This time of year, a canner’s fancy turns to pumpkins. Tis the season for all things round, orange and squashy, after all. However, as you start searching for recipes for home canned pumpkin butter from reputable sources, you’re going to find yourself disappointed. You see, both the USDA and the National Center for Home Food Preservation are going to tell you the same thing. Don’t do it.
I’m sure there are more than a few of you out there saying to yourself, “but I’ve been making and water bath canning pumpkin butter for years!” And it’s true, many years ago, there were USDA-approved recipes for pumpkin butter. Unfortunately, the rules of canning are not a static canon and so, in 1989 the USDA changed their recommendations and the NCHFP followed suit. No home canning for pumpkin butter, not even in a pressure canner.
The reasons why homemade pumpkin butter isn’t recommended are several. When cooked down into a butter, pumpkin flesh becomes quite dense, making it difficult for the heat produced in a canner to penetrate fully through the contents of the jar. This means that even in a pressure canner, the interior of the jar may not reach the 240 degrees needed to kill those pesky botulism spores.
Additionally, pumpkin and all other winter squash are a low-acid vegetables, meaning that without careful treatment, they could potentially be a friendly environment in which botulism spores might grow into their toxic adult state. In tests, it’s been found that the pH of pumpkin has a fairly wide range, meaning that it’s not possible to offer a basic acidification ratio as there is for other borderline and low acid foods.
The good news is that pumpkin butter can be frozen and also keeps quite well in the fridge, so it doesn’t have to be entirely off the menu. I’ve also been pondering whether one could make a an apple-pumpkin butter that would be high enough in acid to be safe for canning, but would contain enough pumpkin to be sufficiently autumnal. I may do a bit of playing around, to see if I can get somewhere close to the flavor I’d like to eat.
If you’re curious to read more about the safety hazards of canning pumpkin butter and other squash purees, click here to download the PDF that was the primary source for this post.