Are tomatoes low acid or high acid (acidic)?
Tomatoes borderline acidic, and it depends on the variety. Some are more or less acidic than others. The USDA says: Although tomatoes usually are considered an acid food, some are now known to have pH values slightly above 4.6. Figs also have pH values slightly above 4.6. Therefore, if they are to be canned as acid foods, these products must be acidified to a pH of 4.6 or lower with lemon juice or citric acid. Properly acidified tomatoes and figs are acid foods and can be safely processed in a boiling-water canner. The University of Minnesota has a page dedicated to home canning tomatoes and says: Researchers at USDA and at the University of Minnesota have found that most underripe to ripe, cooked tomatoes have a pH below 4.6. Unfortunately, a few varieties may have a pH above or close to 4.6. These include • Ace, • Ace 55VF, • Beefmaster Hybrid, • Big Early Hybrid, • Big Girl, • Big Set, • Burpee VF Hybrid, • Cal Ace, • Delicious, • Fireball, • Garden State, • Royal Chico, • San Marza
