Cooks love to experiment with salsa recipes and many want to preserve their winning combination by canning. Most salsa recipes are a mixture of low-acid foods (such as onions and peppers), with high-acid foods (such as tomatoes).
The type and amount of ingredients as well as the preparation method are important considerations to safely preserve homemade salsa. Improperly home-canned salsas or other tomato-pepper combinations have been implicated in botulism poisonings. A USDA-tested recipe using the type and amount listed for each ingredient can ensure a safe, home-canned salsa.
Changing the type or amount of ingredients alters the acidity of the product, making it unsafe. If you have a personal favorite that is not a tested recipe, it is best to eat your creation fresh, store it up to one week in the refrigerator (40°F or below), or freeze it. Most salsas should retain good quality for up to one year in a freezer maintained at 0°F.
Acidity – Acid ingredients help preserve canned salsas and make them safe to store on the shelf. The acids are usually commercially bottled vinegar (at least 5% acidity) or lemon juice. The amount of vinegar or lemon juice in a recipe for canning cannot be reduced.
Tomatoes – Paste tomatoes, such as Roma, have more flesh or solid tissue, producing thicker salsas. Select only disease-free, preferably vine-ripened, firm tomatoes. Do not can tomatoes from dead or frost-killed vines.
Peppers – Use only high quality peppers, choosing your favorite such as sweet bell, jalapeno, habanero, etc. Do not exceed the total amount (pounds or cups) of peppers in any recipe.
Spices and Herbs – Amounts of spices and herbs in these recipes (black pepper, salt, oregano, pickling spice, dried red pepper flakes, and ground cumin) may be altered.
Other – Red and yellow onions may be substituted for each other. Do not exceed the total amount of onions in any recipe.