Thoughts on Canning Tomatoes

Students who take my canning class tell me that one of the biggest hurdles when it comes to canning is … surprise!…  time. (the other is the commendable desire not to sicken one’s family)

I will not prattle about how time used now is time saved later … and other opinions/musings/ramblings etc. I have expressed myself about food preserving in general and  canning specifically before here.

I will not give an on-line canning lesson either – that’s much better done in this nifty, detailed and clearly written USDA guide.  And here, also are the answer to a bunch of commonly asked canning questions from the same source.

But I am here to tell you that canning tomato sauce does not have to be a day-long process. Tasks can be broken down is steps that be performed over several days, with the last day being a couple of hours. Total time is somewhat longer than if done at once. But, for for me, 4 times 2 hours is more manageable than 7 hours at once.

When you have a garden, you may not have enough tomatoes ripening at the same time to make a large batch of sauce – after all it takes about 5 pounds of tomatoes to fill a quart jar with thick puree. So the 5 quart jars that fit in my canner require 25 pounds of tomatoes; 7 pints almost 20 pounds

I pick tomatoes every day or every other day. Sometimes bugs, rain, threat of storm, or just summer weather in Virginia demand that I  harvest before tomatoes are as ripe as I would like; in that case, I let them mature fully in the house, off the vine. Really, they should be as ripe as possible for canning.

Of course, I prefer the so-called canning tomatoes – a.k.a. plum, processing or paste. They have been bred for thick walls and less watery pulp. But I do use any tomatoes that I grow including colors other than red: once mixed with red tomatoes, they blend in. Although I made yellow sauce one year, I did not greatly care for it as tomato “sauce” (mostly for esthetic reason) – I loved it as soup though.

My preferred way to can tomatoes is plain sauce (really, a thick purée) with nothing added but bottled lemon juice for acidification. It’s simpler to process … and much more versatile later: I can use it for all kind of sauces with added ingredients, for lasagne, for soup, for chili, for pizza etc. Sometimes I tuck in a sprig of rosemary or a few basil leaves, but mostly I do it plain

Tomato sauce must be reduced as I want to can sauce not juice –  and it is a pain to do it over the stove. But I have developed a process that works well for me.

Every day or every other day,  I roast one or two big pans of tomatoes. If that’s all that I have in the oven, I do 2 large pans (I like to use large rimmed cookie sheets), to make sure I take advantage of the full oven capacity. If I am using the oven for something else, I’ll slip a pan of tomatoes of the other shelf.

I slightly oil the pan. Wash the  tomatoes and remove any blemished or bruised spot. Halve the plum tomatoes, quarter or eighth the beefsteaks. No need to peel, seed nor core. Line them all, cut side up, tightly packed – in a single layer – on your baking sheet. Salt. Bake.

If I have a choice, I prefer to bake them at a low temperature for several hours – 225 to 275F for a couple of hours. If I have something else in the oven, I just do it at whatever the temperature of the something else requires. But for maximum flavor, the long slow bake is best.

As they bake, tomatoes give up water which accumulates in the pan (some cooks off too, of course!). Let the tomatoes cool in the oven. When they are cooled enough to handle comfortably, lift them from the pan and put them in fine-mesh sieve placed over a bowl, and let them drip off additional water for an hour or two. Gently lift them off the sieve onto your food mill. Or if you do not have time to purée them now, trnsfer into a non-reactive containers in the fridge.

I love my food mill. Yes, food mill. That is one necessary gadget to make tomato sauce. I purchased  mine well over bought it 20 years ago for $20 ($19,99 says the label still on the box), and I would not do without it. Stainless steel and made in Italy, it’s still available today, but with inflation, it’s over twice as much now. The changeable plates are indispensable: with the finer ones, I process tomato sauce or remove seeds for berries. With the middle plate I made superb mashed potatoes; the larger one allows me to make smooth apple sauce – and, with caution, handle damson or American persimmons.

When I am ready to purée the tomato, I dump them in the food mill fitted with the fine plate. And on we go – the first few turns are quite easy. But you do have to turn that handle, and when you think you are done, keep going. There is a lot of goodness in the last bits – the more of the skin you manage to mill, the better the texture of the sauce. I do not mean, that there should be bits of kin in the sauce… that’s not really pleasant. I mean you should crank that handle: as long as it’s easy, it’s just tomato sauce. When it starts to get hard, and the stuff comes through really slowly, that’s when it gets good… and you are on your way to great sauce. Use a spatula to scrape the bottom of the mill and crank again. If something comes through (even if very little) you are not done. Keep cranking. There should be surprisingly little remaining in the mill when you are truly done.

I generally mill the day batch of slow roasted tomatoes, and refrigerate the puree. Once a week, I can. I consolidate all my puree, heat them up to gently boiling (don’t forget to stir) – and then can. I follow the USDA guidelines both for acidification and processing time.

Another very fun thing to do if you have access to large quantities of the tasty tomato, is to make single-variety tomato sauce. I can tell you that Slow Roasted Purple Cherokee tomato sauce will knock your socks off.

We have a few more weeks of tomato season ahead of us, and the weather is cooler – so canning now is a much better proposal. Have fun!