Foods that contain enough acid to have a pH of 4.6 or lower. Fruits, fruit juices, jams, jellies, marmalades, fruit butters and most tomatoes are naturally high-acid foods. Pickles, sauerkrauts, relishes, chutneys and salsas that include vinegar or citric acid as an ingredient are also considered high-acid foods.
According to current USDA guidelines, high-acid foods may be processed safely in a water-bath canner.
Note: Tomatoes with orange or yellow skins must have an acid added to them to be considered a high-acid food.