How to Can Chopped, Crushed or Diced Tomatoes Safely

Garden fresh tomatoes – the crown jewels of the garden.  No other tomatoes come close to the fresh, flavorful taste of garden tomatoes.
garden roma tomatoes in basket

We start the season picking one or two tomatoes for sandwiches – mmm, toasted tomato sandwiches!  Soon we’re picking bowls of tomatoes for fresh salsa and bruschetta – oh so good. By mid-September, there are no bowls big enough to hold all the tomatoes, time to haul out the boxes and start freezing, canning and dehydrating!

boxes of tomatoes
Canning tomatoes is not difficult, but it does take time.  And yes, there are some important safety guidelines (more details below) you need to follow – but even those are super easy. Basically, you just need to add acid (lemon juice or vinegar) and water bath your cans for a specified amount of time.  No big deal.
canning tomatoes with acid
Here are the simple steps I use for canning tomatoes.   I like chopped or diced canned tomatoes, but you can leave your tomatoes any size you prefer.  I’ve provided two options, one with the skins on and one including how to peel the tomatoes.

Do I have to Peel Tomatoes for Canning?

Updated, 2020 – I’ve always said peeling was optional. But the USDA Complete Guide to Home Canning says that peeling root crops and tomatoes greatly reduces the number of bacteria, yeast and molds. So they recommend peeling tomatoes.

The National Center for Home Food Preservation includes instructions for peeling tomatoes in most of their canned tomato products – (not their tomato juice recipe). They also say their canning instructions are meant to be followed as written and changing ingredients or steps may impact quality and safety of the final product. Another vote for peeling tomatoes.

Now, you would think that the amount of time tomatoes are boiled before canning and once again during the canning process would be enough to eliminate dangerous pathogens – but the safe thing to do is follow the experts’ advice and peel tomatoes.

 canned tomatoes

Canning Crushed Tomatoes – With Peeling

1. Wash tomatoes and remove any blemishes.
2. Peel tomatoes. Make a small X on the bottom of the tomato, place it in boiling water for 60 seconds then transfer immediately to an ice water bath and peel. The peel will slip right off.
peeled tomatoes
3. Chop tomatoes and toss into a large pot.
4. Bring chopped tomatoes to boil for 5 minutes.
5. Pack hot tomatoes into clean, hot jars (they need to be hot so the jars won’t crack, but they don’t need to be sterilized because our hot water bath will be more than 10 minutes).

6. Add lemon juice to each jar. VERY IMPORTANT for safe canning.   Add 2 tbsp lemon juice per 1 Litre or 1 Quart jar.  Add 1 tbsp to each 500 ml or 1 Pint jar.

7. Seal with hot sealing lid.
8.  Place in hot water bath.  Boil litre or quart jars for 45 minutes.  Boil 500 ml or pint jars for 35 minutes.
For more safe, tomato canning options check out the National Centre for Home Food Preservation.

Safety Issues around Canning Tomatoes and Tomato Products

Tomatoes are Borderline between High Acid and Low Acid

The issue with canning tomatoes is that the level of acid in tomatoes varies.  Some are high acid and some are low acid and even though the sticker at the greenhouse may say “high or low acid” tomato, there’s really no way for us home canners to know for sure.  Those labels are helpful, but they’re no guarantee and furthermore, growing conditions may also affect just how acidic or not those tomatoes end up being.  In other words, to be safe, we should add acid to our tomatoes.
Clostridium Botulinum
One of the most dangerous pathogens and one we want to avoid in home canning is Clostridium botulinum, the bacteria that causes botulism and it can be fatal. This bacteria thrives in high moisture, low acid, low salt and low oxygen environments.  Canned tomatoes, tomato products, meat, soups, stews, fish, beans and other low acid foods provide the ideal environment for botulism spores.
 
How to avoid Clostridium Botulinum in Home Canned Goods
– use high acid foods
– add acid (follow tested recipes to ensure the correct amount, see National Centre for Home Food Preservation)
– heat low acid veggies, meats and other canned goods in a pressure canner where temperatures can get to the required 240°F/116°C and process it for the recommended time.  Again, it’s important to follow the recommended times provided by tested recipes from a trusted source like the National Centre for Home Food Preservation
Canned tomatoes are a great addition to any pantry and by following current practices, you can rest easy knowing you’ve done your best to ensure a safe and delicious product.
Getty Stewart is an engaging speaker and writer providing tasty recipes, time-saving tips, and helpful kitchen ideas to make home cooking easy and enjoyable. She is a Professional Home Economist, author of Manitoba’s best-selling Prairie Fruit Cookbook, Founder of Fruit Share, mom and veggie gardener.

Similar Posts

7 Comments

  1. can I use frozen garden tomatoes just cut up and frozen not cooked first to a cooked salsa?

    1. There’s no safety reason why you can’t add them to cooked salsa, but flavor and texture will likely be different. You might need to cook the salsa a little longer to evaporate the liquid from the tomatoes or you could add a can of tomato paste to get a thicker texture. The peel will likely also come off the tomatoes and make little curled up bits in your salsa – not a big deal.
      Sometimes in the busy garden season when I can’t keep up with my tomatoes, I’ll toss fresh, raw tomatoes in the freezer. I typically use them in soups or stews where the extra liquid isn’t an issue. Sometimes, I’ll puree them before adding into a dish so that the tomato peel isn’t noticed by anyone.
      Hope this helps.

      Getty

Comments are closed.