Here we work through the USDA procedure for home canning plain crushed tomato.
The crushed tomato meant here is pure, unadulterated crushed tomato, with no other fresh or dried vegetable of any other kind added to it. It would be unsafe to do so with this procedure below.
All home-canned crushed tomatoes must be acidified or they are not safe for consumption.
Jars must also be processed: you have your choice of water-bath processing, steam canner processing, or pressure-canning. All these methods are lab-tested equivalents and no one of them is safer than the other.
Quantities of fresh tomatoes needed
Numbers are approximate guidelines. Results will vary by variety of tomato used, etc.
On average, as a very, very rough guideline, for fresh tomatoes expect to need about 1 kg per 1 litre jar (2 1/4 to 2 3/4 lbs per US quart jar) of crushed tomato.
- 10 kg (22 lb) of tomatoes = 7 litres (US quarts) crushed tomato
- 6 kg (14 lbs ) of tomatoes = 9 x 1/2 litres (US pints) crushed tomato
- 1 US bushel tomatoes = 24 kg (53 lbs) = 17 to 20 litres (US quarts) crushed tomato
Jar size choices: Either half-litre (1 US pint) OR 1 litre (1 US quart)
Processing method: Water bath or steam canning or pressure canning
Headspace: 2 cm (1/2 inch)
Processing time: For water bath or steam canning the times are as follows. Half-litres (pints) 35 minutes; litres (quarts) 45 minutes
- Bottled lemon juice OR citric acid (mandatory)
- Salt OR non-bitter, non-clouding salt sub (optional)
- Wash tomatoes in fresh, potable water. Remove stems and hull the top bits out, trim out any bruised parts.
- Peel the tomatoes: Boil the tomatoes for 1 to 3 to 5 minutes (depending on the tomatoes) in hot water, then plunge them into a pan, sink or large bowl of very cold water. The skins will pull off easily. ( Yes, they must be peeled, to reduce the bacterial load. )
- Take 6 of the tomatoes, cut into quarters and add to a large pot over high heat.
- Crush them with a potato masher or other similar tool.
- After a few minutes of heating, the tomatoes will soften and release some juice.
- Stir the pot frequently and keep the heat high. Quarter a few more tomatoes, and add them and crush them right away. When the pot returns to a boil, then gradually repeat the process with the remaining tomatoes, each time waiting till the pot returns to a boil so that newly sliced tomatoes will be hit with full heat right away upon slicing and adding.
- No need to crush the tomatoes further, they will break down on their own.
- When all the tomato is in, let simmer uncovered for another 5 minutes. Stir to prevent scorching.
- MANDATORY. Acidify jars. To each half-litre/ pint jar add either 1 tablespoon bottled lemon juice OR ¼ teaspoon citric acid. To each litre/quart jar add either 2 tablespoons bottled lemon juice OR ½ teaspoon citric acid.
- OPTIONAL: ½ teaspoon salt per half-litre/ pint; 1 teaspoon per litre/quart jar.
- Ladle hot crushed tomato into jars.
- Leave 2 cm (1/2 inch) headspace.
- Wipe jar rims.
- Put lids on.
- Process in a water bath or steam canner.
- Process half-litres (pints) for 35 minutes; litre (quart) jars for 45 minutes. Increase time as needed for your altitude.
Boiling water bath or steam canning
Crushed tomato mixture is to go into jars piping hot. Steam-canning cannot be used as an option if the processing time at your altitude would be over 45 minutes, owing to concern that some steam canner models would simply run out of water.
|Jar size||0 to 300 m (0 - 1000 feet)||300 to 915 m (1,001 - 3,000 ft)||916 - 1,830 m (3,001 - 6,000 ft)||1,831 m (6,000 ft) and above|
|1/2 litre (1 US pint)||35 mins||40 mins||45 mins||50 mins|
|1 litre (1 US quart)||45 mins||50 mins||55 mins||60 mins|
Pressure canning process
The USDA also offers a pressure canning process.
Note: The Ball / Bernardin Complete book replicates the USDA pressure canning directions, but suggests increasing the headspace for pressure canning to 3 cm (1 inch).1
Crushed tomato mixture is to go into jars piping hot. Guidelines below are for weighted-gauge. See also if desired: Dial-gauge times.
|Jar size||Time||0 to 300 m (0 - 1000 feet) pressure||Above 300 m (1000 ft) pressure|
|1/4 litre, 1/2 litre or 1 litre (1/2 US pint, 1 US pint or 1 US quart)||15 mins||10 lbs||15 lb|
|1/4 litre, 1/2 litre or 1 litre (1/2 US pint, 1 US pint or 1 US quart)||10 mins||15 lbs||not recommended|
How and why to peel tomatoes.
More information about canning tomatoes in general.
How to water bath process.
How to steam can.
When water-bath canning or steam canning, you must adjust the pressure for your altitude.
How to pressure can.
When pressure canning, you must adjust the pressure for your altitude.
Keeping the crushed tomato plain like this, without even any salt, is actually a great advantage, because it gives it maximum versatility when you go to use it for soups, stews, casseroles, chiles, etc.
You may, however, should you choose, safely add seasoning in the form of dried herbs. In fact, if you wanted to give your crushed tomato a Latin American spin, you could use bottled lime juice in place of bottled lemon juice (keeping the amounts the same.)
The reason you want to cut and heat as you go, bit by bit, is to quickly neutralize with heat an enzyme that is released by slicing which will otherwise cause solids and liquid separation in the jars. It’s not an out-dated procedure, it’s actually a brilliantly simple answer to an age-old problem. For more information, see tomatoes separating.
If you did make the crushed tomato a day ahead right up to the canning stage, but then called it a day and stored it in the fridge, then bring it back to the boil in a pot before starting the canning procedure.
Crushed tomatoes. United States Department of Agriculture (USDA). Complete guide to home canning. Agriculture information bulletin No. 539. 2015. Page 3-7.
General information on canning tomatoes.
Acidification of tomato products: United States Department of Agriculture (USDA). Complete guide to home canning. Agriculture information bulletin No. 539. 2015. Page 3-5.
Kingry, Judi and Lauren Devine. Ball / Bernardin Complete Book of Home Preserving. Toronto: Robert Rose. 2015. Page 376. ↩