How to Can Homemade Tomato Sauce
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When it comes to home-canned food, tomato sauce reigns supreme when it comes to versatility.
I don’t know about you, but in our house we eat a lot of tomato-based dishes; Pastas with marinara or bolognese sauce, pizzas topped with homemade pizza sauce, soups and stews with tomato sauce as the base, casseroles and bakes like cabbage rolls and lasagna… The list goes on and on.
For this reason, we go through a ton of tomato sauce. And since I like to grow, preserve and prepare as much of our own food as possible, this means we grow A LOT of tomatoes, and we can A LOT of tomato sauce with those homegrown tomatoes so that we always have what we need on hand to prepare our tomato-based meals from scratch.
This basic tomato sauce recipe has just three ingredients: Tomato sauce, a little bit of salt and a splash of lemon juice (for safe preservation purposes).
I don’t typically add any herbs or spices to my home-canned tomato sauce because I can dry those herbs and then add them when I’m ready to use the sauce. This way the tomato sauce stays really neutral and versatile, so I can use it for whatever I want.
Having jars of basic tomato sauce on hand is much like having a blank painter’s canvas that you can use as a foundation to create whatever you like. You can add Italian herbs like dried basil and oregano for a pizza or pasta dish, or season the sauce with cumin and chilli powder for a Mexican-inspired dish when you’re ready to prepare a meal.
That being said, if you’d like to add some herbs to this tomato sauce, I’ve included instructions on how to do so safely, because if you do intend to can this sauce, you’ll need to stick to the tested amounts in order to ensure a safe finished product.
Water bath canning vs. pressure canning tomatoes
The general rule when it comes to home canning is that high acid foods can be canned in a boiling water bath while low acid foods MUST be canned in a pressure canner.
High acid foods include things like fruits, jams and jellies, pickles, etc.
Low acid foods include things like vegetables, meats, stocks and broths, soups, combination meals, etc.
In order to qualify as high acid, a food must have a PH of 4.6 or lower. Most high acid foods like fruits and pickles fall well under that 4.6 marker, but tomatoes tend to straddle the line between acid and non-acidic, so they are treated differently than all other fruits and vegetables when it comes to canning.
Some tomato varieties are exactly a 4.6 on the PH scale, while others are either higher or lower (making them either less acidic or more acidic).
In addition, tomatoes become less acidic the longer they’re allowed to ripen on the vine.
Since there’s no real way to know how acidic each batch of tomatoes is, they must either be acidified with lemon juice when water bath canning, or they must be pressure canned to ensure a safe final product.
That being said, even pressure canned tomatoes require the addition of bottled lemon juice (or citric acid). This is because the process for pressure canning tomatoes does not actually heat the tomatoes more than water bath canning. Rather, it offers a quicker cook time than water bath canning.
According to the USDA’s National Center for Home Food Preservation website, “There has not been a properly researched process for pressure canning of low-acid tomatoes without added acid, so the available process times still require the addition of acid as if they are being processed in boiling water.”
So whether you decide to water bath can your tomato sauce or pressure can it, you’ll need to either add lemon juice or citric acid to ensure a safe end product.
I’ve included instructions for both water bath canning and pressure canning tomato sauce so you can choose the method you prefer.
Choosing the right tomatoes for canning
There are countless varieties of tomatoes out there. This is especially true if you’re a gardener or homesteader growing heirloom varieties.
(By the way, I HIGHLY recommend that you try growing tomatoes at home if you haven’t yet. There are SO MANY cool varieties you can grow at home that you’ll never find in stores! Read more about how to grow tomatoes from seed right here, and check out some of the incredible varieties of tomatoes you can grow at home here – affiliate link).
The best tomatoes for canning, however, are paste tomatoes (also known as plum tomatoes). This is because paste tomatoes are meatier with less liquid and less seeds than slicing tomatoes. While they’re not great for fresh eating, they’re excellent for canning and making tomato sauce because there’s less liquid to cook off and less seeds to either filter out or that will get blended in with the sauce.
Here on Vancouver Island, we grow San Marzanos as well as a dual purpose variety called Ardwyna Paste tomatoes. The Ardwynas are a local heirloom variety and are hardtop come by, but if you do happen upon some meds one day, I highly recommend then as they work great as both a paste tomato and a slicer!
Either way, choose a paste variety of tomato for canning purposes.
How (and why) to freeze tomatoes before canning
If you grow your own food, you know that everything seems to come on at once and, seemingly overnight, you find yourself elbows deep in produce that needs to be preserved before it goes bad.
In some cases, this means you need to break out your canner right away and start processing your fruits and veggies while they’re at their peak. Vegetables like cucumbers need to be processed fresh and turned into pickles right away before they go soft. The same is true for fruits like peaches.
But in the case of tomatoes, not only can you toss them in the freezer first before you’re ready to can them, it’s actually easier to peel them if you freeze them first.
This works great for us because while I’m busy canning everything else, I can just toss my tomatoes in the freezer and worry about canning them later in the year when I have more time.
In fact, I’ve been known to do a lot of my tomato sauce canning in January when I finally get around to pulling the bags out of the freezer!
But even if you only freeze them for a day or two, they’ll be much easier to peel and prepare for canning if they’re frozen first.
To freeze tomatoes, first wash them and remove the cores. Then toss them in a freezer bag and freeze until frozen solid.
How to peel tomatoes
If you’ve frozen your tomatoes first, peeling is a cinch. Simply run frozen tomatoes under hot water and slip the skins right off!
If you decide to peel them fresh, there are a couple ways you can go about this…
Option 1: Blanch tomatoes in boiling water for about 30 seconds, then plunge them into an ice water bath until the skins begin to slip off. Once you see the skins begin to peel off, remove tomatoes from the ice water and peel the rest of the skins off with your hands.
Option 2: Use a food mill to remove the skins. If you have a food mill, this is an easy way to removes the skins and turn your tomatoes into sauce at the same time! However if you want to keep any of the tomatoes whole for any reason, you’ll want to peel them by hand.
How to make homemade tomato sauce
Once your tomatoes are cored and peeled, the hardest part of your work is already done!
From here, all you need to do is toss them in a large stockpot and start cooking them down.
If your tomatoes are frozen, you’ll need to cook them for a little bit longer until they begin to warm up and cook down. However if they’re frozen, what I like to do is leave them in the pot with the lid on for a couple hours before cooking and a lot of water will naturally drain out as they begin to thaw. I then pour that excess water out before I begin to cook them down. This makes for a thicker sauce in less time.
If you’re starting with frozen tomatoes, heat them over medium heat –stirring frequently to prevent scorching– until they’re completely thawed and begin to soften.
Once tomatoes are thawed (or if using fresh tomatoes), bring them to a boil over medium-high heat. Use a potato masher to help crush the tomatoes down. Continue cooking, stirring and crushing tomatoes until all of the tomatoes are soft and have released their juices (about 10 to 15 minutes).
Using an immersion blender, blend the tomatoes until smooth. Alternatively, transfer in batches to a blender or food processor and blend before returning sauce to the pot.
Bring sauce to a boil over high heat, stirring frequently. Reduce heat to medium-high and boil until volume is reduced by about half. (You may want to use a splatter guard to keep the sauce from splattering all over your kitchen as it cooks down!)
How to can homemade tomato sauce
To can your tomato sauce, start by preparing your canner and jars. This process will be slightly different depending on whether you decide to water bath can your sauce or pressure can it. (See specifics below).
Once your jars and canner are ready, fill each jar with bottled lemon juice and salt (if using).
For pint jars, fill each pint jar with 1 tablespoon bottled of lemon juice and ½ teaspoon of salt.
For quart jars, fill each quart jar with 2 tablespoons of bottled lemon juice and 1 teaspoon of salt.
(The salt is optional, however the lemon juice is not. You MUST use bottled lemon juice for this recipe to ensure the acidity and safety of your home-canned tomato sauce).
Personally, I don’t even notice the taste of the lemon juice in the sauce, but some people prefer to use citric acid to avoid any flavour the lemon juice might impart. If you choose to use citric acid instead of lemon juice, add ¼ teaspoon of citric acid per pint jar or ½ teaspoon citric acid per quart jar.
If you’d like to add any herbs, you can add some now. Dried basil, oregano and thyme are all good options for tomato sauce. You can use just one herb or a combination of dried herbs if you like. Add ½ teaspoon dried herbs to each pint jar or 1 teaspoon dried herbs to each quart jar.
How to water bath can tomato sauce
To water bath can tomato sauce, ladle hot tomato sauce into prepared jars, leaving ½ inch headspace. (Make sure you’ve added your lemon juice first -and salt, if using).
* If you’re new to canning, follow the steps for water bath canning here.
Remove air bubbles and adjust headspace as needed. Wipe rims, place lids on top and screw down bands.
Place jars in canner and bring water to a boil. Process pint jars for 35 minutes and quart jars for 40 minutes.
After time is up, turn heat off, take the lid off the canner and allow jars to sit in hot water for another 5 minutes. Remove jars and let cool completely before storing.
How to pressure can tomato sauce
To pressure can tomato sauce, ladle hot tomato sauce into prepared jars leaving 1 inch headspace. (Make sure you’ve added your lemon juice first -and salt, if using).
* Again, if you’re new to canning, follow the step-by-step for pressure canning instructions here.
Remove air bubbles and adjust headspace as needed. Wipe rims, place lids on top and screw down bands.
Place jars in pressure canner and process both pint and quart jars for 15 minutes at 10 lbs. of pressure. (Increase to 15 pounds of pressure if canning at over 1,000 feet above sea level).
Once processing time is finished, turn off the heat and allow the pressure canner to depressurize completely, then remove weighted gauge and wait another 2 minutes. Remove lid and wait another 10 minutes before removing jars from canner. Remove jars and let cool completely before storing.
How many tomatoes do I need to can tomato sauce?
This recipe for home-canned tomato sauce is very flexible, so you can use as many tomatoes as you have.
However on average, you’ll need about 7 pounds of tomatoes for every two pints (one quart) of sauce.
A note about siphoning
If you pull your jars of tomato sauce out of the canner and notice that a bunch of the sauce appears to be missing, you may be the victim of siphoning.
Siphoning is when sauce or liquid is drawn out of canning jars while in the canner. It happens when there’s a quick and drastic change in temperature.
Siphoning is much more common in pressure canning than water bath canning (which is why I tend to prefer to water bath can my tomato sauce).
The best way to prevent siphoning and liquid loss is to make sure that your jars and sauce are hot when they go into the canner, and make sure to leave your jars to sit in the canner for the recommended time after your processing time is up. This reduces the chance and amount of siphoning over all, however some liquid loss may still occur when pressure canning.
This being said, some siphoning is normal when pressure canning, and as long as the lids have sealed and the jars haven’t lost more than half the amount of liquid in them, your tomato sauce will still be safe to store and eat.
How to use your home-canned tomato sauce
There are so many ways to use home-canned tomato sauce. Use it as a base for pizza or as a sauce to top some homemade pasta. Use it in soups and stews and as a base for all kinds of red sauces and casseroles.
The sky’s the limit!
I’ve definitely got my favourites, but I’d love to know, what are your favourite ways to use tomato sauce at home?
Let me know in the comments below:)
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