NDSU Extension - Mercer County


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Home Canning

home canning, botulism, pressure canning, canning low-acid foods, food preservation

Submitted by Dena Kemmet, Extension Agent/Family and Consumer Sciences

All home-canned foods should be canned according to tested recipes and procedures from USDA. Low-acid and tomato foods not canned according to these recommendations or other USDA-endorsed recommendations present a risk of botulism.

If it is possible that any deviation from the USDA-endorsed methods occurred, to prevent the risk of botulism, low-acid and tomato foods should be boiled in a saucepan before consuming even if you detect no signs of spoilage. At altitudes below 1,000 ft, boil foods for 10 minutes. Add an additional minute of boiling time for each additional 1,000 ft elevation.

Make sure your food preservation information is always current with up-to-date tested guidelines.

Pressure canning is the only recommended method for canning meat, poultry, seafood, and vegetables.

The bacterium Clostridium botulinum is destroyed in low-acid foods when they are processed at the correct time and pressure in pressure canners. Using boiling water canners for these foods poses a real risk of botulism poisoning.

If Clostridium botulinum bacteria survive and grow inside a sealed jar of food, they can produce a poisonous toxin. Even a taste of food containing this toxin can be fatal. Boiling food 10 minutes at altitudes below 1,000 ft should destroy this poison when it is present. For altitudes at and above 1,000 ft, add 1 additional minute per 1,000 ft additional elevation. Caution: To prevent the risk of botulism, low-acid and tomato foods not canned according to the recommendations in this publication or according to other USDA-endorsed recommendations should be boiled as above, in a saucepan before consuming, even if you detect no signs of spoilage. This is not intended to serve as a recommendation for consuming foods known to be significantly under processed according to current standards and recommended methods. It is not a guarantee that all possible defects and hazards with other methods can be overcome by this boiling process.

All low-acid foods canned according to the approved recommendations may be eaten without boiling them when you are sure of all the following:

  1. Food was processed in a pressure canner.
  2. Gauge of the pressure canner was accurate.
  3. Up-to-date researched process times and pressures were used for the size of jar, style of pack, and kind of food being canned.
  4. The process time and pressure recommended for sterilizing the food at your altitude was followed.
  5. Jar lid is firmly sealed and concave.
  6. Nothing has leaked from jar.
  7. No liquid spurts out when jar is opened.
  8. No unnatural or “off” odors can be detected.

It is important to know your approximate elevation or altitude above sea level in order to determine a safe processing time for canned foods

Have you gotten your pressure canner gauge checked yet? Dial gauges need to be checked once a year to be sure they are accurate; otherwise you risk foodborne illness from undercooked food. For more information, see “Questions and Answers About Using a Pressure Canner” at www.ag.ndsu.edu/pubs/preservation.html

Source: Julie Garden-Robinson, NDSU Professor and Food and Nutrition Specialist

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