Heidi Strawn
February 18, 2009

One of the best places to go for the latest canning and food preservation information–and to ensure food safety in your kitchen: your cooperative extension agent.

You can also read detailed articles on Canning Fruits and Vegetables by Sue Weaver and Preserving Fruits and Vegetables (including a recipe!) by Cheryl Morrison.

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Common Canning Problems
Here’s a list of common canning problems compiled by the Clemson University Extension.

  • Loss of liquid from glass jars during processing
    This is not a sign of spoilage; do not open to replace liquid. However, if at least half of the liquid is lost, refrigerate the jars and use within two to three days.
  • Imperfect seal
    Discard food unless the trouble was detected within a few hours.  Canned food can safely be recanned if the unsealed jar is discovered within 24 hours.  To re-can, remove the lid and check the jar sealing surface for tiny nicks.  Change the jar if necessary; add a new treated lid and reprocess using the same processing time.
  • Product dark at top of jar
    Not necessarily a sign of spoilage.
  • Cloudy liquid
    Sometimes denotes spoilage.
  • Color changes that are undesirable
  • Sediment in jars
    Not necessarily a sign of spoilage.
  • Spoilage

  • Floating (especially some fruits)

For more on these problems, check out this page from the Clemson University Cooperative Extension Service.

Source: Extension Food Safety Specialist, Clemson University

Do You Commit Canning Sins?
Utah State University Extension has a list of “Major Canning Sins,” including the following:
  • Learn to avoid canning problems for food safetyMaking up own canning recipe.
  • Adding extra starch, flour or other thickener to recipe.
  • Adding extra onions, chili, bell peppers, or other vegetables to salsas.
  • Using oven instead of water bath for processing.
  • Not making altitude adjustments.
  • Not venting pressure cooker first.
  • Not having gauge pressure canners tested annually.
  • Failure to acidify canned tomatoes.
  • Cooling pressure canner under running water.
  • Letting food cool before processing in the recipes that call for “hot pack.”

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