Heirloom tomatoes are prized for their rich, complex flavors and vibrant colors, making them perfect for canning. Canning heirloom tomatoes locks in their freshness and lets you enjoy the taste of summer all year round. This guide will walk you through a reliable recipe and tips for safely preserving these delicious tomatoes.
Ingredients
- 10 pounds ripe heirloom tomatoes (mixed varieties recommended)
- 2 teaspoons kosher salt (optional, for flavor)
- 1/4 cup bottled lemon juice (to ensure acidity)
- Water (for blanching and filling jars)
- Equipment: quart-sized canning jars, lids, and rings
Instructions
- Prepare your canning supplies: Wash jars, lids, and rings in hot, soapy water. Sterilize jars by boiling them in water or running through a hot dishwasher cycle. Keep lids warm but do not boil.
- Wash and blanch the tomatoes: Rinse tomatoes thoroughly. Bring a large pot of water to a boil. Prepare an ice bath in a large bowl. Working in batches, submerge tomatoes in boiling water for 30-60 seconds until skins begin to loosen, then transfer immediately to ice bath.
- Peel and core the tomatoes: Once cool, remove skins by gently pulling them off. Core out the tough stem ends and any blemishes.
- Crush or quarter tomatoes: Depending on preference, either crush tomatoes by hand or cut into quarters. Avoid pureeing unless making a sauce.
- Add lemon juice and salt to jars: Pour 1 tablespoon bottled lemon juice into each pint jar or 2 tablespoons into quart jars to ensure safe acidity. Add 1/2 teaspoon salt per pint or 1 teaspoon per quart if desired.
- Pack tomatoes into jars: Fill jars with prepared tomatoes, leaving about 1/2-inch headspace at the top. Do not overfill.
- Remove air bubbles: Run a non-metallic spatula or chopstick around the inside of the jars to release trapped air bubbles.
- Wipe rims and apply lids: Wipe jar rims clean with a damp cloth to ensure a good seal. Place lids on jars and screw on rings until fingertip tight.
- Process jars in boiling water bath: Place jars in a canner or large pot with a rack. Cover jars by at least 1-2 inches of water. Bring water to a rolling boil and process pint jars for 40 minutes, quart jars for 45 minutes (adjust time for altitude).
- Cool and store: Remove jars carefully and place on a towel or rack to cool undisturbed for 12-24 hours. Check seals; lids should not flex up and down when pressed. Store sealed jars in a cool, dark place.
Tips
- Use bottled lemon juice: Fresh lemon juice varies in acidity, so bottled is recommended to ensure safe pH levels for canning.
- Choose firm, ripe tomatoes: Overripe tomatoes can yield thinner, watery canned tomatoes. Select tomatoes that are ripe but still firm for best texture.
- Adjust processing times for altitude: If you live above 1,000 feet elevation, increase processing time by 5-10 minutes or follow your local extension service guidelines.
- Don’t skip the blanching step: Peeling tomatoes is easier after blanching, but it also helps reduce bacteria on the skin surface.
Serving Suggestions
Canned heirloom tomatoes are incredibly versatile. Use them as a base for homemade pasta sauces, hearty stews, chili, or soups. They can also be blended into salsas or simmered down to make rich tomato gravy. Simply heating them with garlic and fresh herbs makes a quick, flavorful side or topping for grilled meats and vegetables.
Variations
Try adding fresh basil leaves or a clove of crushed garlic into each jar before sealing to infuse additional flavor during storage. For a smoky twist, roast the tomatoes before canning. Another variation is to make a chunky tomato sauce by simmering the peeled tomatoes with onions, bell peppers, and your favorite spices before canning in sterilized jars.
Storage and Reheating
Properly canned heirloom tomatoes will last up to 12-18 months when stored in a cool, dark cupboard away from heat sources. After opening, refrigerate leftovers and use within 5-7 days. Reheat gently on the stove or microwave until warmed through; avoid boiling to preserve texture and flavor. If you notice any off smells, discoloration, or mold, discard immediately.
Frequently Asked Questions
Can I use any type of heirloom tomato for canning?
Yes, most heirloom varieties can be canned, but firmer tomatoes like Brandywine, Cherokee Purple, or Green Zebra work best for maintaining texture. Very soft or watery tomatoes may result in a thinner canned product.
Why do I need to add lemon juice or acid to canned tomatoes?
Tomatoes are borderline acidic and adding bottled lemon juice or citric acid ensures the pH is low enough to prevent the growth of harmful bacteria like botulism during storage.
Is it safe to can heirloom tomatoes without peeling them?
It’s not recommended. The skin can harbor bacteria and may affect the texture and quality. Peeling after blanching is a simple step to improve safety and taste.
Can I freeze canned tomatoes instead of storing them on the shelf?
Yes, freezing is an alternative to canning and preserves flavor well, but canned tomatoes take up less space and don’t require thawing before use. However, freezing requires freezer space and the texture may change slightly upon thawing.
What if my jars didn’t seal properly?
If a jar doesn’t seal, refrigerate and use the contents within a week. You can also reprocess the jar with a new lid and the full processing time to attempt resealing.
Can I add herbs or other vegetables to the tomatoes before canning?
Yes, but be cautious. Some herbs and vegetables may alter the acidity or require different processing times. For safety, add only tested recipes or small amounts of herbs like basil or oregano. Avoid adding low-acid vegetables like onions or peppers unless following a tested recipe.
Preserving heirloom tomatoes through canning is a rewarding way to enjoy their unique flavors year-round. With proper technique and attention to safety, your jars will be a delicious reminder of summer’s bounty.
For an extra tip: consider labeling your jars with the date and variety to keep track of your preserved harvest and enjoy the best quality over time.
Remember, canning is both an art and a science, so always follow trusted guidelines and adjust for your local conditions to ensure safe, tasty results.
Choosing the Right Canning Method
When it comes to canning heirloom tomatoes, selecting the appropriate method is crucial to ensure safety and preserve the best flavor and texture. The two primary techniques are water bath canning and pressure canning. Because tomatoes are naturally acidic but sometimes borderline in acidity, the addition of lemon juice or citric acid allows for safe water bath canning, which is easier and more accessible for most home canners.
Water bath canning involves submerging jars in boiling water for a specified time, usually between 35 to 45 minutes depending on altitude and jar size. This method is ideal for whole, crushed, or juiced tomatoes with added acid. Pressure canning, on the other hand, uses high-pressure steam to reach temperatures above boiling, effectively killing more heat-resistant bacteria and spores. This method is preferred when canning tomato products combined with low-acid ingredients, such as vegetables or meats.
For pure heirloom tomatoes, water bath canning is generally sufficient and retains the delicate flavors well. However, if your recipe includes ingredients like onions, peppers, or beans, pressure canning is the safest option. Always consult trusted canning guidelines to match your recipe to the correct method.
Preparing Heirloom Tomatoes for Canning
Proper preparation of heirloom tomatoes is key to achieving the best results in your canning endeavors. Begin by selecting ripe but firm tomatoes to avoid mushy textures in your final product. Wash the tomatoes thoroughly under running water to remove dirt and any pesticide residues.
Next, blanch the tomatoes by plunging them into boiling water for 30-60 seconds until skins start to crack, then immediately transfer to an ice bath. This process loosens the skin, making peeling easier and ensuring better texture. Remove skins carefully, then core the tomatoes if desired.
Depending on your recipe, you may leave the tomatoes whole, crush them by hand or with a spoon, or blend them for a smoother sauce. If you prefer, you can remove some of the seeds, although many find that leaving them in adds to the rustic flavor and appearance. Remember that larger tomatoes may require halving or quartering to fit into jars easily.
Enhancing Flavors with Herbs and Spices
While heirloom tomatoes boast complex and varied flavors on their own, adding herbs and spices can elevate your canned creations to new heights. Classic pairings include fresh basil, oregano, thyme, and bay leaves, which complement the natural sweetness and acidity of the tomatoes.
When adding herbs, consider using fresh leaves or dried spices depending on availability. Fresh herbs generally provide a brighter, more vibrant flavor, while dried herbs are more concentrated and can be added in smaller quantities. For safety, add herbs sparingly and avoid exceeding tested amounts, as excessive additions can impact acidity and preservation.
Other flavorful additions include minced garlic, cracked black pepper, or a pinch of red pepper flakes for heat. However, be cautious with vegetables like onions or peppers, as these are low-acid and may require pressure canning if added in significant quantities. To maintain safety, it’s best to add these only in small amounts or follow a trusted tested recipe.
Using Heirloom Tomatoes in Different Canned Products
Heirloom tomatoes can be preserved not only as whole or crushed tomatoes but also as part of a variety of delicious canned products, each capturing summer’s bounty in different ways:
- Tomato Juice: Strain crushed heirloom tomatoes through a fine sieve or cheesecloth to extract fresh juice. Add lemon juice or citric acid for acidity, then process as usual.
- Salsa: Combine peeled, diced heirloom tomatoes with onions, peppers, cilantro, and lime juice for a zesty canned salsa. Use pressure canning to ensure safety due to the inclusion of low-acid vegetables.
- Tomato Sauce and Purees: Simmer peeled tomatoes with garlic, herbs, and olive oil until thickened, then can for a ready-made sauce perfect for pasta or pizza.
- Sun-Dried Tomato Paste: Slow roast or dehydrate tomatoes before pureeing into a concentrated paste that can be canned or frozen for later use in stews and spreads.
Each of these products highlights the unique flavor profiles of heirloom tomatoes, allowing you to enjoy their rich colors and tastes throughout the year.
High-Altitude Adjustments for Canning
Altitude affects boiling temperature, which in turn influences the effectiveness of heat processing during canning. If you live at higher elevations—typically above 1,000 feet—adjustments must be made to processing times or pressures to ensure food safety.
For water bath canning, increase the processing time by 5 to 15 minutes depending on your elevation. For example, if your base recipe calls for 40 minutes at sea level, you might need to process for 45-55 minutes at 3,000 feet. For pressure canning, raise the pressure setting accordingly (usually by 5 pounds per 1,000 feet elevation).
Consult your local extension office or trusted canning resources to determine the exact adjustments required. These modifications are crucial to prevent spoilage and botulism risks, especially when canning low-acid or mixed ingredients alongside your heirloom tomatoes.
Common Mistakes to Avoid When Canning Heirloom Tomatoes
Even experienced home canners can fall prey to common pitfalls that affect the quality and safety of canned heirloom tomatoes. Being aware of these errors can save you time, effort, and potential health risks:
- Skipping the Acid Addition: Failing to add bottled lemon juice or citric acid can allow harmful bacteria to grow.
- Using Damaged or Overripe Tomatoes: Soft or bruised fruit can lead to poor texture and spoilage.
- Improper Jar Sterilization: Not sterilizing jars and lids correctly increases contamination risk.
- Underprocessing: Cutting processing times short to save time compromises food safety.
- Ignoring Altitude Adjustments: Processing at sea level times in high-altitude areas can lead to underprocessing.
- Not Checking Seals: Reusing lids or failing to confirm a proper vacuum seal can cause spoilage.
By following tested recipes carefully, paying attention to detail, and adhering to safety guidelines, you can avoid these mistakes and enjoy delicious, shelf-stable heirloom tomato preserves.
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