Why is it necessary to add bottled lemon juice or citric acid to some home canned tomato recipes? Must the lemon juice be bottled lemon juice?
Tomatoes have a pH (acid) level that is just above the line dividing high-acid foods and low-acid foods. It is important for the safety and quality of tomato recipes that the proper acid level is maintained. Since many factors can decrease the natural acidity in tomatoes, the addition of bottled lemon juice or citric acid helps ensure the correct acidification. Bottled lemon juice must be used because its acid level is consistent, unlike fresh lemons.