need to be mashed. To cool, place the pan that contains the squash in cold water, stirring occasionally. Freeze the squash in amounts that are easily used for recipes, using rigid plastic containers or freezer jars and leaving headspace for expansion.
Squash also can be packed in zip-close freezer bags. Be sure that any excess air is removed and place the bags of squash flat on a tray to freeze. They’ll be easier to stack when they’re frozen this way and will thaw more quickly, as well. An easy way to remove thawed squash from a freezer bag is to clip a corner and push the puree out as you would from a frosting bag.
Some stir-fry and skillet recipes and casseroles call for cubes of butternut squash. Blanch washed and peeled cubes of raw squash for 3 minutes — just until heated through — then drain and chill them in cold water. Keep the blanched cubes in a colander while chilling to prevent them from breaking apart. Drain the squash cubes thoroughly and spread them in a single layer on trays. Freeze the squash. When the cubes are completely frozen, put them in freezer bags or containers. The frozen cubes can be added directly to your recipe.
Canning squash
Because winter squash are low-acid foods, the only safe canning method is pressure canning. Cut the peeled product into 1-inch cubes, and add them to boiling water; cook them for 2 minutes, and then pack the hot cubes into hot jars; and fill the jars with boiling hot cooking liquid. Allow 1 inch of headspace. Process at 11 pounds pressure in a dial gauge pressure canner, or at 10 pounds pressure in a weighted gauge pressure canner. Process pints for 55 minutes and quarts for 90 minutes. Do not can mashed or pureed pumpkin, because the puree is too dense for heat to adequately penetrate the jar during processing. Spaghetti squash is not suitable for canning.
Source: National Center for Home Food Preservation
Go to MU Extension's Food Preservation program for more home food preservation tips.