Home canner’s column: Enjoy nature’s bounty all year
by By Kaye M. Smith Extension Agent, Family & Consumer Sciences
Jul 06, 2011 | 1736 views | 0 0 comments | 11 11 recommendations | email to a friend | print
More canning tips

Would you like to enjoy nature’s bounty from the summer garden all year long?

If you are planning to preserve foods at home this summer, there are a few questions you might have about the safety of home canned foods.

Q. Can jars of food spoil after being sealed for several weeks or months?

A. If you follow the instructions given in Extension and USDA tested recipes for processing canned foods and they seal correctly, they should not spoil. The processing times provided in these recipes should be long enough to kill disease-causing and spoilage microorganisms. It is important to store your canned foods in a cool, dry place. The ideal temperature is 50 to 70 degrees. High temperatures cause canned food to lose quality. Low temperatures may cause your food to freeze, which can crack your jars or break the seals. If your storage area becomes too cold, wrap your jars in paper or cover them with a blanket.

Q. How do I know if my canned food has spoiled?

A. If bacteria and yeast are growing, they can produce gas that causes seals to break or lids to bulge. Before you open a jar, examine the seal carefully. It should be tight and the center should be concave. Hold the jar at eye level, turn it and examine the outside for streaks of food coming from the top. Look for rising air bubbles and unusual color. Open the jar and look for mold under the lid and on top of the food. It may be blue, black, white or green. If you open a jar that has not sealed properly or see possible signs of spoilage, NEVER TASTE THE FOOD. Dispose of spoiled and suspect foods properly. Boil vegetables, meats and other low-acid foods, including tomatoes, in the jars immersed in water for 30 minutes, if the seals are broken. Throw the jars of food in the trash after they have cooled. If the jars are still sealed, throw them in the trash. Be sure to wash your hands well.

Q. Is it safe to process food in the microwave or conventional oven?

A. No, safe processing times have not been established.

Q. My grandmother canned in a big kettle. Is this safe?

A. The open kettle method, or cooking food in a large pan and packing it in hot jars without processing, is not a safe way to can. Dangerous bacteria and spoilage organisms may not be destroyed.

Q. If a lid does not seal, can the food be processed?

A. Yes, if done within 24 hours. Remove contents of jar and proceed as if food were fresh. Check jar rim for nicks or cracks; use new lid. Use same processing time.

Q. Should I sterilize jars before canning?

A. It is not necessary to sterilize jars if they will be processed in a water-bath canner for 10 minutes or in a pressure canner. If they will not be processed for at least 10 minutes, boil them in water for 10 minutes before filling with food.

If you have questions you’d like addressed in the “Home Canner’s Column,” call your local University of Tennessee Extension office at 728-7001. The Bradley County Cannery is now open by appointment to assist with your canning needs. Call Retha Odom for an appointment and more information at 728-7031.