All about the pumpkin: From canned pumpkin shortages to pureeing

Q: Is there a canned pumpkin shortage again this year?

A: You’re not the only one asking that question! Karen Blakeslee, K-State rapid response coordinator, shared information that just came out from written by Jay Sjerven addressing the topic. The article states “Home bakers should find plenty of canned pumpkin on grocery shelves for the holiday season. Pumpkin production has rebounded from last year’s weather-reduced level.

“The U.S. Department of Agriculture officially estimates pumpkin production only after a year ends. But asked what pumpkin watchers might expect this year, an analyst for the USDA’s Economic Research Service, based on expectations for at least three-year average yields and three-year average acreage, preliminarily estimated pumpkin production would be up 13% from 2009 and mark a return to more normal levels.

“Last year, pumpkin production was reduced because of lousy weather during both planting and harvesting. Much of the crop was planted late, and heavy rains that persisted during the harvest prevented many pumpkins from being picked and processed. The result was canned pumpkin supplies during the holiday season last year were limited and supplies after the season dried up altogether.

“Growing conditions this year weren’t great. Again there was rainy weather during the planting season, and a rapid turn to hot and dry weather in July and August in principal growing areas, especially Illinois where over 90% of pumpkin for canning is grown, pushed the crop to mature earlier than was optimal. The result may be a crop of middling quality. But harvest weather has been outstanding, allowing producers to maximize their out turn.”

Q: How do I can pureed pumpkin?

A: Home canning pumpkin butter or mashed or pureed pumpkin is NOT recommended. In the USDA’s Complete Guide to Home Canning, the only directions for canning pumpkin and winter squash are for cubed flesh. In fact, the directions for preparing the product include the statement, "Caution: Do not mash or puree.”

There is not sufficient data available to allow establishing safe processing times for any of these types of products. It is true that previous USDA recommendations had directions for canning mashed winter squash, but the USDA withdrew those recommendations and any publications preceding the “Complete Guide to Home Canning” (September 1994) are considered out of date.

Some of the factors that are critical to the safety of canned pumpkin products are the viscosity (thickness), the acidity and the water activity. Studies conducted at the University of Minnesota in the 1970s indicated that there was too much variation in viscosity among different batches of prepared pumpkin purees to permit calculation of a single processing recommendation that would cover the potential variation among products. Pumpkin and winter squash are low-acid foods (pH > 4.6) capable of supporting the growth of Clostridium botulinum bacteria, which can cause the very serious illness botulism under the right storage conditions. If the bacteria are present and survive processing, and the product has a high enough water activity, they can thrive and produce toxin in the product.

More recent research with pumpkin butter has been done at the University of Missouri.

Pumpkin butter is mashed or pureed pumpkin that has had large quantities of sugar added to it, but not always enough to inhibit pathogens. Sometimes an ingredient such as vinegar or lemon juice is added to the formulation to increase the acidity (decrease the pH). However, pumpkin butters produced by home canners and small commercial processors in Missouri have had pH values as high as 5.4. In fact, the pH values seemed to be extremely variable between batches made by the same formulation.

It is not possible at this point to evaluate a recipe for pumpkin or mashed squash for canning potential by looking at it. At this point, research seems to indicate variability of the products is great, and in several ways that raise safety concerns. It is best to freeze pumpkin butters or mashed squash.

Q: How do you freeze pumpkin?

A: Select full-colored, mature pumpkin with fine texture (not stringy or dry). Wash, cut into cooking-sized sections and remove seeds. Cook until soft in boiling water, in steam, in a pressure cooker, or in an oven. Remove pulp from rind and mash. To cool, place pan containing pumpkin in cold water and stir occasionally. Pack into rigid containers leaving headspace, and freeze.

Pumpkin also makes excellent dried vegetable leather. Here’s one recipe for making pumpkin leather: If you do not have access to a dehydrator and want to learn more about drying foods, contact me about checking out the food dehydrator that we have available for educational purposes only at K-State Research & Extension in Douglas County.

Pumpkin Leather

2 cups canned pumpkin or 2 cups fresh pumpkin, cooked and puréed

1/2 cup honey

1/4 teaspoon cinnamon

1/8 teaspoon nutmeg

1/8 teaspoon powdered cloves

Blend ingredients well. Spread on tray or cookie sheet lined with plastic wrap. Dry at 140 degrees.

Q: Can pumpkin be pickled?

A: Pumpkin can be used in pickled recipes such as salsas, chutneys, and relishes; however, your recipes for these must be treated as freshly prepared foods and kept refrigerated. We do not have tested recipes and procedures to recommend for safely canning these types of products by either the boiling water or pressure canning method.

— Susan Krumm is an Extension agent in family and consumer sciences with K-State Research and Extension-Douglas County, 2110 Harper St. She can be reached at 843-7058.


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