There are two rules of thumb for pressure canning mixed vegetables. One, chop the vegetables into pieces of uniform size, so that they heat and cook evenly. And two, put whatever grab-bag of vegetables you want into the mix, but set your timer for the vegetable that takes the longest time to safely can.
Examples, all in quarts: If you're canning a mix of potatoes (40 minutes), green beans (25 minutes), and carrots (30 minutes), then bring the canner up to pressure and keep it there for 40 minutes. If you're canning a mix of potatoes, green beans, carrots, onions, zucchini, tomatoes, and whole-kernel corn (maize) -- I told you it was a grab-bag -- then it needs to process for the time it'll take to safely deal with the corn, which is 85 minutes.
But it's a little more complicated than just that rule of thumb. You also have to take into account that, when you pack chopped, mixed vegetables into a jar, the product is more compact than it would be if it were just one type of vegetable. To illustrate, when you pack asparagus into a jar, you stand the spears upright and slide them in like a packet of pencils; but when you chop them more finely and add other stuff to the mix, you get more mass in the jar. (Think BB's or ball bearings, versus marbles.) And thus it will take more time to heat the jar through. So the National Center for Home Food Preservation adds an extra 5 minutes to its own instructions for mixed vegetables, even though no single ingredient, individually, requires more than 85 minutes to process.
As I've mentioned before, I don't like to argue with science. So while my instinct said, "85 minutes," my hands said, "90 minutes," and I sure did heat up my kitchen that day. According to Facebook:
And the result:
4:12 p.m.: Off to run a significant percentage of CSA veg thru the pressure canner. See you on the flip side.
4:58 p.m.: OK, 4 quarts of mixed CSA vegetables for soup in the canner, set to process for 90 minutes because I included sweet corn. At least it's not too hot today.
6:35 p.m.: Stupid corn. It's a million degrees in here now!
|Photo taken with my antiquephone: sweet corn, carrots, green beans,|
zucchini, onion, and tomatoes
Each quart jar there will make for a very quick soup this winter: add water or broth, heat to boiling, and add cooked pasta or rice. Sprinkle parmesan on top or serve a little cheese on the side, throw some bread or rolls on the table, and that will warm you up in November or February. I'll get three if not four portions of soup out of each of those jars. Looking forward to it already!