If you are like me, you love this time of year because it means that Halloween is just round the corner! All jest aside, there are some pretty serious concerns regarding canning pumpkins and these concerns shouldn’t be taken lightly. Both the USDA and the National Center for Home Food Preservation advise that this should never be done.
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.