Tomatoes are botanically classifies as fruit. You will find tomato recipes for juices, sauces, pickles, relishes and even preserves. The amount of natural acid in tomatoes varies depending on the variety, growing conditions, maturity and handling.
To ensure adequate amounts of acid are present when canning recipes using tomatoes, bottled lemon juice (not fresh) or vinegar labeled 5 present acidity is added to acidify the recipe. By maintaining the correct pH level, tomatoes can be processed safely in a water bath canner (boiling-water canner or hot water canner).