The Slowcook at Spydog Farm The Slowcook at Spydog Farm

Canning, Interrupted

July 29th, 2009 · 2 Comments · Posted in garden, Recipes

There's more than one way to can a tomato

There's more than one way to can a tomato

Do you set aside a day to can tomatoes?

I know I don’t. If I spent a day canning tomatoes, we’d have enough canned tomatoes to feed an army. We’ve found that just two healthy Roma tomato plants provide enough tomatoes to last us the entire year. In fact, we just used the last pint of diced tomatoes from last year.

This presents a bit of a problem, inasmuch as the tomatoes don’t all ripen at the same time. Every day we find two or three or four. I harvest the nearly ripe ones (before the squirrels can eat them) and start a collection in a bowl in the kitchen. When the bowl is full, I start canning.

We started a massive home improvement project recently, which presents a second problem. My time is often short these days. So I wasn’t even able to finish canning the first batch I started. Instead, I went ahead and peeled the tomatoes from my bowl–immersing them in boiling water for 20 seconds, then cooling them off in cold water. The skins slip off fairly easily. Then I put them in the refrigerator overnight until I had a few spare minutes to finish the job.

The next morning, I placed six pint jars in a 250-degree oven to sterilize them. While they were in the oven, I brought a big pot of water–my pasta cooker with the strainer insert–to a boil. Meanwhile, I began cutting my tomatoes into 1/2-inch dice. When the tomatoes are all cut, place them in a heavy pot and bring to a boil. Lower heat and cook gently for 5 minutes.

By this time, your big pot of water should be boiling. You are ready to can and process the tomatoes. Be sure to use new lids. They have a bit of adhesive around the edge that creates the tight seal you need to keep oxygen–and dangerous pathogens–away from your tomatoes.

Most vegetables need to be processed under pressure in order to build the heat needed to kill any germs that might be lurking in the jars. (Not that I would really know. The only vegetable canning I’ve done is with tomatoes.)  Tomatoes have just enough acid–about 4.6 on the pH scale–that they can be processed without pressure. The acid keeps germs away. But just to be on the safe side, we add 1 tablespoon fresh lemon juice and 1/2 teaspoon salt to each pint on tomatoes.

While the tomatoes are still hot, ladle them into your sterilized pint jars. Use a chop stick to stir in the lemon juice and salt. and remove any air bubbles. Screw on the lids and use your jar lifter to lower the jars into your processing pot. The water should come 1 inch over the tops of the jars at least (they make special canning pots for this). Maintain a slow boil and process the canned tomatoes for 30 minutes. Then lift the jars out of the water and place them on a wire rack to cool.

I wasn’t sure how many jars I would get from my most recent collection of Roma tomatoes. I thought it might be six pints. I was wrong. It was only three. But guess what? The plants are loaded with more tomatoes. There’s definitely more tomato canning in my future. And eventually we’ll have enough of our own diced tomatoes–grown right here in our kitchen garden in the District of Columbia, about a mile from the White House–that we’ll never have to buy any at the store.

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  • Brett

    Nice write-up Ed! I’ve mentioned my tomato plight before but there’s a local stand about a mile from me that sells bruised ones very inexpensively. I’ll have to give this a go.

  • Daisy

    You can sterilize the jars by heating in an oven? I did not know that. Sounds much easier than boiling them, and less likely to crack due to bouncing around in boiling water.