摘要:Tomatoes are a popular vegetable for home canning. USDA Guidelines recommend lemon juice or citric acid be added to home-canned tomatoes to increase acidity. In 2007 and 2008, we grew and tested the pH of 15 tomato varieties. Three of the heirloom varieties had statistically lower acidity than the hybrid used as a standard for comparison. Canning tomatoes generally involves using different tomato varieties at various stages of ripening. Although some control of acidity can be exercised by variety selection, Extension agents should encourage those involved in home canning to follow USDA guidelines regardless of the tomato varieties used.