How to can tomato sauce safely

Start at the National Center for Home Food Preservation or the current USDA Complete Guide to Home Canning and select the exact tomato-sauce formula you intend to use. “Standard Tomato Sauce,” spaghetti sauce with meat, and spaghetti sauce without meat are different tested processes. Do not combine their ingredient lists or borrow a processing time from one for another. A family recipe, restaurant formula, or ordinary cooking recipe is not a canning process unless a recognized research authority tested that exact formulation.

Read the complete procedure before preparing food. Confirm the allowed tomato condition, permitted ingredients, jar sizes, headspace, acidification, canner type, processing schedule, gauge pressure where applicable, and elevation adjustment. Obtain the equipment needed for that procedure. A boiling-water canner and a pressure canner are not interchangeable merely because both heat jars.

Use sound, disease-free tomatoes and follow the tested preparation steps. NCHFP warns against tomatoes from dead or frost-killed vines for home canning. Do not add extra vegetables, meat, seafood, oil, flour, starch, fresh herbs, or other ingredients unless the selected tested recipe expressly includes them in the stated amount. Those changes can alter acidity, density, and heat movement through the jar.

This guide intentionally does not supply a hybrid ingredient list or a shortened processing table. Keep the tested source open while working and mark your elevation before beginning. Read the source’s notes as well as its table headings. Follow it exactly. If any required direction is unclear, pause and consult a local Cooperative Extension office rather than improvising.

Prepare jars, lids, tomatoes, and the canner exactly as the selected current procedure directs. Measure acidifying ingredients with proper measuring tools and use the specified type. Add them at the step and in the amount stated by the tested formula. Do not substitute fresh lemon juice for bottled lemon juice when the formula calls for bottled juice, and do not omit acid because the tomatoes taste tart.

Fill only the approved jar sizes, leave the stated headspace, remove bubbles as directed, clean the rim, and apply the lid according to the lid manufacturer’s current instructions. Process the filled jars with the exact canner method and schedule for that formula. Adjust for elevation using the table attached to the same procedure. Begin timing only at the point the procedure specifies, maintain the required condition for the full time, and follow its instructions for interruptions or pressure loss.

Do not shorten a process, enlarge the jar, thicken the sauce, or increase low-acid ingredients. Do not infer that a pressure-canner option cancels an acidification step; follow whatever the chosen tested procedure states. If the canner stops meeting the required boil, pressure, or heat condition, use the tested authority’s restart guidance rather than estimating how much time remains.

After processing, remove or cool jars exactly as directed and keep them undisturbed for the specified period. Do not force-cool a pressure canner or tighten lids after processing. If a required step was missed or the process was interrupted and no tested recovery direction applies, treat the batch as not safely canned; do not rely on smell, appearance, or a later boil to validate an unverified process.

When the tested cooling period is complete, check each seal by the method the source provides. Label sealed jars with the product and processing date, remove screw bands if the procedure recommends it, and store jars in a clean, cool, dark place. Avoid heat, freezing, moisture, and direct sunlight. A jar that did not seal is not shelf-stable; follow the tested authority’s timely reprocessing or refrigeration direction instead of placing it in the pantry.

Inspect every jar before opening. CDC advises discarding home-canned food when the container is leaking, bulging, swollen, damaged, spurts liquid or foam on opening, shows mold or discoloration, or smells bad. Do not taste suspect food. Botulinum toxin cannot be seen, smelled, or tasted, so an apparently normal jar does not validate an untested recipe or a missed processing step.

Open jars carefully and follow current official guidance for the specific food before serving. Refrigerate leftovers promptly. Keep your recipe source, canning date, jar size, canner method, elevation, and any processing notes with the batch so a later safety question can be answered from records rather than memory.

If you discover that an ingredient ratio, acidification amount, jar size, headspace, pressure, elevation adjustment, or processing time differed from the tested directions, do not serve the product based on a seal check alone. Contact Cooperative Extension or the source authority for disposal guidance. When a jar’s safety is uncertain, protect people and animals from exposure while discarding it according to CDC instructions. Keep suspect jars separate from food that will be served.