PRESERVING YOUR LATE-SUMMER TOMATO HARVEST

One of my favorite books about food (and life in general) is Animal, Vegetable, Miracle published in 2007. I loved author Barbara Kingsolver’s account of her experiences in self-sufficient living on her Virginia homestead, but it was her chapter about tomatoes that really got me. In it, she describes what it was like to process a year’s supply of homegrown tomatoes for her family of four during the hottest month of the year. Factoring in the chilis, homemade pizzas, minestrone soups, and pasta dishes they all loved, the hundreds of jars of tomatoes she put down that August made complete sense. These jars became the basis for the rural equivalent of fast food: quick and inexpensive dishes that are healthful, as well as delicious.

No one will blame you for scaling down your tomato-canning activities to a more manageable level, especially if you hope to leave your kitchen this month. Maybe you’ve grown a few more tomatoes than you can eat fresh from the vine, or you’ve found some plump and tempting specimens at your local farmers’ market. So what varieties work best for canning?

Plum or paste varieties such as San Marzano, Amish Paste, Principe Borghese and Opalka contain less water and fewer seeds than their pincushion-sized cousins and are the ones most home preservers prefer, although some say they have less flavor than larger tomatoes. It’s a bit of a trade-off: I love the richness of a fresh Brandywine and Cherokee Purple tomato, but canning these varieties has left me with jars three-quarters full of water and seeds. And while cherry varieties such as Sungold or Sweet Million can be successfully roasted or dehydrated for use in salads or as pizza toppings, canning them leaves you with more skins and seeds than flesh.

When it comes to peeling tomatoes before canning them, people’s opinions vary. Many can’t be bothered with the extra step of removing the skins, but I’m not fond of the tough, papery strands that accumulate in my jars when I skip the peeling step. An Italian-style tomato press that efficiently squeezes out the skins and seeds of blanched tomatoes makes the job easier and turns them instantly into sauce. Give your fresh tomatoes a 5 – 10 minute dip in boiling water, followed by another 5 – 10 minute plunge into a bowl of ice water. The sauce that emerges from plum tomatoes that have been run through a press is thick and can be used as is to top pasta, or you can add fresh basil or chopped shallots to it for a more intense flavor. If your sauce is a bit thin, boil it in an uncovered saucepan to reduce it until the desired thickness is reached.

Got a few too many tomatoes to process? Just pop them into the freezer – no blanching needed. The skins will come off easily after thawing and the thawed fruit will taste much like canned whole tomatoes.

Canning Safety

Whether you opt to can your tomatoes whole or to turn them into a sauce, you must not forget to add extra acidity. While tomatoes are naturally acidic, some varieties do have a lower acid content, making them a riskier prospect for canners. By adding extra acidity in the form of bottled lemon juice or powered citric acid, you lower the pH level, which will prevent the harmful botulism bacterium from proliferating inside the sealed jar.

DIY Canned Whole Tomatoes or Sauce

Use whatever amount of tomatoes you have on hand. For paste varieties, I’ve found that 5 – 6 tomatoes will fill a 500ml jar.

Peel your tomatoes using the blanching method: 5 minutes of immersion in boiling water followed by another 5 minutes of immersion in ice water. After removing the tomatoes from the pot of boiling water, keep that water boiling. If you are making sauce with a tomato press, run the tomatoes through it several times to extract all the pulp and juice from the skins.

Pack whole tomatoes or sauce in clean jars, leaving 1cm of headspace in each jar. Add extra acid to each jar to ensure food safety: 15ml lemon juice per 500ml jar (or 2 grams citric acid). Add lids and seal.

Put jars in pot of boiling water, making sure they’re covered by the water. (Immersing the room temperature jars into the boiling water will lower its temperature.) When the water returns to a boil, start timing. Leave jars in boiling water for 45 minutes and then allow them to cool.

Canned tomatoes should keep for up to a year on the shelf with no change in flavor, though some home canners keep them for much longer.

Make sure to listen for the pop when you break the seal on the lid to open the jar. No pop means the jar did not seal and its contents should be discarded.

Note: Adding herbs and vegetables such as peppers and mushrooms to your tomato sauce before canning it will lower the acidity of the product and is not safe to do. If you want to experiment this way, you can freeze your sauce instead of canning it, or preserve plain tomato sauce and add other ingredients after the jar has been opened and is about to be consumed.

Elizabeth Peirce

Elizabeth Peirce is an award-winning author, editor, gardener and teacher. Her book You Can Too! Canning, Pickling, and Preserving the Maritime Harvest is available from Nimbus Publishing and at all major bookstores. Her new book Grow Hope: A Simple Guide to Creating Your Own Food Garden At Home was released in early 2021. Elizabeth offers workshops that focus on how to grow and preserve our own food and she is hard at work on an online course called "Gardening in Tough Times." Visit her website at elizabethpeirce.ca.