How to Can Soup: A Comprehensive Guide
Canning soup allows you to preserve your delicious homemade recipes for later enjoyment, providing a convenient and shelf-stable meal that is ready whenever you need it. However, successful and safe canning requires strict adherence to tested recipes and processes, ensuring the elimination of harmful bacteria.
Why Can Soup? Understanding the Benefits and Risks
Canning soup at home offers numerous advantages, but it’s crucial to understand the underlying science to ensure food safety. Properly canned soup can last for over a year on the pantry shelf, providing a cost-effective way to enjoy seasonal ingredients year-round.
- Preservation of Freshness: Canning allows you to capture the peak flavors of your garden produce or locally sourced ingredients.
- Convenience and Time Savings: Having pre-made soup on hand simplifies meal preparation, especially during busy weeknights.
- Control Over Ingredients: You can avoid artificial additives, preservatives, and excessive sodium found in commercially canned soups.
- Reduced Food Waste: Canning helps preserve leftover ingredients and prevent food waste.
However, improper canning can lead to the growth of Clostridium botulinum, which produces a deadly toxin that causes botulism. Low-acid foods, like many soups, require pressure canning to reach temperatures high enough to kill these bacteria. Water bath canning is not safe for most soup recipes.
The Essential Equipment for Canning Soup
Before you begin, gather all the necessary equipment. Proper equipment ensures a safe and efficient canning process.
- Pressure Canner: A must-have for processing low-acid foods like most soups. Ensure it’s in good working order and the pressure gauge is accurate.
- Canning Jars: Use jars specifically designed for canning (e.g., Ball or Kerr). Inspect for chips or cracks. Use the appropriate size for your recipe.
- Lids and Bands: New lids are required for each batch to ensure a proper seal. Reusable bands can be used repeatedly.
- Canning Utensils: A jar lifter, wide-mouth funnel, bubble remover, and magnetic lid lifter make the process easier and safer.
- Large Stockpot: For preparing the soup.
- Clean Towels: To protect surfaces and handle hot jars.
Choosing a Tested and Approved Soup Recipe
Never improvise when canning soup. Always use a recipe from a reputable source that has been tested for safety.
- USDA Complete Guide to Home Canning: The gold standard for home canning information.
- National Center for Home Food Preservation (NCHFP): Offers a wealth of research-based recipes and resources.
- Ball Blue Book Guide to Preserving: A popular and trusted resource for home canners.
Look for recipes that specify the precise ingredients, processing times, and pressure settings. Avoid recipes that call for adding thickeners (flour, cornstarch, rice, pasta) before canning. These can interfere with heat penetration and compromise safety. You can always add thickeners after opening the jar and reheating the soup.
The Step-by-Step Canning Process
Carefully follow these steps to ensure a safe and successful canning experience.
- Prepare Jars and Lids: Wash jars in hot, soapy water and rinse thoroughly. Sanitize the jars by simmering them in hot water for 10 minutes. Keep jars hot until ready to fill. Heat lids in hot water (but do not boil) to soften the sealing compound.
- Prepare the Soup: Follow your chosen recipe precisely. Do not deviate from the ingredients or quantities.
- Fill the Jars: Using a wide-mouth funnel, ladle the hot soup into the hot jars, leaving the headspace specified in the recipe (usually 1 inch).
- Remove Air Bubbles: Use a bubble remover (or a clean spatula) to gently release any trapped air bubbles.
- Wipe Jar Rims: Use a clean, damp cloth to wipe the jar rims to ensure a clean sealing surface.
- Place Lids and Bands: Center a lid on each jar, then screw on a band finger-tight (not too tight).
- Load the Canner: Place the jars in the pressure canner, following the manufacturer’s instructions. Add the required amount of water.
- Process the Soup: Secure the canner lid and bring the canner up to the specified pressure. Process for the time indicated in the recipe.
- Cool and Depressurize: Allow the canner to cool naturally until the pressure returns to zero. Carefully remove the lid and let the jars sit for 5 minutes.
- Check the Seals: After 12-24 hours, check the seals by pressing down on the center of each lid. If the lid flexes, it is not sealed. Reprocess the unsealed jars within 24 hours or refrigerate and use immediately.
- Store the Canned Soup: Remove the bands (you can reuse them). Label the jars with the date and contents. Store in a cool, dark, and dry place.
Common Mistakes to Avoid
Avoid these common errors to prevent spoilage and ensure safety.
- Using Unapproved Recipes: This is the most dangerous mistake. Only use tested and approved recipes from reputable sources.
- Incorrect Headspace: Improper headspace can affect sealing.
- Insufficient Processing Time or Pressure: This can lead to botulism.
- Adding Thickeners Before Canning: Thickeners interfere with heat penetration.
- Failure to Vent the Canner: Venting removes air from the canner, ensuring proper pressure.
- Improper Cooling: Rapid cooling can weaken seals.
Troubleshooting Common Canning Problems
Even with careful preparation, problems can occasionally arise. Here are solutions to some common canning issues.
| Problem | Possible Cause | Solution |
|---|---|---|
| Jars Not Sealing | Damaged jar rims, improper headspace, loose bands | Use new lids, ensure proper headspace, tighten bands properly (finger-tight), reprocess |
| Siphoning (Liquid Loss) | Rapid pressure changes, overfilling jars | Avoid rapid pressure changes, ensure proper headspace, use correct processing time |
| Cloudy Broth | Minerals in water, starch in vegetables | Use filtered water, blanch vegetables properly, add a tablespoon of lemon juice per jar |
Frequently Asked Questions (FAQs) About Canning Soup
Can I use my grandmother’s soup recipe?
No, unless it has been tested and approved for safe canning by a reliable source like the USDA or NCHFP. Old recipes often lack crucial information regarding processing times and safe ingredients. It is best to find a similar tested recipe.
Can I can soup with dairy or cream?
Dairy products are not recommended for home canning. The high fat content can interfere with heat penetration and create a breeding ground for bacteria. Freeze dairy-based soups instead.
Can I can soup with pasta or rice?
It’s generally not recommended to can soup with pasta or rice already added. They can become mushy and absorb too much liquid, potentially affecting the soup’s consistency and safety. Add cooked pasta or rice when you reheat the soup. Some approved recipes call for very small quantities of specifically approved pasta shapes but only in those recipes.
What vegetables are safe to can in soup?
Most vegetables are safe to can in soup, but be sure to follow the recipe’s guidelines. Some vegetables, like potatoes, require specific preparation methods. Low-acid vegetables such as beans and corn are safe, but must be pressure canned.
What is the proper headspace for canning soup?
Generally, a 1-inch headspace is recommended for canning soup. Always refer to the recipe for specific instructions. Incorrect headspace can cause sealing failures.
How do I know if my pressure canner is working properly?
Check the pressure gauge for accuracy before each use. Have it tested annually by your local extension office. Also, ensure the vent pipe is clear. If you have a weighted gauge canner it should rock gently during the processing time.
How long does canned soup last?
Properly canned soup can last for at least a year, and possibly longer. However, for best quality, it is recommended to use it within a year. Always check for signs of spoilage before consumption.
What are the signs of spoilage in canned soup?
Bulging lids, leaking jars, and an off-odor are all signs of spoilage. Do not consume any soup from jars showing these signs. If any doubt exists about the safe preservation of your soup discard it safely.
Can I can soup in quart jars?
Yes, but you must adjust the processing time according to the recipe. Pint jars generally require shorter processing times than quart jars. Always use the processing time specified for the jar size.
What if I don’t have a pressure canner?
For most soups, a pressure canner is essential. Water bath canning is not safe for low-acid foods like most soups. High-acid soups (containing mostly tomatoes with an added acid like lemon juice or vinegar), may be water bath canned if a tested recipe explicitly provides this option.
Can I reprocess jars that didn’t seal?
Yes, you can reprocess unsealed jars within 24 hours. Use new lids and follow the original processing instructions. If the jar still doesn’t seal, refrigerate the soup and use it immediately.
Where can I find more information on safe canning practices?
Consult the USDA Complete Guide to Home Canning, the National Center for Home Food Preservation (NCHFP), or your local extension office for reliable information and resources.