1. Tomatoes Tart and Tasty!
Welcome to our series of Wisline programs on home food preservation. Today we will talk about the basics of canning tomatoes safely. Tomatoes are without a doubt the most widely home-canned product in the U.S. However, to avoid spoilage and the risk of food poisoning, home canning must be done properly. Today we will talk about safely canning tomatoes…tart and tasty.
Before we get started, let’s see who is joining us today. (Roll call)
Thanks to everyone for joining us today. Let’s get started.

2. Resources for Today Tomatoes Tart and Tasty (B2605)
Using and Caring for a Pressure Canner (B2593)
Many of the points in today’s discussion come from our UWEX publication:
B2605 Tomatoes Tart and Tasty!
And, for pressure canning tomatoes, another good resource is B2593 Using and Caring for a Pressure Canner.
Both of these resources are available online:

3. Tomato Acidity Varies Type of tomato
Conditions during the growing season
Soil in which the plants are grown
Tomatoes require a certain level of acid for safe home canning (pH of 4.6 or less – or the production of botulism toxin becomes an issue). The acid level of tomatoes varies due to several factors including the:
type of tomato (varieties vary some in acid level)
conditions during the growing season
soil in which the plants are grown.
This variation often places tomatoes close to the cut-off for safe canning.

4. Other Factors that Affect Tomato Acidity
Tomato juices are less acidic than tomato solids
Over-ripe tomatoes will decrease overall acidity
Adding low-acid ingredients will decrease acidity
Canning itself can decrease acidity
In addition to the raw tomato fruit, several other factors influence the safety and acidity of canned tomato products:
Tomato juices are less acidic than tomato solids
One or more over-ripe tomatoes in a jar will decrease the overall acidity
Adding low-acid ingredients- onions, celery, garlic, peppers- will decrease the acidity
Canning itself can decrease acidity
Small-fruited cultivars and white, yellow and pink tomatoes are in the same acidity range as most standard red tomatoes. The difference in taste of these ‘low acid’ tomatoes is due to higher sugar content which masks acid flavor. Paste tomatoes are, however, consistently LOWER IN ACID (higher in pH) than standard tomatoes So add acid, regardless of color.

5. All Tomatoes are not Created Equal..
Don’t can over-ripe, damaged or decayed tomatoes
Don’t can tomatoes exposed to frost or harvested from frost-killed vines
Don’t can late season tomatoes ripened indoors
Some tomatoes are not ‘created equal’ and should not be used for canned tomatoes or juice. Tomatoes not suitable for canning may be trimmed and eaten fresh, or heated and used in a frozen product.

6. How much acid do I add? Citric Acid Little change in flavor
½ teaspoon per quart
Bottled Lemon Juice
Easy to use
2 Tablespoons per quart
Vinegar (5% acidity)
Noticeable change in flavor
4 Tablespoons per quart
Citric acid – increases acidity with little change in flavor; use 1/2-teaspoon citric acid per quart or 1/4-teaspoon per pint.
Bottled lemon juice – easily obtained (don’t use fresh). Add 1 tablespoon per pint or 2 tablespoons per quart; add a small amount of sugar if desired. Vinegar can not substitute for lemon juice unless directed in the recipe. Be sure to add acid to all canned tomato products, whether pressure canned or water-bath canned.
If any of your tomato recipes pre-date 1994, be sure to update your files!! Research results released in 1994 indicated significant changes in canning; and canning of tomato products was particularly affected.

7. Question time??
Let me take a minute to ask is there are any questions that you have at this point.
Why can’t I simply pressure can my tomatoes, without adding acid?

8. Many Options for Preserving Tomatoes:
Pressure Canning
Water Bath Canning
Freezing
Drying
There are many options for successfully preserving tomatoes:
Many tested recipes offer the option to either pressure can or water bath can tomatoes. Be sure to follow directions completely. Don’t simply substitute pressure canning for water bath canning, and vice versa. An unsafe product may result.
There are several options for freezing tomatoes in our ‘freezing fruits and vegetables publication’
Freezing tomato juice
Freezing tomato puree (no heating step, so use within 2 months)
Freezing crushed, stewed tomatoes
Freezing raw tomatoes
And drying tomatoes using an oven or home dehydrator. Drizzle with salt and olive oil- delicious!

9. A Friendly Reminder…..
Unsafe methods for canning include: open-kettle, microwave, or oven canning
Don’t thicken tomato products before canning
Tomatoes mixed with vegetables must be pressure canned
Beware of unsafe canning methods.
And don’t thicken products before canning. Tomato products can be thickened after canning- during preparation- or choose freezing as a way of preserving thickened products.
Tomatoes that are mixed with celery, onions, peppers or other low-acid products must be processed in a pressure canner.

10. Watch those Recipes! Tomatoes in Water Tomatoes in Juice
Sort and wash tomatoes. Remove skins. Raw pack into clean, hot canning jars, leaving ½-inch head space. Add acid and hot water. Process. Quarts -
Boiling water – 50 min
Dial gauge–10 min (11 psi)
Weighted gauge–10 min (15 psi)
Tomatoes in Juice
Sort and wash tomatoes. Skin. Pack tomatoes into clean, hot canning jars. Cover with hot tomato juice, leaving ½-inch headspace. Add acid. Process. Quarts –
Boiling water – 90 min
Dial gauge-25 min (11 psi)
Weighted gauge-25 min (15 psi)
Small changes in a recipe can make a big difference. Here, the processing times are the same for hot and raw pack, and there are many options for the type of process: water bath canning vs pressure canning. The big difference in processing results from the type of liquid used in packing- water (cooking liquid) or juice. Tomato juice transfers heat less effectively than water, so using juice to pack whole or half tomatoes will dramatically increase the processing time.

11. Hints for a Safe, High Quality Product
Process using the hot-pack method
Process tomatoes separately from low-acid ingredients
Add meat only where directed
Don’t thicken tomato products before processing
The enzymes in tomatoes, especially pectin methylesterase, tend to be rather heat stable. This enzyme causes breakdown in cell wall structure, which is good when tomatoes are ripening but disheartening when it means that your tomato juice separates in the jar. Hot packing tomatoes so that the fruit heats quickly will usually help preserve quality.
Adding onions, peppers, garlic and other low-acid ingredients will dramatically increase the processing time. Consider preserving peppers and onions separately (perhaps by freezing or drying) and adding them to the tomatoes as you prepare them for the table.
Don’t add meat to ‘meatless’ spaghetti sauce!
Don’t thicken tomato products before processing.
And what about tomato jam….. Etc.

12. Question time??
Let me take a minute to ask is there are any questions that you have at this point.

13. Next Time:
Homemade Pickles and Relishes (B2267)