Whether you are experienced at home canning or a beginner, you must know how to safely preserve your harvest of tomatoes. Unsafe canning methods can create not only spoiled tomatoes, but also the odorless, tasteless, deadly poison of botulism. Clostridium botulinum thrives in conditions with low acidity and a lack of oxygen; conditions inside an improperly canned jar of tomatoes.
Tomatoes require additional acidification before canning. Commercially bottled lemon juice should be added to each jar; 1 tablespoon per pint, 2 tablespoons per quart. Citric acid can also be used: teaspoon per pint or teaspoon per quart. The acidity of fresh tomatoes has declined measurably over the years. It is related to the varieties of tomatoes being grown and to growing conditions. To be safe, add the required lemon juice or citric acid. Sugar can be added to offset the acid test, if desired.
Overripe tomatoes are lower in acid and should not be canned. Also, tomatoes from dead or frost-killed vines have an unpredictable acidity and should not be canned. Choose to freeze these tomatoes or the sauces made from them.
Use reliable recipes for canning tomato products; recipes tested and USDA approved after 1994. Reliable recipes and excellent canning instructions can be found online at the National Center for Home Food Preservation: nchfp.uga.edu. When making a sauce, salsa or recipe that adds onions and other vegetables to tomatoes, the acid of the tomatoes will be diluted to unsafe levels. You must follow approved recipes or use a pressure canner.
The revised standards for safely canning tomatoes in a water bath also extended the time needed for processing. Whole or halved tomatoes, without added liquid or packed in juice (either hot or raw pack) must be processed for 85 minutes; both pint and quart jars. (Plus add 5 minutes for our local altitude, above 1,000 feet). Other tomato products, such as hot pack juice may be safely canned for less time. Please check for specific processing times at the above website.
Volunteers and some staff members at Cornell Cooperative Extension completed the intensive training to become certified as Master Food Preservers. If you have specific questions, please call: 664-9502, ext. 217
The mission of the Chautauqua County Master Gardener Program is to educate and serve the community, utilizing university and research-based horticultural information. Volunteers are from the community who have successfully completed 50-plus hours of Cornell approved training and volunteer a minimum of 50 hours per year.
For more information on the Master Gardener Program, contact: Betsy Burgeson, Master Gardener coordinator, at 664-9502, ext. 204, or email Emh92@cornell.edu "Like" the Chautauqua County Master Gardeners on Facebook for gardening news and information.