Updated: Jan 20, 2021
Garden to Table talk. A bit of a ramble inspired by tradition, our basic human need to grow food to nourish ourselves and others, friendship, nonnas through the ages, and a late summer afternoon.
Tomatoes are many things - luscious, sweet, tart, beautiful, smooth and silky, even sexy. It is no surprise then that this beautiful fruit can also be dangerous. When it comes to putting up (canning, preserving, jarring) tomatoes, we look to the pros - the uncontested authors of the Slow Food Movement and quiet authorities on managing all things voluptuous... We look of course, to the nonnas.
Generations of Italian, Italian-American and Italian-Canadian grandmothers, charged with providing for large families year-round, using only what they grew, preserved and prepared with their own loving, cautious hands. Nonnas know about tomatoes.
From nonnas, and from their hundreds of passed-down-and-along recipes, scribbled notes and tales told around the table, we've learned how to put up tomatoes safely. Once we knew to be cautious, the science was easy: if the required acidity and pH are not achieved before processing, tomatoes and other low-acid foods like green beans, corn, beets and asparagus, can produce illnesses such as food-borne botulism. The high-heat associated with hot water canning is not sufficient to kill certain pathogens in a low-acid environment, so correcting the environment is an easy fix.
Many tomato varieties, like the meaty vine-ripened San Marzanos we love (above), are very sweet when ripe. This in turn means they generally have medium-low acid and a pH of 4.5-5.2. To safely preserve tomatoes for future use, a pH level below 4.6 must be achieved. This can be done with bottled lemon juice or vinegar - nonna almost certainly used wine vinegar. Lemon juice is my preference because you don't notice it's presence or taste, and the tomato flavour shines through. Fresh lemons are not a reliable source as sweetness and acid levels vary by variety (ie: sweet Meyer lemons). Bottled vinegar should be 5% acetic acid by volume. Salt too, should be added.
It is impossible to test every variety and batch of tomatoes before canning, so we rely on a gold-standard that seems to work across the board and ensures a neutral tomato canvas from which to work your culinary magic. For every quart of whole or crushed tomatoes, we add one teaspoon of salt (we use Sicilian sea salt) and 3 tablespoons of white wine or cider vinegar, or lemon juice. This acid-balancing, plus a slow ascent to 212F (100C) on the stovetop, and an old-school hot water bath of the extended variety, take some time to be sure, but they also take the worry. And that, as any nonna will tell you, is well worth the wait.
To Preserve Old School Tomatoes in Glass Jars
Our shopping list: Tomatoes (approximately 2.5 lbs/1.25 kilos yields one quart) of the plum, Roma, or San Marzano variety, commercially bottled lemon juice or any variety or white vinegar (5% acid), and salt. We estimate the quantity of acid required by calculating 3 tablespoons per quart. Likewise with salt, using a ratio of one teaspoon per quart. Use sterilized chip-free glass quart jars with screw rings and (new) seals.
Wash tomatoes. Remove stem, core and any blemishes. When removing black blight marks, be sure to check the flesh beneath as a small surface blight can actually contaminate an entire tomato inside. Rinse the tomatoes and compost the trimmings. We can outside rain or shine (even in power outages), using a much-loved but beat up old enamel-top canning table, set next to an outdoor sink and grill.
Set a large pot of plain water to a rolling boil. Set trimmed tomatoes to the left of the pot and three bowls to the right. The first bowl should contain 50/50 ice cubes and cold water, and the second two bowls should be empty. Working with three to six trimmed tomatoes at a time, drop fruit into boiling water and wait for up to one minute or until you see the skin crack and begin to peel away from the flesh at the cut end. (Over time you will come to know visually and by touch, when the tomatoes are sufficiently scalded; simply use a fingertip to quickly 1/4 turn tomatoes to expose submerged skin, and then press gently with your finger. If the surface tension is akin to our most delicate flesh, the tomato is ready for its ice bath)
Remove tomatoes quickly from the water and plunge them into the icewater bath. This hot/cold process is called blanching. Peel blanched tomatoes over the second bowl. The skin should fall away using just your fingers. If it does not, drop the tomato back into the boiling water for a few seconds. Note that skin sticks stubbornly to un-ripe spots, and unripe tomatoes are harder to peel. Place peeled, whole tomatoes in the third bowl. You'll develop your own rhythm. Three to six at a time works for me.
Over the years, trying different methods and making mistakes along the way, we've come to a standard three types of naked tomatoes (no basil, no spice, no olive oil added before canning) - thin, medium and chunky. The integrity of the tomatoes you put into the cooking pot, before bringing to temperature, determines what goes into the glass jar. However, every type of tomato will render and process differently, so just because we suggest you will end up with whole/chunky canned tomatoes in the end, does not mean that you will. Uncertainty is part of the fun!
On this day, whole tomatoes begat whole/chunky preserves, halved tomatoes (above) begat medium preserves, and hand-crushed tomatoes begat a thin sauce-like preserve. Most recipes using whole canned tomatoes, suggest cooking times that render the pulp completely, ultimately, so plan accordingly and be flexible regardless.
Use a heavy-bottom dutch oven or stockpot to bring the tomatoes to boil slowly under their own steam (do not add water) with the lid on. Stir very gently and only as necessary to prevent scorching. A good quality new or vintage shop enamelled pot like La Creuset or Staub should allow you to bring tomatoes to boil almost without stirring. Another trick is to use a new or vintage cast-iron griddle as a simmering plate, to displace heat evenly and prevent bottom-burn. The less disturbed your tomatoes are during heat up, the less they will break apart. The halved tomatoes shown above were brought to boil with little disturbance and remained (below the juice risen to the top), largely intact.
Hint: Mark your stockpot inside and out at each quart level, using a permanent marker. You could argue for or against marking a precious pot (our large 14-quart stainless stock pot is indeed scarred but the marks make for great memories). Marking allows you to calculate, add and thoroughly incorporate acid and salt in quantity** before canning, rather than quart-by-quart* as you fill each jar.
Fill hot, sterilized jars with hot tomatoes, using a sterilized ladle and funnel. Fill to within 1/2 inch/1.25 cm of top edge of jar - this rule is important to adhere to as it affords optimal expansion/contraction space to create safe vacuum seal (and no underwater explosions), and also ensures that food does not touch the lid of the jar during processing and storage.
If using the quart-by-quart* method of balancing, add three tablespoons of lemon juice or vinegar and one teaspoon of salt to each half-full jar, then continue filling with hot tomatoes. If using the quantity** method described above to add acid and salt during initial heating of the tomatoes, do not add anything additional as you fill the jars.
Use a sterilized rubber or plastic wand to agitate any air bubbles to the surface (do not use metal as jars can crack). Wipe top edge of glass jar with a clean lint-free cloth dipped in boiling water (re-fold and use fresh clean surface of cloth for each jar). Place hot sealing lid on clean glass surface and twist on screw-ring. Hand tighten only - do not over-tighten. *For Italian style tomatoes, add a sprig of clean and dry basil, and a glug of quality olive oil (per jar) to the hot tomatoes before adding lids and rings, but be sure to leave a lit extra space before doing so.
Process immediately in hot water bath for 50 minutes. Add filled hot jars to boiling water, gently, ensuring that jars are submerged by two inches. Begin timing when water returns to boiling. Cover and check water level occasionally. Top-up with already boiling water as needed. After 50 minutes, uncover pot and turn off heat. Let jars sit undisturbed for 10 minutes, then remove with jars with tongs and place on a cooling rack for one full-day before disturbing or labelling. Check sealing lids to ensure that the convex bumps in the centre of each lid has been sucked down to flat (slightly concave) to create an airtight seal. As jars cool, you will likely hear the telltale 'pings' that indicate success. Unsealed jars of tomatoes should be used immediately or placed in the fridge and used within a few days.
The beauty of preserved naked tomatoes, is that they are gastronomically neutral. On a whim, we can create Italian, Moroccan, Asian, Greek, Thai, Mexican or Cajun influence. Naked tomatoes can be reduced, expanded, embellished, cocktailed, filtered and otherwise fetted as you wish, without prejudice.
On this late summer day, in homage to the generations of Nonnas who inspired and keep us safe, we stayed as close to home as we could. A simple week-day Sunday sauce of sorts made with one jar of naked tomatoes,1/2 cup (125ml) extra virgin Olio Classico from Domenica Fiore, 1 clove of garlic, crushed, a 1/2 teaspoon red chili flakes, and a pinch of sea salt. **Chef tip: Just before your pasta of choice (we suggest pappardelle) is cooked al dente in salted water, set aside 1/2 cup or so of the starchy pasta water, drain the pasta well and add it to the tomato sauce. Let the still thirsty noodles 'drink in' the sauce as they make their final run for the finish (a minute or two) then add in the pasta water and bring it all to heat again to thicken, then you are done. Well, almost. Once plated, garnish with torn fresh basil leaves if you have, plus grated or shaved parmesan or pecorino cheese. Big, big love nonna!
This blog post is based on personal experience and successes to date. Preserving tomatoes and other fruits and vegetables requires careful research and planning, and the published rules and recommendations change frequently and with varying altitude (literally). Always check The USDA National Center for Home Food Preservation or Canada's Home Canning Safety Recommendations before proceeding with this or any home preserving or home canning project.