When canning fresh tomatoes, blanch and core them, and season them before and during canning. To blanch tomatoes, put them briefly in boiling water, then put them in ice water to make the skins easy to remove. Core them before or after this step to remove tough tissue.
Add some seasonings, such as garlic or basil, during the cooking and canning process for more flavorful tomatoes, or leave them unseasoned for an unchanged taste. An acid, such as lemon or lime juice, helps preserve the tomatoes during storage. A pressure cooker or canning machine makes canning easier, less labor-intensive, and safer for beginners.