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helius_gw

Reasons for excluding dairy/starches in pressure canning recipes?

helius
15 years ago

I've been reading up on the do's and do-not's when it comes to pressure canning, and am just mystified by some of the rules. According to the National Center for Home Food Preservation, we are not to add thickeners to soups, such as flour, milk, cream, or pasta. Someone on this board also cautioned against adding butter to a recipe.

So... why no starch and dairy when pressure canning? I'm not looking to "weasel" out of these rules, but I'd love to know the reason/reasoning behind them. Thanks!

-Tom

Comments (2)

  • readinglady
    15 years ago

    Thickeners increase the density and that affects heat penetration. Most recipes are tested without thickeners and there's no way to know (no "formula") for the amount of additional time necessary if thickeners were added.

    From a practical standpoint, most thickeners also tend to break down in processing or through time on the shelf. It's not particularly appealing to look at a "curdled" jar of product.

    There are a few tested recipes for thickened products, but they fall into very limited categories. Pie fillings can be thickened, but only with ClearJel, which is a special modified food starch. It doesn't break down and doesn't present the same heat penetration problems as thickeners like flour. However, only in tested recipes has a sufficient processing time been determined. ClearJel is no exception to that rule.

    You will see a mustard pickle thickened with flour still "out there" in some current publications, but I've also an updated mustard pickle recipe with ClearJel, so I'm assuming over time those few recipes will be changed and flour will be eliminated totally.

    Butter and other fats insulate botulism spores, preventing heat penetration. In other words, fat increases the odds that botulism spores will survive. You can see the problem with that. Again, some few recipes are exceptions. For example, you can process salmon, which is high in natural fats. But the processing time is very long to compensate.

    There are also a few marinated pepper recipes which contain oil. But as tested they have very high levels of acid. Botulism spores like a low-acid environment, so the high levels of acid compensate for the insulating effects of the fat. And of course, there's still the heat processing.

    Carol

  • ksrogers
    15 years ago

    The ONLY starch that is stable enough for use in home canning is the Clear Jel. Its used mostly for high acid foods like pie fillings, or for making mustard pickles. There is also a thickener called Freezer Flow that I use for making gravy for meat pies that I freeze. The Freezer Flow will not turn watery after a freezing cycle.