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University of Illinois Extension

Unsafe & Outdated Canning Methods

  • Open-kettle method; no processing in a boiling water bath canner or pressure canner is done, and thus is unsafe
  • Sealing jams, jellies, preserves, and butters with wax or paraffin; often allows harmful mold growth. Print a Fact Sheet on mold.
  • Do not use recipes from celebrity chefs and unreliable internet sources; they often use unsafe, outdated, non-research based methods
  • Do not invert hot jars of jam, jelly, etc.
  • Steam canning; inadequate research for processing times
  • Do not use microwave oven, electric oven, slow cookers, convection oven, dishwasher, sun canning, or other methods besides a boiling water bath canner or pressure canner. These methods can be extremely dangerous and are NOT allowed for processing. The only safe and approved method is using a boiling water bath canner or pressure canner. However, if a pressure canner is used in a cottage food operation, it must only be for properly acidified and permitted foods, NOT for low-acid foods. (See Boiling Water Bath Canning versus Pressure Canning)