This is the 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.
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.
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.
- 1 Quantities of fresh tomatoes needed
- 2 Prepare the tomatoes
- 3 Cook the tomatoes
- 4 Prepare the jars
- 5 Fill the jars
- 6 Headspace
- 7 Finishing the jars
- 8 Processing
- 9 Reference information
- 10 Crushed tomatoes separating in jars
- 11 Source
- 12 Further Reading
Quantities of fresh tomatoes needed
Numbers are approximate guidelines. Results will vary by variety of tomato used, etc.
On average, as a very rough guideline, expect to need about 1 kg (2 1/4 to 2 3/4 lbs) of tomatoes per 1 litre (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
Prepare the tomatoes
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. )
Cook the tomatoes
Quarter the tomatoes.
In a large pot over high heat, heat one-sixth of the tomato quarters quickly.
As they heat, use a very sturdy spoon or a potato masher or a wooden mallet to crush them.
The reason you want to heat these quickly is to quickly neutralize an enzyme which will otherwise cause solids and liquid separation in the jars.
Stir continually to prevent burning.
The tomatoes will release juice.
Gradually add the remaining quartered tomatoes, gradually enough so that you don’t lose your boil. No need to crush these, they will break down on their own.
When they are all in, boil for an additional 5 minutes.
Prepare the jars
You can use half-litre (1 US pint) or 1 litre (1 US quart jars.)
Wash the jars in hot water.
Add to each jar:
- half-litre (pint): one tablespoon bottled lemon juice or 1/4 teaspoon citric acid
- litre (quart): two tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid
Fill the jars
Fill the jars with the hot crushed tomato mixture. Note that the guidelines expect the sauce to be boiling hot inside the jars when the jars go into the canner. It’s okay if the crushed tomato has gone off the boil for a few minutes; what’s not okay is crushed tomatoes made yesterday cold from the fridge.
If you did make the crushed tomato a day ahead then bring it back to the boil in a pot before starting the canning procedure.
There isn’t agreement over how much headspace is best, so you will need to see what you have the best luck with over time:
- 2 cm (1/2 inch) headspace is called for by the USDA.1
- 3 cm (1 inch ) is called for by Ball / Bernardin2
The headspace recommendations apply to whatever jar size used.
Finishing the jars
Wipe rims, put on lids, put canning rings on finger-tip tight. Place in canner.
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.
|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)||40 mins||45 mins||50 mins||55 mins|
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 to pressure can.
When pressure canning, you must adjust the pressure for your altitude.
How to water bath process.
How to steam can.
When water-bath canning or steam canning, you must adjust the pressure for your altitude.
More information about canning tomatoes in general.
Crushed tomatoes separating in jars
Occasionally, you may can a variety of tomato that separates in the jar into tomato solids and liquid, as in the photo above.
It’s not overly-photogenic and looks like a canning fail.
Yet, it’s perfectly safe.
Bernardin explains why this can happen and how to reduce the chance of its occurring:
During storage, pulp and juice in home canned tomatoes may separate, especially in sauce or juice made with crushed or puréed tomatoes. Separation is caused by an enzyme, Pectose (Pectinesterarse), found in high concentrations in tomatoes. The enzyme is activated when tomatoes are cut. To reduce separation, heat tomatoes quickly over high heat to 82 C (180 F) to destroy the enzyme.”3
If you’ve ever wondered at a reason behind the USDA’s otherwise-mysterious way of doing crushed tomatoes, not actually crushing them but rather heating tomato quarters a bit at a time (as opposed to just whipping them all in a food processor), that enzyme is likely the reason. Their preparation method would allow heating to occur relatively rapidly to kill the enzyme off before it got a chance to act:
Heat one-sixth of the quarters quickly in a large pot, crushing them with a wooden mallet or spoon as they are added to the pot. This will exude juice. Continue heating the tomatoes, stirring to prevent burning. Once the tomatoes are boiling, gradually add remaining quartered tomatoes, stirring constantly. These remaining tomatoes do not need to be crushed. They will soften with heating and stirring. ”4
When it does happen, you can turn it into an advantage. If you are going to be using the crushed tomato in a recipe that would have you boil it down, if you are careful when you go to remove the tomato from the jar, you can leave that water behind and save yourself a lot of boiling-down time. (If it’s a recipe that might be counting on that added liquid, such as, say, a chili or a soup, then you probably want to tip the whole jar in.)
Note that some people feel this is particularly prone to happening when slicing tomatoes, as opposed to paste tomatoes, are used.
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.
United States Department of Agriculture (USDA). Complete guide to home canning. Agriculture information bulletin No. 539. 2015. Page 3-7 ↩
Kingry, Judi and Lauren Devine. Ball / Bernardin Complete Book of Home Preserving. Toronto: Robert Rose. 2015. Page 376. ↩
Bernardin Guide to Home Preserving. Toronto, Canada: Bernardin Ltd. 2013. Page 48. ↩
United States Department of Agriculture (USDA). Complete guide to home canning. Agriculture information bulletin No. 539. 2015. Page 307. ↩