Are there special concerns in canning tomatoes?
Yes, tomato varieties vary in acidity. Growing conditions, climate and locations also affect the acidity level. Overripe and infected tomatoes may be low enough in acid to support Clostridium botulinum. Use only firm, ripe tomatoes that have no spoiled parts or mold. Tomatoes harvested from dead vines are low in acid. They can be eaten fresh or frozen, but do not can tomatoes from dead vines.
