Preserving Pumpkin Purée Safely at Home

Every fall, it seems more and more pumpkin food products appear on the market. Pumpkins are a member of the winter squash family. Commercially produced "puréed pumpkin" can consist of a type or blend of several different winter squash varieties, with those most commonly used being Hubbard, Golden Delicious, and Butternut.

Pumpkin or squash purée can be made at home and preserved by freezing for future use. However, if you are looking to can pumpkin or squash at home, the only safe option is to pressure-can cubed squash. Do not can mashed, puréed, or grated squash or pumpkin via pressure or boiling water bath. There are no research-tested pressure canning recipes for puréed pumpkin that prove the amount of heat penetration into the center of the product is adequate to eliminate the risk of Clostridium botulinum, which can cause botulism toxin and be deadly.

When making purée at home, sugar pumpkins and pie pumpkins are the winter squash varieties commonly used. You can also purée other types of winter squash. Butternut, Hubbard, Golden Delicious, and neck pumpkins all tend to be sweet and less stringy. Purée may be preserved by freezing, but should be limited to no more than 2 pounds of food per cubic foot of freezer capacity per day.

To make purée, choose mature pie pumpkins—or squash—with firm rinds. The National Center for Home Food Preservation (n.d.) webpage and the book "So Easy to Preserve," (2020) by Andress, E.L. & Harrison, J.A. outline the following method: wash the produce, remove the pulp and seeds, and then cut it into easy-to-use cooking-sized slices or chunks. Cooking may be done by boiling pumpkin in just enough water to prevent sticking. Or it can be done by steaming or baking pumpkin, covered, in the oven until soft, or by cooking it in a pressure cooker.

When the slices or chunks are soft, cool them slightly and scrape the inside from the rind; then mash or purée the squash in a bowl. To cool the purée, place the bowl in cold water. Stir the purée periodically. For freezing, package the cooled purée in rigid freezer containers, leaving ½ inch of headspace. Seal the container and freeze. Squash purée may also be put into zip-close freezer bags; squeeze excess air out of the bags and then flatten them onto cookie sheets and freeze until solid.  Once the packs of purée are frozen solid, stack them for more efficient storage.

Penn State Extension's "Let's Preserve: Squash and Pumpkins" fact sheet states that squash may also be cubed and frozen by blanching the cubes in boiling water for approximately 3 minutes (i.e., just until heated through; Reed et al., 2021). Then, drain the cubes in a colander. Chill the cubes in cold water in a colander to prevent the cubes from falling apart. Remove excess moisture from chilled cubes by patting them with a paper towel. Spread the cubes on a cookie sheet in a single layer. Place the cookie sheet in the freezer for at least 4 hours. Transfer the cubes to freezer bags and press out excess air before freezing. This method allows you to make purée fresh or to use the cubes in soups, casseroles, or stir-fries.

If you want more information on preserving summer and winter squash, additional instructions can be found in the "Let's Preserve: Squash and Pumpkins" (2021) fact sheet.

Here is a yummy fall soup that uses butternut squash.

Lentils, Butternut Squash, and White Bean Soup 

6 servings | Serving size: ⅙ of recipe

When preparing this recipe, start with clean countertops and utensils. Wash hands with soap and water. Wash whole, fresh produce under cold, running water by rinsing lentils and parsley, gently rubbing onion and garlic, and scrubbing butternut squash with a clean vegetable brush.  Prewashed packaged items do not require further washing. 

Ingredients

• 1 Tablespoon olive oil
• 1 yellow onion, diced
• 2 cloves garlic, minced
• 4 cups peeled and cubed butternut squash (fresh or frozen)
• 8 cups no-salt-added vegetable or chicken broth 
• 1½ cups dry green or brown lentils, sorted
• 1 teaspoon ground black pepper
• 1 teaspoon dried thyme
• 2 bay leaves
• 1 (15 ounce) can unsalted white beans, drained and rinsed
• ¼ cup minced fresh parsley or 2 Tablespoons dried

Directions

1. In a large pot, heat the olive oil over medium heat. Add the onion and cook for about 5 minutes.
2. Add the garlic, and cook for 1 additional minute. Add the butternut squash and cook 2–3 minutes. Add the broth, lentils, black pepper, thyme, and bay leaves.
3. Bring to a boil, then reduce heat. Cover and simmer for 35 minutes. Remove bay leaves.
4. Add the white beans and parsley, cook for 5 minutes.

*Please Note: This recipe is not suitable for canning and should be stored in the refrigerator. 

Recipe adapted from Oldways.

Sources 

1. Andress, E. L. & Harrison, J.A. (2020). So Easy to Preserve. University of Georgia Cooperative Extension. 
2. National Center for Home Food Preservation. (n.d.). Freezing Pumpkin. University of Georgia. 
3. Reed, S. L., Zepp, M. J., Laborde, L. F. & Hirneisen, A. J. (2021). Let's Preserve Squash and Pumpkins. Penn State Extension.