Home canner’s column: A taste for tomatoes
by KAYE M. SMITH Extension Agent Family & Consumer Sciences
Jul 10, 2011 | 2109 views | 0 0 comments | 9 9 recommendations | email to a friend | print
Do you enjoy the fresh taste of tomatoes just off the vine and still warm from the sun? Nothing reminds us more of summer than homegrown tomatoes. This is the vegetable we long for most when supermarkets offer less flavorful tomatoes grown in greenhouses.

If processing tomatoes with citric acid or lemon juiced added is not part of your tomato canning procedures, you need to update your canning information. Tomato processing procedures have changed over the past few years.

Tomatoes are considered a high acid food but the amount of acidity can vary according to type. The latest recommendations from USDA include adding acid and processing some packs of tomatoes 85 minutes in a boiling water bath. If you are using a pressure canner, call us for the preparation procedures and processing times.

Also, remember to process your tomatoes and other foods at a pressure and time appropriate for your altitude. If you live in altitude greater than 1,000 feet above sea level, you need to make adjustments. Call your local Extension office to find out if and how you need to make these adjustments.

Other recommendations for home canning from USDA include:

— Sterilizing jars in boiling water for 10 minutes if not processing foods for 10 minutes or more.

— Pre-treating lids according to manufacturer’s recommendations. Lids are often simmered before using. However, some lids require different pre-treatments.

— Processing high acid foods (jellies, fruit and pickles) in a water-bath canner according to tested recipes. This kills molds and other spoilage organisms that can grow during storage. Using paraffin for jellies is no longer recommended.

— Processing low acid foods (vegetables, meats and seafood) in a pressure canner according to tested recipes. This kills spoilage organisms and bacteria that cause botulism.

— Venting all pressure canners 10 minutes before the weight is put on the vent pipe or the petcock is closed. Venting means allowing steam to escape from your canner through the vent pipe. This is important for driving air out of the canner so that you can reach the 240 degrees needed to kill harmful bacteria.

— Removing air from the jars before applying lids. Use a rubber spatula or a plastic “debubbler” available where canning supplies are sold. A metal knife or spoon may weaken jars so they crack during processing. Removing air helps ensure that your food is processed at temperatures high enough to kill harmful bacteria.

— Reprocessing jars that do not seal within 24 hours. Always use new lids and re-process for the full amount of time recommended in the recipe. The quality of the food will be lower, but it will be safe. Alternatives to reprocessing are to refrigerate the food and use in one or two days, or freeze it.


Q. Do you know of an easy way to peel tomatoes for canning?

A. The best way to peel tomatoes is to dip them in boiling water for 30 to 60 seconds then dip them in cold water to split the skins. The skin should slip off. Hint: If you cut a small “x” on the bottom before dipping, it helps them split more easily.

Q. I understand why tomatoes need to be acidified with bottled lemon juice but I’m not sure how much to use.

A. To ensure safe acidity in whole crushed or juiced tomatoes, add two tablespoons of bottled lemon juice or ? teaspoon of citric acid per quart of tomatoes. For pints, use one tablespoon bottled lemon juice or 1/4 teaspoon citric acid. Add the acid to each jar rather than adding to the entire batch of tomatoes.

Q. I like to add celery, green pepper, and onions to tomatoes when I can them. Is this safe?

A. Adding other vegetables lowers the acidity of tomatoes, which can provide a favorable environment for the growth of bacteria that cause botulism. This product would require the pressure canner method of processing and use of tested recipes.

If you have food preservation questions you would like addressed in the “Home Canner’s Column,” call your local office of University of Tennessee Extension-Bradley County at 728-7001. The Bradley County Cannery is opened by appointment by calling the facility at 728-7031. It is open Tuesday through Friday. We look forward to your questions.