Canning Tomatoes Safely

Tomatoes are the most widely home-canned product in the United States. Many factors affect the acidity of canned tomatoes i.e. growing low acid tomatoes, overripe produce, damaged or decayed produce, and tomato juices are less acidic than tomato solids.

Since so many factors affect the acidity of canned tomatoes, the United States Department of Agriculture (USDA) recommends that acid be added to home canned tomato products. Bottled lemon juice can be used to acidify canned tomato products. Add one tablespoon of lemon juice per pint and two tablespoons per quart. Measure this amount into canning jars before sealing.

Small amounts of vinegar are not as effective as lemon juice in increasing acidity. Enough vinegar to increase the acidity of canned tomatoes changes the flavor of the canned product. For this reason, vinegar is not recommended.